Factors Predicting Early Major Adverse Events in the Intensive Care Unit After Successful Cardiac Surgery for Congenital Heart Disease in Full-Term Neonates

OBJECTIVE

In this study, we aimed to evaluate the factors affecting major adverse event (MAE) development after full-term neonatal cardiac surgery.

METHODS

This study was conducted retrospectively on newborns who underwent congenital heart surgery between June 1, 2020, and June 1, 2022. MAE was defined as the presence of at least one of the following: cardiac arrest, unplanned reoperation, emergency chest opening, admission to the advanced life support system, and death. The role of blood lactate level, vasoactive inotropic score (VIS), and cerebral near-infrared spectroscopy (NIRS) changes in predicting MAE was investigated.

RESULTS

A total of 240 patients (50% male) were operated during the study period. The median age of patients was seven days (interquartile range 3-10 days). MAE was detected in 19.5% of the cases. Peak blood lactate levels >7 mmol/liter (area under the curve [AUC] 0.72, 95% confidence interval [CI] [0.62-0.82], P<0.001, sensitivity 76%, specificity 82%, positive predictive value [PPV] 88%) was an independent risk factor for MAE (odds ratio [OR] 2.7 [95% CI 1.3-6]). More than 30% change in NIRS value during the operative period (AUC 0.84, 95% CI [0.80-0.88], P<0.001, sensitivity 65%, specificity 85%, PPV 90%) was a strong predictor of MAE. VIS > 10 was an independent risk factor (AUC 0.75, 95% CI [0.70-0.84], P<0.001, sensitivity 86%, specificity 80%, PPV 84%) and strongly predicted MAE (OR 1.4 [95% CI 0.9-5]).

CONCLUSION

Cerebral NIRS changes > 30%, high blood lactate levels, and VIS score within the 48 hours may help to predict the development of MAE in the postoperative period.

Validation of Blood Transfusion Risk Scores (TRACK and TRUST) in a Cardiac Surgery Service in Brazil

INTRODUCTION

Transfusion of red blood cells is recurrent in cardiac surgery despite the well-established deleterious effects. Identifying patients with higher chances of requiring blood transfusion is essential to apply strategic preventive measures to reduce such chances, considering the restricted availability of this product. The most used risk scores to predict blood transfusion are the Transfusion Risk and Clinical Knowledge (TRACK) and Transfusion Risk Understanding Scoring Tool (TRUST). However, these scores were not validated for the Brazilian population. The objective of this study was to assess the accuracy of TRACK and TRUST scores in estimating the need for postoperative transfusion of red blood cell concentrates (TRBCC) after cardiac surgery.

METHODS

A clinical retrospective study was conducted using the database of a Brazilian reference service composed of patients operated between November 2019 and September 2021. Scores were compared using Mann-Whitney U test. Hosmer-Lemeshow goodness of fit test assessed calibration of the scores. Accuracy was assessed using the area under the receiver operating characteristic curve (AUC). All analyses considered a level of significance of 5%. The study was approved by the research ethics committee (CAAE 55577421.4.0000.5201).

RESULTS

This study assessed 498 patients. Only the TRACK score presented good calibration (P=0.238; TRUST P=0.034). AUC of TRACK was 0.678 (95% confidence interval 0.63 to 0.73; P<0.001), showing a significant accuracy.

CONCLUSION

Between the scores analyzed, only the TRACK score showed a good calibration, but low accuracy, to predict postoperative TRBCC after cardiac surgery.

The diamond ratio: A visual indicator of the extent of heterogeneity in meta-analysis

The result of a meta-analysis is conventionally pictured in the forest plot as a diamond, whose length is the 95% confidence interval (CI) for the summary measure of interest. The Diamond Ratio (DR) is the ratio of the length of the diamond given by a random effects meta-analysis to that given by a fixed effect meta-analysis. The DR is a simple visual indicator of the amount of change caused by moving from a fixed-effect to a random-effects meta-analysis. Increasing values of DR greater than 1.0 indicate increasing heterogeneity relative to the effect variances. We investigate the properties of the DR, and its relationship to four conventional but more complex measures of heterogeneity. We propose for the first time a CI on the DR, and show that it performs well in terms of coverage. We provide example code to calculate the DR and its CI, and to show these in a forest plot. We conclude that the DR is a useful indicator that can assist students and researchers to understand heterogeneity, and to appreciate its extent in particular cases.

Total Arterial Coronary Bypass Graft Surgery is Associated with Better Long-Term Survival in Patients with Multivessel Coronary Artery Disease: a Systematic Review with Meta-Analysis

INTRODUCTION

The benefit of total arterial revascularization (TAR) in coronary artery bypass grafting (CABG) remains a controversial issue. This study sought to evaluate whether there is any difference on the long-term results of TAR and non-TAR CABG patients.

METHODS

The Medical Literature Analysis and Retrieval System Online (MEDLINE), Excerpta Medica dataBASE (EMBASE), Cochrane Central Register of Controlled Trials (CENTRAL/CCTR), Clinical Trials.gov, Scientific Electronic Library Online (SciELO), Literatura Latino-Americana e do Caribe em Ciências da Saúde (LILACS), and Google Scholar databases were searched for studies published by October 2020. Randomized clinical trials and observational studies with propensity score matching comparing TAR versus non-TAR CABG were included. Random-effects meta-analysis was performed. The current barriers to implementation of TAR in clinical practice and measures that can be used to optimize outcomes were reviewed.

RESULTS

Fourteen publications (from 2012 to 2020) involving a total of 22,746 patients (TAR: 8,941 patients; non-TAR: 13,805 patients) were included. The pooled hazard ratio (HR) for long-term mortality (over 10 years) was lower in the TAR group than in the non-TAR group (random effect model: HR 0.676, 95% confidence interval 0.586-0.779, P<0.001). There was evidence of low heterogeneity of treatment effect among the studies for mortality, and none of the studies had a particular impact on the summary result. The result was not influenced by age, sex, or comorbidities. We identified low risk of publication bias related to this outcome.

CONCLUSION

This review found that TAR presents the best long-term results in patients who undergo CABG. Given that many patients are likely to benefit from TAR, its use should be encouraged.

Frailty Significantly Associated with a Risk for Mid-term Outcomes in Elderly Chronic Coronary Syndrome Patients: a Prospective Study

INTRODUCTION

Frailty is a condition of elderly characterized by increased vulnerability to stressful events. Frail patients are more likely to have adverse events. The purposes of this study were to define frailty in patients aged ≥ 70 years with chronic coronary syndrome (CCS) and to evaluate mortality and prognostic significance of frailty in these patients.

METHODS

We included 99 patients, ≥ 70 years old (mean age 74±5.3 years), with diagnosis of CCS. They were followed-up for up to 12 months. The frailty score was evaluated according to the Canadian Study of Health and Aging (CSHA). All patients were divided as frail or non-frail. The groups were compared for their characteristics and clinical outcomes.

RESULTS

Fifty patients were classified as frail, and 49 patients as non-frail. The 12-month Major Adverse Cardiac Events (MACE) rate was 69.4% in frail patients and 20% in non-frail patients. Frailty increases the risk for MACE as much as 3.48 times. Two patients died in the non-frail group and 11 patients died in the frail group. Frailty increases the risk for death as much as 6.05 times. When we compared the aforementioned risk factors by multivariate analysis, higher CSHA frailty score was associated with increased MACE and death (relative risk [RR] = 22.94, 95% confidence interval [CI] 3.33-158.19, P=0.001, for MACE; RR = 7.41, 95% CI 1.44-38.03, P=0.016, for death).

CONCLUSION

Being a frail elderly CCS patient is associated with worse outcomes. Therefore, frailty score should be evaluated for elderly CCS patients as a prognostic marker.

Mid-Term Outcome after Tricuspid Valve Replacement

Objective

To evaluate the mid-term survival rate after tricuspid valve replacement (TVR).

Methods

We retrospectively studied 110 consecutive patients who underwent TVR from January 2007 to November 2017. A survival analysis was performed with the Kaplan-Meier method and the log-rank test.

Results

The median survival was 65.81 months. Mean age was 50 (range 39 to 59) years. Forty-eight patients (43.6%) were male, and 62 patients (56.4%) were female. Most of the patients (78.5%) were categorized into the New York Heart Association (NYHA) functional classes III/IV. Seventy-two patients (65.5%) had isolated TVR. Six-three patients (57.3%) had previously undergone heart surgery. The Kaplan-Meier survival rates at one year, three years, and five years were 59.0%±5%, 52.0%±6%, and 48.0%±6%, respectively. A Cox regression analysis demonstrated that the risk factors for mid-term mortality were advanced NYHA class (hazard ratio [HR] 2.430, 95% confidence interval [CI] 1.099-5.375, P=0.028), need for continuous renal replacement therapy (CRRT) treatment (HR 3.121, 95% CI 1.610-6.050, P=0.001), and need for intra-aortic balloon pump (IABP) treatment (HR 3.356, 95% CI 1.072-10.504, P=0.038).

Conclusion

In TVR, impaired cardiac function before the operation and a need for CRRT or IABP treatment after the operation is independently associated with increased mid-term mortality.

Cardiac Shock Wave Therapy for Coronary Heart Disease: an Updated Meta-analysis

Introduction

The aim of this article is to study the efficacy and safety of cardiac shock wave therapy (CSWT) in the treatment of coronary heart disease (CAD).

Methods

A comprehensive search of electronic databases and a manual search of conference papers and abstracts were performed until September 30, 2018. The studies using RevMan 5.3 and STATA 14.0 softwares were reviewed, and meta-analyses were performed on 13 indicators, such as a six-min walking distance test (6MWT), New York Heart Association (NYHA) functional class, Seattle Angina Questionnaire (SAQ) score, angina class (Canadian Cardiology Society [CCS]), etc.

Results

A total of 26 articles were included. The total patient population was 855, of which 781 patients were treated with CSWT. Meta-analyses indicated that 6MWT (mean difference [MD] 75.64, 95% confidence interval [CI] 49.03, 102.25, P<0.00001) and NYHA (MD -0.70, 95% CI -0.92) in the CSWT group were comparable to those in the conventional revascularization group (MD -0.70, 95% CI -0.92, -0.49, P<0.00001). SAQ (MD 10.75, 95% CI 6.66, 14.83, P<0.00001), CCS (MD -0.99, 95% CI -1.13, -0.84, P<0.00001), nitrate dosage (MD -1.84, 95% CI -2.77, -1.12, P<0.00001), LVEF (MD 3.77, 95% CI 2.17, 5.37, P<0.00001), and SSS (MD -4.29, 95% CI -5.61, -2.96, P<0.00001), SRS (MD -2.90, 95% CI -4.85, -0.95, P=0.004), and the exercise test (standard mean difference 0.57, 95% CI 0.12, 1.02, P=0.01) all showed significant differences.

Conclusion

CSWT may offer beneficial effects to patients with CAD, but more large-scale clinical studies are needed to further verify its therapeutic effect.

Developments in the Histopathological Classification of ANCA-Associated Glomerulonephritis

BACKGROUND AND OBJECTIVES

The histopathologic classification for ANCA-associated GN distinguishes four classes on the basis of patterns of injury. In the original validation study, these classes were ordered by severity of kidney function loss as follows: focal, crescentic, mixed, and sclerotic. Subsequent validation studies disagreed on outcomes in the crescentic and mixed classes. This study, driven by the original investigators, provides several analyses in order to determine the current position of the histopathologic classification of ANCA-associated GN.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

A validation study was performed with newly collected data from 145 patients from ten centers worldwide, including an analysis of interobserver agreement on the histopathologic evaluation of the kidney biopsies. This study also included a meta-analysis on previous validation studies and a validation of the recently proposed ANCA kidney risk score.

RESULTS

The validation study showed that kidney failure at 10-year follow-up was significantly different between the histopathologic classes (P<0.001). Kidney failure at 10-year follow-up was 14% in the crescentic class versus 20% in the mixed class (P=0.98). In the meta-analysis, no significant difference in kidney failure was also observed when crescentic class was compared with mixed class (relative risk, 1.15; 95% confidence interval, 0.94 to 1.41). When we applied the ANCA kidney risk score to our cohort, kidney survival at 3 years was 100%, 96%, and 77% in the low-, medium-, and high-risk groups, respectively (P<0.001). These survival percentages are higher compared with the percentages in the original study.

CONCLUSIONS

The crescentic and mixed classes seem to have a similar prognosis, also after adjusting for differences in patient populations, treatment, and interobserver agreement. However, at this stage, we are not inclined to merge the crescentic and mixed classes because the reported confidence intervals do not exclude important differences in prognosis and because an important histopathologic distinction would be lost.

Prognostic Value of Coronary Dominance in Patients Undergoing Elective Coronary Artery Bypass Surgery

Objective

To evaluate the clinical impact of coronary dominance type in terms of early and long-term outcomes in patients undergoing elective coronary artery bypass grafting (CABG).

Methods

A total of 844 consecutive patients who underwent elective CABG were divided into two groups based on preoperative angiographic views as left dominant (LD) and right dominant or co-dominant (RD+CD). The measured outcomes were postoperative complications, 30-day mortality, long-term mortality, and major adverse cardiac and cerebrovascular events (MACCE).

Results

RD+CD was present in 87.9% (n=742) and LD in 12.1% (n=102) of patients. Postoperative complications, 30-day mortality, and 30-day readmissions were similar in both groups. The median duration of follow-up was 3.4 years. LD was not an independent predictor of mortality (adjusted hazard ratio [HR] 1.53, 95% confidence interval [CI] 0.89-2.45, P=0.12), but it was an independent predictor of MACCE in the long term (adjusted HR 2.18, 95% CI 1.39-3.42, P=0.001).

Conclusion

In patients undergoing elective surgical revascularization, left coronary dominance is associated with increased MACCE risk in the long term. Therefore, the assessment of coronary dominance type should be an integral part of outpatient management after CABG.

A Post Hoc Analysis of Statin Use in Tolvaptan Autosomal Dominant Polycystic Kidney Disease Pivotal Trials

BACKGROUND AND OBJECTIVES

Tolvaptan is approved to slow kidney function decline in adults with autosomal dominant polycystic kidney disease (ADPKD) at risk of rapid progression. Because in vitro studies indicated that the tolvaptan oxobutyric acid metabolite inhibits organic anion-transporting polypeptide (OATP)1B1 and OATP1B3, United States prescribing information advises avoiding concurrent use with OATP1B1/1B3 substrates, including hepatic hydroxymethyl glutaryl-CoA reductase inhibitors (statins). This post hoc analysis of the pivotal phase 3 tolvaptan trials (Tolvaptan Efficacy and Safety in Management of Autosomal Dominant Polycystic Kidney Disease and Its Outcomes [TEMPO] 3:4 trial [NCT00428948] and Replicating Evidence of Preserved Renal Function: an Investigation of Tolvaptan Safety and Efficacy in ADPKD [REPRISE] trial [NCT02160145]) examined the safety of concurrent tolvaptan/statin use.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

The trials randomized a combined total of 2815 subjects with early- to late-stage ADPKD to tolvaptan (n=1644) or placebo (n=1171) for 3 years (TEMPO 3:4) and 1 year (REPRISE). Statin use was unrestricted, and 597 subjects (21.2% overall; 332 [20.2%] tolvaptan, 265 [22.6%] placebo) received statins. Statin use (duration, dose change, statin change, permanent discontinuation), incidences of statin-related adverse events, and hepatic transaminase elevations were determined for subjects who received tolvaptan+statin, placebo+statin, tolvaptan alone, and placebo alone.

RESULTS

No differences in statin use parameters between tolvaptan- and placebo-treated subjects were observed. No statistically significant increases in commonly reported statin-related adverse events (e.g., musculoskeletal disorders, gastrointestinal symptoms) were seen between subjects receiving tolvaptan+statin and placebo+statin. For example, in TEMPO 3:4, frequencies were 5.4% and 7.8%, respectively, for myalgia (difference -2.4%; 95% confidence interval, -11.2% to 6.4%) and 9.3% and 7.8%, respectively, for abdominal pain (difference 1.5%; -7.9% to 10.9%). In an analysis that excluded participants concurrently using allopurinol, the frequency of alanine transaminase or aspartate transaminase >3× upper limit of normal in the pooled study populations was 3.6% for the tolvaptan+statin group and 2.3% for the placebo+statin group (difference 1.4%; -2.0% to 4.7%).

CONCLUSIONS

Tolvaptan has been used safely in combination with statins in clinical trials.

PODCAST

This article contains a podcast at https://www.asn-online.org/media/podcast/CJASN/2020_04_06_CJN.08170719.mp3.

Is the Newly Defined R2CHA2DS2-Vasc Score a Predictor for Late Mortality in Patients Undergoing Transcatheter Aortic Valve Replacement?

Objective

To assess the performance of the modified R₂CHA₂DS₂-VASc score for predicting mid-to-long-term mortality (> 30 days) in patients undergoing transcatheter aortic valve replacement (TAVR).

Methods

Data of 78 patients who underwent TAVR were retrospectively reviewed. R₂CHA₂DS₂-VASc score was compared with the European System for Cardiac Operative Risk Evaluation II (EuroSCORE II or ES II) and the transcatheter valve therapytranscatheter aortic valve replacement (TVT-TAVR) risk score.

Results

The mean follow-up period was 17.4±9.9 months (maximum 37 months). Early mortality (first 30 days) was observed in 10 (12.8%) patients, whereas mid-to-long-term mortality (> 30 days) was observed in 26 (33.3%) patients. Non-survivors had higher values of R₂CHA₂DS₂-VASc, ES II, and TAVR scores than survivors (P<0.001, P<0.001, and P=0.001, respectively). Analysis of Pearson’s correlation revealed that R₂CHA₂DS₂-VASc score was moderately correlated with ES II and TAVR scores (r=0.51, P<0.001; r=0.44, P=0.001, respectively). Pairwise comparisons of R₂CHA₂DS₂-VASc (area under the curve [AUC]: 0.870, 95% confidence interval [CI]: 0.776-0.964; P<0.001), ES II (AUC: 0.801, 95% CI: 0.703-0.899; P<0.001), and TAVR scores (AUC: 0.730, 95% CI: 0.610-852; P=0.002) showed similar accuracy for predicting mortality. R₂CHA₂DS₂-VASc score is an independent predictor of mortality in multivariable Cox regression analysis. A cutoff value of six for R₂CHA₂DS₂-VASc score showed a sensitivity of 74% and a specificity of 89% for predicting mid-to-long-term mortality.

Conclusion

R₂CHA₂DS₂-VASc score, easily calculated from clinical parameters, is associated with prediction of mid-to-longterm mortality in patients undergoing TAVR.

German Aortic Valve Score in Risk Assessment for Surgical Aortic Valve Replacement in a Brazilian Center

OBJECTIVE

To test the German Aortic Valve (GAV) score at our university hospital in patients undergoing isolated aortic valve replacement (AVR).

METHODS

A total of 224 patients who underwent isolated conventional AVR between January 2015 and December 2018 were included. Patients with concomitant procedures and transcatheter aortic valve implantation were excluded. Patients' data were collected and analyzed retrospectively. Patients' risk scores were calculated according to criteria described by GAV score. Sensitivity, specificity, and accuracy (area under the ROC curve [AUC]) were also calculated. The calibration of the model was tested by the Hosmer-Lemeshow method.

RESULTS

The mortality rate was 8.04% (18 patients). The patients' mean age was 58.2±19.3 years and 25% of them were female (56 patients). Mean GAV score was 1.73±5.86 (min: 0.0; max: 3.53). The GAV score showed excellent discriminative capacity (AUC 0.925, 95% confidence interval 0.882-0.956; P<0.001). The cutoff "1.8" turned out to be the best discriminatory point with the best combination of sensitivity (88.9%) and specificity (75.7%) to predict operative death. Hosmer-Lemeshow method revealed a P-value of 0.687, confirming a good calibration of the model.

CONCLUSION

The GAV score applies to our population with high predictive accuracy.

Effects of Treatment of Metabolic Acidosis in CKD: A Systematic Review and Meta-Analysis

BACKGROUND AND OBJECTIVES

Metabolic acidosis is associated with progression of CKD and has significant adverse effects on muscle and bone. A systematic review and meta-analysis was conducted to evaluate the benefits and risks of metabolic acidosis treatment with oral alkali supplementation or a reduction of dietary acid intake in those with CKD.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

MEDLINE, Embase, and Cochrane CENTRAL were searched for relevant trials in patients with stage 3-5 CKD and metabolic acidosis (<22 mEq/L) or low-normal serum bicarbonate (22-24 mEq/L). Data were pooled in a meta-analysis with results expressed as weighted mean difference for continuous outcomes and relative risk for categorical outcomes with 95% confidence intervals (95% CIs), using a random effects model. Study quality and strength of evidence were assessed using Cochrane risk of bias and the Grading of Recommendations Assessment, Development and Evaluation criteria.

RESULTS

Fourteen clinical trials were included (n=1394 participants). Treatment of metabolic acidosis with oral alkali supplementation or a reduction of dietary acid intake increased serum bicarbonate levels (14 studies, 1378 patients, mean difference 3.33 mEq/L, 95% CI, 2.37 to 4.29) and resulted in a slower decline in eGFR (13 studies, 1329 patients, mean difference -3.28 ml/min per 1.73 m2, 95% CI, -4.42 to -2.14; moderate certainty) and a reduction in urinary albumin excretion (very-low certainty), along with a reduction in the risk of progression to ESKD (relative risk, 0.32; 95% CI, 0.18 to 0.56; low certainty). Oral alkali supplementation was associated with worsening hypertension or the requirement for increased antihypertensive therapy (very-low certainty).

CONCLUSIONS

Low-to-moderate certainty evidence suggest that oral alkali supplementation or a reduction in dietary acid intake may slow the rate of kidney function decline and potentially reduce the risk of ESKD in patients with CKD and metabolic acidosis.

Evolution Over Time of Volume Status and PD-Related Practice Patterns in an Incident Peritoneal Dialysis Cohort

BACKGROUND AND OBJECTIVES

Volume overload is frequent in prevalent patients on kidney replacement therapies and is associated with outcome. This study was devised to follow-up volume status of an incident population on peritoneal dialysis (PD) and to relate this to patient-relevant outcomes.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

This prospective cohort study was implemented in 135 study centers from 28 countries. Incident participants on PD were enrolled just before the actual PD treatment was started. Volume status was measured using bioimpedance spectroscopy before start of PD and thereafter in 3-month intervals, together with clinical and laboratory parameters, and PD prescription. The association of volume overload with time to death was tested using a competing risk Cox model.

RESULTS

In this population of 1054 participants incident on PD, volume overload before start of PD amounted to 1.9±2.3 L, and decreased to 1.2±1.8 L during the first year. At all time points, men and participants with diabetes were at higher risk to be volume overloaded. Dropout from PD during 3 years of observation by transfer to hemodialysis or transplantation (23% and 22%) was more prevalent than death (13%). Relative volume overload >17.3% was independently associated with higher risk of death (adjusted hazard ratio, 1.59; 95% confidence interval, 1.08 to 2.33) compared with relative volume overload ≤17.3%. Different practice patterns were observed between regions with respect to proportion of patients on PD versus hemodialysis, selection of PD modality, and prescription of hypertonic solutions.

CONCLUSIONS

In this large cohort of incident participants on PD, with different treatment practices across centers and regions, we found substantial volume overload already at start of dialysis. Volume overload improved over time, and was associated with survival.

Sodium Zirconium Cyclosilicate among Individuals with Hyperkalemia: A 12-Month Phase 3 Study

BACKGROUND AND OBJECTIVES

Oral sodium zirconium cyclosilicate (formerly ZS-9) binds and removes potassium via the gastrointestinal tract. Sodium zirconium cyclosilicate-associated restoration and maintenance of normokalemia and adverse events were evaluated in a two-part, open label, phase 3 trial.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

In the correction phase, adult outpatients with plasma potassium ≥5.1 mmol/L (i-STAT Point-of-Care) received sodium zirconium cyclosilicate 10 g three times daily for 24-72 hours until normokalemic (potassium =3.5-5.0 mmol/L). Qualifying participants entered the ≤12-month maintenance phase and received sodium zirconium cyclosilicate 5 g once daily titrated to maintain normokalemia without dietary or medication restrictions. Prespecified primary end points were restoration of normal serum potassium values (3.5-5.0 mmol/L) during the correction phase and maintenance of serum potassium ≤5.1 mmol/L during the maintenance phase. Adverse events were assessed throughout.

RESULTS

Of 751 participants, 746 (99%) achieved normokalemia during the correction phase (mean serum potassium =4.8 mmol/L; 95% confidence interval, 4.7 to 4.8) and entered the maintenance phase; 466 (63%) participants completed the 12-month trial. Participants were predominantly white, men, and age ≥65 years old; 74% had an eGFR<60 ml/min per 1.73 m², and 65% used renin-angiotensin-aldosterone system inhibitors. Mean time on sodium zirconium cyclosilicate was 286 days. Mean daily sodium zirconium cyclosilicate dose was 7.2 g (SD=2.6). Over months 3-12, mean serum potassium was 4.7 mmol/L (95% confidence interval, 4.6 to 4.7); mean serum potassium values ≤5.1 and ≤5.5 mmol/L were achieved by 88% and 99% of participants, respectively. Of 483 renin-angiotensin-aldosterone system inhibitor users at baseline, 87% continued or had their dose increased; 11% discontinued. Among 263 renin-angiotensin-aldosterone system inhibitor-naïve participants, 14% initiated renin-angiotensin-aldosterone system inhibitor therapy. Overall, 489 (66%) participants experienced adverse events during the maintenance phase, and 22% experienced a serious adverse event. Of eight (1%) deaths, none were considered related to sodium zirconium cyclosilicate. Nine (1%) and 34 (5%) participants experienced serum potassium <3.0 and 3.0-3.4 mmol/L, respectively.

CONCLUSIONS

After achieving normokalemia, individualized once daily sodium zirconium cyclosilicate was associated with maintenance of normokalemia without substantial renin-angiotensin-aldosterone system inhibitor changes for ≤12 months.

Postdialysis Hypokalemia and All-Cause Mortality in Patients Undergoing Maintenance Hemodialysis

BACKGROUND AND OBJECTIVES

Almost half of patients on dialysis demonstrate a postdialysis serum potassium ≤3.5 mEq/L. We aimed to examine the relationship between postdialysis potassium levels and all-cause mortality.

DESIGN, SETTING, PATIENTS, & MEASUREMENTS

We conducted a cohort study of 3967 participants on maintenance hemodialysis from the Dialysis Outcomes and Practice Patterns Study in Japan (2009-2012 and 2012-2015). Postdialysis serum potassium was measured repeatedly at 4-month intervals and used as a time-varying variable. We estimated the hazard ratio of all-cause mortality rate using Cox hazard regression models, with and without adjusting for time-varying predialysis serum potassium. Models were adjusted for baseline characteristics and time-varying laboratory parameters. We also analyzed associations of combinations of pre- and postdialysis potassium with mortality.

RESULTS

The age of participants at baseline was 65±12 years (mean±SD), 2552 (64%) were men, and 96% were treated with a dialysate potassium level of 2.0 to <2.5 mEq/L. The median follow-up period was 2.6 (interquartile range, 1.3-2.8) years. During the follow-up period, 562 (14%) of 3967 participants died, and the overall mortality rate was 6.7 per 100 person-years. Compared with postdialysis potassium of 3.0 to <3.5 mEq/L, the hazard ratios of postdialysis hypokalemia (<3.0 mEq/L) were 1.84 (95% confidence interval, 1.44 to 2.34) in the unadjusted model, 1.44 (95% confidence interval, 1.14 to 1.82) in the model without adjusting for predialysis serum potassium, and 1.10 (95% confidence interval, 0.84 to 1.44) in the model adjusted for predialysis serum potassium. The combination of pre- and postdialysis hypokalemia was associated with the highest mortality risk (hazard ratio, 1.72; 95% confidence interval, 1.35 to 2.19, reference; pre- and postdialysis nonhypokalemia).

CONCLUSIONS

Postdialysis hypokalemia was associated with mortality, but this association was not independent of predialysis potassium.

Major Adverse Kidney Events in Pediatric Sepsis

BACKGROUND AND OBJECTIVES

Major adverse kidney events, a composite of death, new kidney replacement therapy, or persistent kidney dysfunction, is a potential patient-centered outcome for clinical trials in sepsis-associated kidney injury. We sought to determine the incidence of major adverse kidney events within 30 days and validate this end point in pediatric sepsis.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

We conducted a retrospective observational study using the Pediatric Health Information Systems Plus database of patients >6 months to <18 years old with a diagnosis of severe sepsis/septic shock; orders for bacterial blood culture, antibiotics, and at least one fluid bolus on hospital day 0/1; and known hospital disposition between January 2007 and December 2011. The primary outcome was incidence of major adverse kidney events within 30 days. Major adverse kidney events within 30 days were validated against all-cause mortality at hospital discharge, hospital length of stay, total hospital costs, hospital readmission within 30 days and 1 year, and lowest eGFR between 3 months and 1 year after discharge. We reported incidence of major adverse kidney events within 30 days with 95% confidence intervals using robust SEM and used multivariable logistic regression to test the association of major adverse kidney events within 30 days with hospital costs and mortality.

RESULTS

Of 1685 admissions, incidence of major adverse kidney events within 30 days was 9.6% (95% confidence interval, 8.1% to 11.0%), including 4.5% (95% confidence interval, 3.5% to 5.4%) death, 1.7% (95% confidence interval, 1.1% to 2.3%) kidney replacement therapy, and 5.8% (95% confidence interval, 4.7% to 6.9%) persistent kidney dysfunction. Patients with versus without major adverse kidney events within 30 days had higher all-cause mortality at hospital discharge (28% versus 1%; P<0.001), higher total hospital costs ($61,188; interquartile range, $21,272-140,356 versus $28,107; interquartile range, $13,056-72,697; P<0.001), and higher proportion with eGFR<60 ml/min per 1.73 m² between 3 months and 1 year after discharge (19% versus 4%; P=0.001). Major adverse kidney events within 30 days was not associated with length of stay or readmissions.

CONCLUSIONS

In children with sepsis, major adverse kidney events within 30 days are common, feasible to measure, and a promising end point for future clinical trials.

Hypoglycemia in People with Type 2 Diabetes and CKD

BACKGROUND AND OBJECTIVES

Among people with diabetes mellitus, CKD may promote hypoglycemia through altered clearance of glucose-lowering medications, decreased kidney gluconeogenesis, and blunted counter-regulatory response. We conducted a prospective observational study of hypoglycemia among 105 individuals with type 2 diabetes treated with insulin or a sulfonylurea using continuous glucose monitors.

DESIGN, SETTING, PARTICIPANTS & MEASUREMENTS

We enrolled 81 participants with CKD, defined as eGFR<60 ml/min per 1.73 m², and 24 control participants with eGFR≥60 ml/min per 1.73 m² frequency-matched on age, duration of diabetes, hemoglobin A1c, and glucose-lowering medications. Each participant wore a continuous glucose monitor for two 6-day periods. We examined rates of sustained level 1 hypoglycemia (<70 mg/dl) and level 2 hypoglycemia (<54 mg/dl) among participants with CKD. We then tested differences compared with control participants as well as a second control population (n=73) using Poisson and linear regression, adjusting for age, sex, and race.

RESULTS

Over 890 total days of continuous glucose monitoring, participants with CKD were observed to have 255 episodes of level 1 hypoglycemia, of which 68 episodes reached level 2 hypoglycemia. Median rate of hypoglycemic episodes was 5.3 (interquartile range, 0.0-11.7) per 30 days and mean time spent in hypoglycemia was 28 (SD 37) minutes per day. Hemoglobin A1c and the glucose management indicator were the main clinical correlates of time in hypoglycemia (adjusted differences 6 [95% confidence interval, 2 to 10] and 13 [95% confidence interval, 7 to 20] fewer minutes per day per 1% higher hemoglobin A1c or glucose management indicator, respectively). Compared with control populations, participants with CKD were not observed to have significant differences in time in hypoglycemia (adjusted differences 4 [95% confidence interval, -12 to 20] and -12 [95% confidence interval, -29 to 5] minutes per day).

CONCLUSIONS

Among people with type 2 diabetes and moderate to severe CKD, hypoglycemia was common, particularly with tighter glycemic control, but not significantly different from groups with similar clinical characteristics and preserved eGFR.

Safety of Dynamic Intravenous Iron Administration Strategies in Hemodialysis Patients

BACKGROUND AND OBJECTIVES

Intravenous iron therapy for chronic anemia management is largely driven by dosing protocols that differ in intensity with respect to dosing approach (i.e., dose, frequency, and duration). Little is known about the safety of these protocols.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

Using clinical data from a large United States dialysis provider linked to health care utilization data from Medicare, we constructed a cohort of patients with ESKD aged ≥65 years who initiated and continued center-based hemodialysis for ≥90 days between 2009 and 2012, and initiated at least one of the five common intravenous iron administration strategies; ranked by intensity (the amount of iron given at moderate-to-high iron indices), the order of strategies was 3 (least intensive), 2 (less intensive), 1 (reference), 4 (more intensive), and 5 (most intensive). We estimated the effect of continuous exposure to these strategies on cumulative risks of mortality and infection-related events with dynamic Cox marginal structural models.

RESULTS

Of 13,249 eligible patients, 1320 (10%) died and 1627 (12%) had one or more infection-related events during the 4-month follow-up. The most and least commonly initiated strategy was strategy 2 and 5, respectively. Compared with the reference strategy 1, more intensive strategies (4 and 5) demonstrated a higher risk of all-cause mortality (e.g., most intensive strategy 5: 60-day risk difference: 1.3%; 95% confidence interval [95% CI], 0.8% to 2.1%; 120-day risk difference: 3.1%; 95% CI, 1.0% to 5.6%). Similarly, higher risks were observed for infection-related morbidity and mortality among more intensive strategies (e.g., strategy 5: 60-day risk difference: 1.8%; 95% CI, 1.2% to 2.6%; 120-day risk difference: 4.3%; 95% CI, 2.2% to 6.8%). Less intensive strategies (2 and 3) demonstrated lower risks of all-cause mortality and infection-related events.

CONCLUSIONS

Among dialysis patients surviving 90 days, subsequent intravenous iron administration strategies promoting more intensive iron treatment at moderate-to-high iron indices levels are associated with higher risks of mortality and infection-related events.

Estimated Glomerular Filtration Rate and the Risk of Cancer

BACKGROUND AND OBJECTIVES

Community-based reports regarding eGFR and the risk of cancer are conflicting. We here explore plausible links between kidney function and cancer incidence in a large Scandinavian population-based cohort.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

In the Stockholm Creatinine Measurements project, we quantified the associations of baseline eGFR with the incidence of cancer among 719,033 Swedes ages ≥40 years old with no prior history of cancer. Study outcomes were any type and site-specific cancer incidence rates on the basis of International Classification of Diseases-10 codes over a median follow-up of 5 years. To explore the possibility of detection bias and reverse causation, we divided the follow-up time into different time periods (≤12 and >12 months) and estimated risks for each of these intervals.

RESULTS

In total, 64,319 cases of cancer (affecting 9% of participants) were detected throughout 3,338,226 person-years. The relationship between eGFR and cancer incidence was U shaped. Compared with eGFR of 90-104 ml/min, lower eGFR strata associated with higher cancer risk (adjusted hazard ratio, 1.08; 95% confidence interval, 1.05 to 1.11 for eGFR=30-59 ml/min and adjusted hazard ratio, 1.24; 95% confidence interval, 1.15 to 1.35 for eGFR<30 ml/min). Lower eGFR strata were significantly associated with higher risk of skin, urogenital, prostate, and hematologic cancers. Any cancer risk as well as skin (nonmelanoma) and urogenital cancer risks were significantly elevated throughout follow-up time, but they were higher in the first 12 months postregistration. Associations with hematologic and prostate cancers abrogated after the first 12 months of observation, suggesting the presence of detection bias and/or reverse causation.

CONCLUSIONS

There is a modestly higher cancer risk in individuals with mild to severe CKD driven primarily by skin and urogenital cancers, and this is only partially explained by bias.

The New Statistics for Better Science: Ask How Much, How Uncertain, and What Else is Known

The "New Statistics" emphasizes effect sizes, confidence intervals, meta-analysis, and the use of Open Science practices. We present 3 specific ways in which a New Statistics approach can help improve scientific practice: by reducing over-confidence in small samples, by reducing confirmation bias, and by fostering more cautious judgments of consistency. We illustrate these points through consideration of the literature on oxytocin and human trust, a research area that typifies some of the endemic problems that arise with poor statistical practice.

Etiology and Outcomes of Thrombotic Microangiopathies

BACKGROUND AND OBJECTIVES

Thrombotic microangiopathies constitute a diagnostic and therapeutic challenge. Secondary thrombotic microangiopathies are less characterized than primary thrombotic microangiopathies (thrombotic thrombocytopenic purpura and atypical hemolytic and uremic syndrome). The relative frequencies and outcomes of secondary and primary thrombotic microangiopathies are unknown.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

We conducted a retrospective study in a four-hospital institution in 564 consecutive patients with adjudicated thrombotic microangiopathies during the 2009-2016 period. We estimated the incidence of primary and secondary thrombotic microangiopathies, thrombotic microangiopathy causes, and major outcomes during hospitalization (death, dialysis, major cardiovascular events [acute coronary syndrome and/or acute heart failure], and neurologic complications [stroke, cognitive impairment, or epilepsy]).

RESULTS

We identified primary thrombotic microangiopathies in 33 of 564 patients (6%; thrombotic thrombocytopenic purpura: 18 of 564 [3%]; atypical hemolytic and uremic syndrome: 18 of 564 [3%]). Secondary thrombotic microangiopathies were found in 531 of 564 patients (94%). A cause was identified in 500 of 564 (94%): pregnancy (35%; 11 of 1000 pregnancies), malignancies (19%), infections (33%), drugs (26%), transplantations (17%), autoimmune diseases (9%), shiga toxin due to Escherichia coli (6%), and malignant hypertension (4%). In the 31 of 531 patients (6%) with other secondary thrombotic microangiopathies, 23% of patients had sickle cell disease, 10% had glucose-6-phosphate dehydrogenase deficiency, and 44% had folate deficiency. Multiple causes of thrombotic microangiopathies were more frequent in secondary than primary thrombotic microangiopathies (57% versus 19%; P<0.001), and they were mostly infections, drugs, transplantation, and malignancies. Significant differences in clinical and biologic differences were observed among thrombotic microangiopathy causes. During the hospitalization, 84 of 564 patients (15%) were treated with dialysis, 64 of 564 patients (11%) experienced major cardiovascular events, and 25 of 564 patients (4%) had neurologic complications; 58 of 564 patients (10%) died, but the rates of complications and death varied widely by the cause of thrombotic microangiopathies.

CONCLUSIONS

Secondary thrombotic microangiopathies represent the majority of thrombotic microangiopathies. Multiple thrombotic microangiopathies causes are present in one half of secondary thrombotic microangiopathies. The risks of dialysis, neurologic and cardiac complications, and death vary by the cause of thrombotic microangiopathies.

Secondhand Smoke and CKD

BACKGROUND AND OBJECTIVES

Active smoking is associated with higher risk of various diseases. However, the risk of CKD development in nonsmokers exposed to secondhand smoke is not well elucidated. We aimed to investigate the association between secondhand smoke exposure and the risk of CKD development among never-smokers.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

A total of 131,196 never-smokers with normal kidney function, who participated in the Korean Genome and Epidemiology Study from 2001 to 2014, were analyzed. The participants were classified into three groups on the basis of frequency of secondhand smoke exposure, assessed with survey questionnaires; no exposure, <3 days per week, and ≥3 days per week. The association between secondhand smoke and CKD, defined as eGFR<60 ml/min per 1.73 m², was examined in the cross-sectional analysis. In addition, the risk of incident CKD development was analyzed in a longitudinal cohort of 1948 participants without CKD at baseline, which was a subset of the main cohort.

RESULTS

The mean age of participants was 53 years, and 75% were women. Prevalent CKD was observed in 231 (1.8%), 64 (1.7%), and 2280 (2.0%) participants in the ≥3 days per week, <3 days per week, and no exposure groups. The odds ratio (OR) of prevalent CKD was significantly higher in the groups exposed to secondhand smoke than the no exposure group (<3 days per week: OR, 1.72; 95% confidence interval [95% CI], 1.30 to 2.27; and ≥3 days per week: OR, 1.44; 95% CI, 1.22 to 1.70). During a mean follow-up of 104 months, CKD occurred in 319 (16%) participants. Multivariable Cox analysis revealed that the risk for CKD development was higher in participants exposed to secondhand smoke than the no exposure group (<3 days per week: hazard ratio, 1.59; 95% CI, 0.96 to 2.65; and ≥3 days per week: hazard ratio, 1.66; 95% CI, 1.03 to 2.67).

CONCLUSIONS

Exposure to secondhand smoke was associated with a higher prevalence of CKD as well as development of incident CKD.

Urinary Potassium Excretion and Progression of CKD

BACKGROUND AND OBJECTIVES

Data on whether low or high urinary potassium excretion is associated with poor kidney outcome have been conflicting. The aim of this study was to clarify the association between urinary potassium excretion and CKD progression.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

We investigated the relationship between lower urinary potassium excretion and CKD progression and compared three urinary potassium indices among 1821 patients from the Korean Cohort Study for Outcome in Patients with CKD. Urinary potassium excretion was determined using spot urinary potassium-to-creatinine ratio, spot urinary potassium concentration, and 24-hour urinary potassium excretion. Patients were categorized into four groups according to quartiles of each urinary potassium excretion metric. The study end point was a composite of a ≥50% decrease in eGFR from baseline values and ESKD.

RESULTS

During 5326 person-years of follow-up, the primary outcome occurred in 392 (22%) patients. In a multivariable cause-specific hazard model, lower urinary potassium-to-creatinine ratio was associated with higher risk of CKD progression (adjusted hazard ratio, 1.47; 95% confidence interval, 1.01 to 2.12) comparing the lowest quartile with the highest quartile. Sensitivity analyses with other potassium metrics also showed consistent results in 855 patients who completed 24-hour urinary collections: adjusted hazard ratios comparing the lowest quartile with the highest quartile were 3.05 (95% confidence interval, 1.54 to 6.04) for 24-hour urinary potassium excretion, 1.95 (95% confidence interval, 1.05 to 3.62) for spot urinary potassium-to-creatinine ratio, and 3.79 (95% confidence interval, 1.51 to 9.51) for spot urinary potassium concentration.

CONCLUSIONS

Low urinary potassium excretion is associated with progression of CKD.

Clinical Outcomes of Failing to Dose-Reduce Cephalosporin Antibiotics in Older Adults with CKD

BACKGROUND AND OBJECTIVES

Current dosing recommendations for cephalosporin antibiotics are on the basis of pharmacokinetic studies and are frequently ignored in practice. This study was undertaken to investigate the clinical outcomes of failing to dose-reduce cephalosporin antibiotics in CKD.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

Retrospective cohort study conducted in Ontario, Canada using linked population-based health care databases. Nine thousand three hundred forty-seven outpatients (median age 83; interquartile range, 77-88 years; 57% women) with an eGFR<30 ml/min per 1.73 m2 and no prior history of dialysis were dispensed oral cephalexin, cefuroxime, or cefprozil between April of 2007 and March of 2016. Two thirds of the patients (6253 of 9347) received a higher than recommended daily dose of cephalexin (>1000 mg), cefuroxime (>500 mg), or cefprozil (>500 mg). The primary outcome was a hospital encounter (emergency room visit or hospital admission) with a condition listed as a possible side-effect of cephalosporins. Secondary outcomes were antibiotic treatment failure and all-cause mortality. All measures were assessed in the 30 days after cephalosporin initiation.

RESULTS

Patients who received a higher than recommended dose of a cephalosporin antibiotic were similar in multiple indicators of baseline health to patients who received a reduced dose. Overall, 6% of patients presented to hospital with a possible cephalosporin side-effect, 13% failed antibiotic treatment, and 3% died. Compared with a reduced dose, receiving a higher dose of antibiotic was not associated with a different rate of side-effects (adjusted odds ratio, 1.00; 95% confidence interval, 0.84 to 1.20), treatment failure (1.01; 0.88 to 1.15), or death (0.99; 0.76 to 1.29).

CONCLUSIONS

In this study we failed to demonstrate any association between the dose of cephalosporin antibiotic administered to elderly patients with CKD and the risk of side-effects leading to hospitalization, treatment failure, or mortality.

Association of Continuation of Loop Diuretics at Hemodialysis Initiation with Clinical Outcomes

BACKGROUND AND OBJECTIVES

Loop diuretics are commonly used to manage nondialysis-dependent CKD. Despite benefits of augmented urine output, loop diuretics are often discontinued after dialysis initiation. Here, we assessed the association of the early decision to continue loop diuretics at hemodialysis start with clinical outcomes during the first year of dialysis.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

We considered all patients on in-center hemodialysis at a large dialysis organization (2006-2013) with Medicare Part A and D benefits who had an active supply of a loop diuretic at dialysis initiation (n=11,297). Active therapy was determined on the basis of whether loop diuretic prescription was refilled after dialysis initiation and within 30 days of exhaustion of prior supply. Patients were followed under an intention-to-treat paradigm for up to 12 months for rates of death, hospitalization, and intradialytic hypotension and mean monthly values of interdialytic weight gain, serum potassium, predialysis systolic BP, and ultrafiltration rates.

RESULTS

We identified 5219 patients who refilled a loop diuretic and 6078 eligible controls who did not. After adjustments for patient mix and clinical differences, continuation of loop diuretics was associated with lower hospitalization (adjusted incidence rate ratio, 0.93; 95% confidence interval, 0.89 to 0.98) and intradialytic hypotension (adjusted incidence rate ratio, 0.95; 95% confidence interval, 0.92 to 0.99) rates, no difference in death rate (adjusted hazard ratio, 0.92; 95% confidence interval, 0.84 to 1.01), and lower interdialytic weight gain (P=0.03).

CONCLUSIONS

Continuation of loop diuretics after hemodialysis initiation was associated with lower rates of hospitalization and intradialytic hypotension as well as lower interdialytic weight gain, but there was no difference in mortality over the first year of dialysis.

Facility-Level Variations in Kidney Disease Care among Veterans with Diabetes and CKD

BACKGROUND AND OBJECTIVES

Facility-level variation has been reported among veterans receiving care for various diseases. We studied the frequency and facility-level variations of guideline-recommended practices in patients with diabetes and CKD.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

Patients with diabetes and concomitant CKD (eGFR 15-59 ml/min per 1.73 m2, measured twice, 90 days apart) receiving care in 130 facilities across the Veterans Affairs Health Care System were included (n=281,223). We studied the proportions of patients (facility-level) receiving recommended core measures and facility-level variations of these study outcomes using median rate ratios, adjusting for various patient and provider-level factors. Median rate ratio quantifies the degree to which care may vary for similar patients receiving care at two randomly chosen facilities, with <1 being no variation and >1.2 as substantial variation between the facilities. Study outcomes included measurement of urine albumin-to-creatinine ratio/urine protein-to-creatinine ratio and blood hemoglobin concentration, prescription of statins and angiotensin-converting enzyme inhibitors/angiotensin receptor blockers, BP<140/90 mm Hg, and referral to a Veterans Affairs nephrologist (only for those with eGFR<30 ml/min per 1.73 m2).

RESULTS

Among those with eGFR 30-59 ml/min per 1.73 m2, proportion of patients receiving recommended core measures (median and interquartile range across facilities) were 37% (22%-47%) for urine albumin-to-creatinine ratio/urine protein-to-creatinine ratio, 74% (72%-79%) for hemoglobin measurement, 66% (62%-69%) for angiotensin-converting enzyme inhibitor/angiotensin receptor blocker prescription, 85% (74%-87%) for statin prescription, 47% (42%-53%) for achieving BP<140/90 mm Hg, and 13% (7%-16%) for meeting all outcome measures. Adjusted median rate ratios (95% confidence intervals) were 5.2 (4.1 to 6.4), 2.4 (2.1 to 2.6), 1.3 (1.2 to 1.3), 1.2 (1.2 to 1.3), 1.4 (1.3 to 1.4), and 4.1 (3.3 to 5.0), respectively. Median rate ratios were qualitatively similar in an analysis restricted to those with eGFR 15-29 ml/min per 1.73 m2.

CONCLUSIONS

Among patients with diabetes and CKD, at facility-level, ordering of laboratory tests, and scheduling of nephrology referrals in eligible patients remains suboptimal, with substantial variations across facilities.

Association of Monoclonal Gammopathy with Progression to ESKD among US Veterans

BACKGROUND AND OBJECTIVES

Whether patients with monoclonal protein are at a higher risk for progression of kidney disease is not known. The goal of this study was to measure the association of monoclonal protein with progression to ESKD.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

This was a retrospective cohort study of 2,156,317 patients who underwent serum creatinine testing between October 1, 2000 and September 30, 2001 at a Department of Veterans Affairs medical center, among whom 21,898 had paraprotein testing within 1 year before or after cohort entry. Progression to ESKD was measured using linked data from the US Renal Data System.

RESULTS

Overall, 1,741,707 cohort members had an eGFR≥60 ml/min per 1.73 m2, 283,988 had an eGFR of 45-59 ml/min per 1.73 m2, 103,123 had an eGFR of 30-44 ml/min per 1.73 m2 and 27,499 had an eGFR of 15-29 ml/min per 1.73 m2. The crude incidence of ESKD ranged from 0.7 to 80 per 1000 person-years from the highest to lowest eGFR category. Patients with low versus preserved eGFR were more likely to be tested for monoclonal protein but no more likely to have a positive test result. In adjusted analyses, a positive versus negative test result was associated with a higher risk of ESKD among patients with an eGFR≥60 ml/min per 1.73 m2 (hazard ratio, 1.67; 95% confidence interval, 1.22 to 2.29) and those with an eGFR of 15-29 ml/min per 1.73 m2 (hazard ratio, 1.38; 95% confidence interval, 1.07 to 1.77), but not among those with an eGFR of 30-59 ml/min per 1.73 m2. Progression to ESKD was attributed to a monoclonal process in 21 out of 76 versus seven out of 174 patients with monoclonal protein and preserved versus severely reduced eGFR at cohort entry.

CONCLUSIONS

The detection of monoclonal protein provides little information on ESKD risk for most patients with a low eGFR. Further study is required to better understand factors contributing to a positive association of monoclonal protein with ESKD risk in patients with preserved and severely reduced levels of eGFR.

Kidney Biopsy-Related Complications in Hospitalized Patients with Acute Kidney Disease

BACKGROUND AND OBJECTIVES

Patients are informed of the risk of kidney biopsy-related complications using data from nonhospitalized patients, which may underestimate the risk for hospitalized patients. We evaluated the rate and risk factors of kidney biopsy-related complications in hospitalized patients with acute kidney disease (AKD) to better estimate the risk in this population.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

We used data from the Yale biopsy cohort to evaluate rates of kidney biopsy-related complications including adjudicated procedure-related bleeding requiring blood transfusions or angiographic interventions, medium- or large-sized hematomas, reimaging after biopsy including abdominal ultrasonography or computed tomography, and death in hospitalized patients with AKD (including AKI). We evaluated univariable and multivariable association of risk factors with transfusions. We compared rates of complications between hospitalized and nonhospitalized patients.

RESULTS

Between 2015 and 2017, 159 hospitalized patients underwent a kidney biopsy for AKD evaluation, of which 80 (51%) had stage 1 AKI, 42 (27%) had stage 2 (or higher) AKI, and 27 (17%) had AKD (without AKI). Of these, 12 (8%; 95% confidence interval [95% CI], 5% to 15%) required a transfusion, three (2%; 95% CI, 1% to 5%) required an intervention, 11 (7%; 95% CI, 4% to 12%) had hematoma, and 31 (20%; 95% CI, 14% to 26%) required reimaging after biopsy. Of the four (3%; 95% CI, 1% to 6%) deaths during hospitalization, none were related to the biopsy. Female sex, lower platelet count, and higher BUN were associated with postbiopsy transfusions on univariable and multivariable analyses. Trainee as proceduralist and larger needle gauge were associated with transfusions in univariable, but not multivariable, analysis. Nonhospitalized patients had lower rates of transfusion than hospitalized patients, although the latter also had lower prebiopsy hemoglobin and greater surveillance after biopsy.

CONCLUSIONS

Hospitalized patients experience higher risk of postbiopsy complications than previously reported and several factors, such as lower platelet count, female sex, and higher BUN, are associated with this risk.

Vascular Dysfunction, Oxidative Stress, and Inflammation in Autosomal Dominant Polycystic Kidney Disease

BACKGROUND AND OBJECTIVES

Both increased arterial stiffness and vascular endothelial dysfunction are evident in patients with autosomal dominant polycystic kidney disease, even early in the course of the disease when kidney function in preserved. Vascular dysfunction in autosomal dominant polycystic kidney disease is thought to be related to vascular oxidative stress and inflammation, but direct evidence is lacking.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

We assessed carotid-femoral pulse-wave velocity (arterial stiffness) and brachial artery flow-mediated dilation (vascular endothelial function) in participants with early-stage autosomal dominant polycystic kidney disease (eGFR≥60 ml/min per 1.73 m2) and a history of controlled hypertension and in healthy controls. Brachial artery flow-mediated dilation was also assessed after infusion of ascorbic acid to inhibit vascular oxidative stress compared with saline. Vascular endothelial cells were collected from a peripheral vein to measure expression of proteins, and circulating markers were also assessed by ELISA or liquid chromatography-tandem mass spectrometry.

RESULTS

In total, 61 participants with autosomal dominant polycystic kidney disease (34±9 years old [mean±SD]) and 19 healthy controls (30±5 years old) were studied. Carotid-femoral pulse-wave velocity was higher in participants with autosomal dominant polycystic kidney disease compared with healthy controls (650±131 versus 562±81 cm/s; P=0.007). Brachial artery flow-mediated dilation was 8.2%±5.8% in participants with autosomal dominant polycystic kidney disease and 10.8%±4.7% in controls (P=0.08). Among participants with autosomal dominant polycystic kidney disease, flow-mediated dilation increased from 7.7%±4.5% to 9.4%±5.2% with ascorbic acid, a difference of 1.72 (95% confidence interval, 0.80 to 2.63), whereas in control participants, flow-mediated dilation decreased nonsignificantly from 10.8%±4.7% to 10.6%±5.4%, a difference of -0.20 (95% confidence interval, -1.24 to 0.84; P interaction =0.02). Endothelial cell protein expression of NF-κB was greater in participants with autosomal dominant polycystic kidney disease (0.48±0.12 versus 0.41±0.10 [intensity versus human umbilical vein endothelial cell control]; P=0.03). However, circulating oxidative stress markers and bioactive lipid mediators did not significantly differ according to the autosomal dominant polycystic kidney disease diagnosis.

CONCLUSIONS

These results provide support for the hypothesis that vascular oxidative stress and inflammation develop with autosomal dominant polycystic kidney disease.

PODCAST

This article contains a podcast at https://www.asn-online.org/media/podcast/CJASN/2018_09_18_CJASNPodcast_18_10_.mp3.

The Effect of Increasing Dialysate Magnesium on Serum Calcification Propensity in Subjects with End Stage Kidney Disease: A Randomized, Controlled Clinical Trial

BACKGROUND AND OBJECTIVES

Serum calcification propensity is a novel functional test that quantifies the functionality of the humeral system of calcification control. Serum calcification propensity is measured by T50, the time taken to convert from primary to secondary calciprotein particle in the serum. Lower T50 represents higher calcification propensity and is associated with higher risk of cardiovascular events and death in patients with ESKD. Increasing magnesium in serum increases T50, but so far, no clinical trials have investigated whether increasing serum magnesium increases serum calcification propensity in subjects with ESKD.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

We conducted a single-center, randomized, double-blinded, parallel group, controlled clinical trial, in which we examined the effect of increasing dialysate magnesium from 1.0 to 2.0 mEq/L for 28 days compared with maintaining dialysate magnesium at 1.0 mEq/L on T50 in subjects undergoing hemodialysis for ESKD. The primary end point was the value of T50 at the end of the intervention.

RESULTS

Fifty-nine subjects were enrolled in the trial, and of these, 57 completed the intervention and were analyzed for the primary outcome. In the standard dialysate magnesium group, T50 was 233±81 minutes (mean±SD) at baseline (mean of days -7 and 0) and 229±93 minutes at follow-up (mean of days 21 and 28), whereas in the high dialysate magnesium group, T50 was 247±69 minutes at baseline and 302±66 minutes at follow-up. The difference in T50 between the two groups at follow-up (primary analysis) was 73 minutes (between-group difference; 95% confidence interval, 30 to 116; P<0.001), and the between-group difference in serum magnesium was 0.88 mg/dl (95% confidence interval, 0.66 to 1.10; P=0.001).

CONCLUSIONS

Increasing dialysate magnesium increases T50 and hence, decreases calcification propensity in subjects undergoing maintenance hemodialysis.

PODCAST

This article contains a podcast at https://www.asn-online.org/media/podcast/CJASN/2018_08_21_CJASNPodcast_18_9_B.mp3.

Intravenous Epoetin Alfa-epbx versus Epoetin Alfa for Treatment of Anemia in End-Stage Kidney Disease

BACKGROUND AND OBJECTIVES

This study was conducted to compare the safety and efficacy of intravenous epoetin alfa-epbx, an epoetin alfa biosimilar, to epoetin alfa in patients on hemodialysis with ESKD and anemia.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

In this 24-week, multicenter, double-blind comparative efficacy and safety study, 612 patients on hemodialysis with ESKD and anemia who had stable hemoglobin and were receiving stable doses of intravenous epoetin alfa were randomized (1:1) to intravenous epoetin alfa or epoetin alfa-epbx. Dosing was adjusted according to the epoetin alfa prescribing information. The coprimary efficacy end points were the least squares mean difference between the two treatments in mean weekly hemoglobin level and mean weekly epoetin dose per kilogram of body weight during the last 4 weeks of treatment.

RESULTS

The least squares mean difference between epoetin alfa-epbx and epoetin alfa in weekly hemoglobin was -0.12 g/dl and the 95% confidence interval (-0.25 to 0.01) was contained within the prespecified equivalence margin (-0.5 to 0.5 g/dl). The least squares mean difference between epoetin alfa-epbx and epoetin alfa in weekly epoetin dose per kilogram of body weight was 0.37 U/kg per week, and the 95% confidence interval (-10.40 to 11.13) was contained within the prespecified equivalence margin (-45 to 45 U/kg per week). Incidences of adverse events (77.1% versus 75.3%), serious adverse events (24.9% versus 27.0%), and deaths (n=5 versus 6) were similar between the epoetin alfa-epbx and epoetin alfa groups, respectively. Five patients tested positive for anti-recombinant human erythropoietin antibodies at baseline, and two additional patients (n=1 per group) developed anti-recombinant human erythropoietin antibodies while on study treatment. All patients tested negative for neutralizing antibodies, and no patient in either group experienced an event of pure red cell aplasia.

CONCLUSIONS

This 24-week, comparative, clinical trial in patients on hemodialysis with ESKD and anemia demonstrated there is no clinically meaningful difference in efficacy or safety between epoetin alfa-epbx and epoetin alfa.

Risks and Benefits of Direct Oral Anticoagulants across the Spectrum of GFR among Incident and Prevalent Patients with Atrial Fibrillation

BACKGROUND AND OBJECTIVES

All randomized trials of direct oral anticoagulants in atrial fibrillation excluded patients with severe kidney disease. The safety and effectiveness of direct oral anticoagulants across the range of eGFR in real-world settings is unknown. Our objective is to quantify the risk of bleeding and benefit of ischemic stroke prevention for direct oral anticoagulants compared with warfarin in patients with atrial fibrillation with and without CKD.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

We created a propensity score-matched cohort of 3206 patients with atrial fibrillation and direct oral anticoagulant use and 3206 patients with atrial fibrillation using warfarin from October of 2010 to February of 2017 in an electronic health record (Geisinger Health System). The risks of bleeding and ischemic stroke were compared between direct oral anticoagulant and warfarin users using Cox proportional hazards regression, stratified by eGFR (≥60 and <60 ml/min per 1.73 m2).

RESULTS

The mean (SD) age of the 6412 participants was 72 (12) years, 47% were women, and average eGFR was 69 (21) ml/min per 1.73 m2. There were 1181 bleeding events and 466 ischemic strokes over 7391 person-years of follow-up. Compared with warfarin use, the hazard ratios (HRs) (95% confidence interval [95% CI]) of bleeding associated with direct oral anticoagulant use were 1.01 (0.88 to 1.17) and 1.23 (1.02 to 1.48) for those with eGFR≥60 and eGFR<60 ml/min per 1.73 m2, respectively (P-interaction=0.10). There was no difference between direct oral anticoagulant and warfarin users in the risk of ischemic stroke: HRs (95% CI) of 0.94 (0.74 to 1.18) and 1.02 (0.76 to 1.37) for those with eGFR≥60 and eGFR<60 ml/min per 1.73 m2, respectively (P-interaction=0.70). Similar findings were observed with individual drugs.

CONCLUSIONS

In a large health care system, patients with eGFR<60 ml/min per 1.73 m2 who took direct oral anticoagulants for atrial fibrillation had slightly higher risk of bleeding compared with those on warfarin, but similar benefits from prevention of ischemic stroke.

Self-Reported Tobacco, Alcohol, and Illicit Drug Use and Progression of Chronic Kidney Disease

BACKGROUND AND OBJECTIVES

Previous studies suggest that tobacco, alcohol, and illicit drug use is associated with CKD. We examined the associations of substance use with CKD progression and all-cause mortality among patients with CKD.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

The Chronic Renal Insufficiency Cohort Study is a prospective, longitudinal cohort study among 3939 participants with CKD in the United States. Self-reported tobacco smoking, alcohol drinking, marijuana use, and hard illicit drug (cocaine, heroin, or methamphetamine) use were obtained at baseline and annual follow-up visits. CKD progression was defined as incident ESKD or halving of eGFR. Substance use was modeled as the cumulative average exposure to capture both recent and long-term use in multivariable time-dependent Cox regression.

RESULTS

Over a median 5.5-year follow-up, 1287 participants developed CKD progression, and 1001 died. Baseline proportions of tobacco smoking, alcohol drinking, marijuana use, and hard illicit drug use were 13%, 20%, 33%, and 12%, respectively. Compared with nonsmoking throughout follow-up, multivariable-adjusted hazard ratios for persistent tobacco smoking were 1.02 (95% confidence interval, 0.86 to 1.21) for CKD progression and 1.86 (95% confidence interval, 1.54 to 2.24) for all-cause mortality. Compared with nondrinking throughout follow-up, multivariable-adjusted hazard ratios for persistent alcohol drinking were 1.06 (95% confidence interval, 0.88 to 1.29) for CKD progression and 0.73 (95% confidence interval, 0.58 to 0.91) for all-cause mortality. Compared with nonuse throughout follow-up, multivariable-adjusted hazard ratios for persistent marijuana use were 0.94 (95% confidence interval, 0.82 to 1.07) for CKD progression and 1.11 (95% confidence interval, 0.96 to 1.30) for all-cause mortality. Compared with nonuse throughout follow-up, multivariable-adjusted hazard ratios for persistent hard illicit drug use were 1.25 (95% confidence interval, 1.00 to 1.55) for CKD progression and 1.41 (95% confidence interval, 1.10 to 1.81) for all-cause mortality.

CONCLUSIONS

Hard illicit drug use is associated with higher risk of CKD progression and all-cause mortality, tobacco smoking is associated with higher risk of all-cause mortality, and alcohol drinking is associated with lower risk of all-cause mortality among patients with CKD.

Heroin Use Is Associated with AA-Type Kidney Amyloidosis in the Pacific Northwest

BACKGROUND AND OBJECTIVES

AA-type kidney amyloidosis is classically associated with chronic autoimmune or inflammatory disorders. However, some urban centers have reported a high prevalence of injection drug use among patients with kidney AA amyloidosis. Previous reports lack control groups to quantify associations and most predate the opioid epidemic in the United States.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

We conducted a case-control study of 38 patients with biopsy-confirmed kidney AA amyloidosis and 72 matched control individuals without this condition from two large hospital systems in Seattle, Washington. We ascertained the pattern and duration of heroin use by medical chart review and determined associations using logistic regression.

RESULTS

Among case patients, 95% had a prior history of heroin use, 87% had skin abscesses, and 76% and 27% had evidence of muscling and skin popping, respectively. After adjustment for age, race, sex, site, and year of biopsy, any heroin use (past or current) was associated with an estimated 170-times higher risk of kidney AA amyloidosis compared with no heroin use (95% confidence interval, 28 to 1018 times higher; P<0.001). Chronic autoimmune disorders were uncommon among case patients in this study. The median time to ESKD among patients with AA amyloidosis was 2.4 years (interquartile range, 0.5-7.5 years).

CONCLUSIONS

Injection heroin use is strongly associated with kidney AA amyloidosis in the Pacific Northwest. Unique aspects of heroin use, in particular geographic regions or frequent associated soft-tissue infections, may be an important cause of this progressive kidney disease.

Prevalence of Central Vein Stenosis in Patients Referred for Vein Mapping

BACKGROUND AND OBJECTIVES

Central vein stenosis is considered to be common in patients on hemodialysis but its exact prevalence is not known. In this study, we report the prevalence of central vein stenosis in patients with CKD referred for vein mapping.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

We conducted a retrospective study of adult patients who had bilateral upper extremity venographic vein mapping from September 1, 2011 to December 31, 2015. Patients with and without stenosis were compared for differences in clinical or demographic characteristics. Multiple logistic regression was used to identify independent associations between patient characteristics and central vein stenosis.

RESULTS

There were 525 patients who underwent venographic vein mapping during the study period, 27% of whom were referred before initiation of hemodialysis. The mean age (±SD) and body mass index were 59 (±15) years and 28 (±7), respectively. Women accounted for 45% of patients; 82% were black. The prevalence of central vein stenosis was 10% (95% confidence interval [95% CI], 8% to 13%) for the whole group, and 13% (95% CI, 10% to 17%) among patients with tunneled central venous dialysis catheters. Current use of tunneled hemodialysis catheters (odds ratio [OR], 14.5; 95% CI, 3.25 to 65.1), presence of cardiac rhythm devices (OR, 5.07; 95% CI, 1.82 to 14.11), previous history of fistula or graft (OR, 3.28; 95% CI, 1.58 to 6.7), and history of previous kidney transplant (OR, 18; 95% CI, 4.7 to 68.8) were independently associated with central vein stenosis.

CONCLUSIONS

In this population, the prevalence of central vein stenosis was 10% and was clustered among those with tunneled hemodialysis catheters, cardiac rhythm device, and previous history of dialysis access or transplant.

Incidence and Progression of Chronic Kidney Disease in Black and White Individuals with Type 2 Diabetes

BACKGROUND AND OBJECTIVES

Type 2 diabetes and associated CKD disproportionately affect blacks. It is uncertain if racial disparities in type 2 diabetes-associated CKD are driven by biologic factors that influence propensity to CKD or by differences in type 2 diabetes care.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

We conducted a post hoc analysis of 1937 black and 6372 white participants of the Action to Control Cardiovascular Risk in Diabetes (ACCORD) trial to examine associations of black race with change in eGFR and risks of developing microalbuminuria, macroalbuminuria, incident CKD (eGFR<60 ml/min per 1.73m2, ≥25% decrease from baseline eGFR, and eGFR slope <-1.6 ml/min per 1.73 m2 per year), and kidney failure or serum creatinine >3.3 mg/dl.

RESULTS

During a median follow-up that ranged between 4.4 and 4.7 years, 278 black participants (58 per 1000 person-years) and 981 white participants (55 per 1000 person-years) developed microalbuminuria, 122 black participants (16 per 1000 person-years) and 374 white participants (14 per 1000 person-years) developed macroalbuminuria, 111 black participants (21 per 1000 person-years) and 499 white participants (28 per 1000 person-years) developed incident CKD, and 59 black participants (seven per 1000 person-years) and 178 white participants (six per 1000 person-years) developed kidney failure or serum creatinine >3.3 mg/dl. Compared with white participants, black participants had lower risks of incident CKD (hazard ratio, 0.73; 95% confidence intervals, 0.57 to 0.92). There were no significant differences by race in eGFR decline or in risks of microalbuminuria, macroalbuminuria, and kidney failure or of serum creatinine >3.3 mg/dl.

CONCLUSIONS

Black participants enrolled in a randomized controlled trial had lower rates of incident CKD compared with white participants. Rates of eGFR decline, microalbuminuria, macroalbuminuria, and kidney failure did not vary by race.

Healthcare Utilization after Acute Kidney Injury in the Pediatric Intensive Care Unit

BACKGROUND AND OBJECTIVES

Little is known about the long-term burden of AKI in the pediatric intensive care unit. We aim to evaluate if pediatric AKI is associated with higher health service use post-hospital discharge.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

This is a retrospective cohort study of children (≤18 years old) admitted to two tertiary centers in Montreal, Canada. Only the first admission per patient was included. AKI was defined in two ways: serum creatinine alone or serum creatinine and/or urine output. The outcomes were 30-day, 1-year, and 5-year hospitalizations, emergency room visits, and physician visits per person-time using provincial administrative data. Univariable and multivariable Poisson regression were used to evaluate AKI associations with outcomes.

RESULTS

A total of 2041 children were included (56% male, mean admission age 6.5±5.8 years); 299 of 1575 (19%) developed AKI defined using serum creatinine alone, and when urine output was included in the AKI definition 355 of 1622 (22%) children developed AKI. AKI defined using serum creatinine alone and AKI defined using serum creatinine and urine output were both associated with higher 1- and 5-year hospitalization risk (AKI by serum creatinine alone adjusted relative risk, 1.42; 95% confidence interval, 1.12 to 1.82; and 1.80; 1.54 to 2.11, respectively [similar when urine output was included]) and higher 5-year physician visits (adjusted relative risk, 1.26; 95% confidence interval, 1.14 to 1.39). AKI was not associated with emergency room use after adjustments.

CONCLUSIONS

AKI is independently associated with higher hospitalizations and physician visits postdischarge.

Hydroxychloroquine Use and Risk of CKD in Patients with Rheumatoid Arthritis

BACKGROUND AND OBJECTIVES

Hydroxychloroquine is widely used in patients with rheumatoid arthritis. However, large-scale studies examining the long-term effects of hydroxychloroquine on the development of kidney disease in patients with rheumatoid arthritis are lacking. We aimed to assess the long-term association of hydroxychloroquine use with the risk of developing CKD in this population.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

We conducted an observational cohort study for patients with newly diagnosed rheumatoid arthritis who were enrolled prospectively in Taiwan's National Health Insurance Research Database between January 1, 2000 and December 31, 2013. We used multivariable Cox proportional hazard regression to analyze the association of hydroxychloroquine use with incident CKD.

RESULTS

A total of 2619 patients, including 1212 hydroxychloroquine users and 1407 hydroxychloroquine nonusers, were analyzed. Incident CKD was reported in 48 of 1212 hydroxychloroquine users and 121 of 1407 hydroxychloroquine nonusers. The incidence rate of CKD was lower in hydroxychloroquine users than in hydroxychloroquine nonusers (10.3 versus 13.8 per 1000 person-years). After multivariable adjustment, hydroxychloroquine users still had a lower risk of incident CKD (adjusted hazard ratio, 0.64; 95% confidence interval, 0.45 to 0.90; P=0.01) than hydroxychloroquine nonusers. The lower risk of subsequent CKD development was dose dependent and consistent across subgroup analyses.

CONCLUSIONS

Hydroxychloroquine use in patients with newly diagnosed rheumatoid arthritis is associated with a significantly lower risk of incident CKD compared with in nonusers.

Performance on the Nephrology In-Training Examination and ABIM Nephrology Certification Examination Outcomes

BACKGROUND AND OBJECTIVES

Medical specialty and subspecialty fellowship programs administer subject-specific in-training examinations to provide feedback about level of medical knowledge to fellows preparing for subsequent board certification. This study evaluated the association between the American Society of Nephrology In-Training Examination and the American Board of Internal Medicine Nephrology Certification Examination in terms of scores and passing status.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

The study included 1684 nephrology fellows who completed the American Society of Nephrology In-Training Examination in their second year of fellowship training between 2009 and 2014. Regression analysis examined the association between In-Training Examination and first-time Nephrology Certification Examination scores as well as passing status relative to other standardized assessments.

RESULTS

This cohort included primarily men (62%) and international medical school graduates (62%), and fellows had an average age of 32 years old at the time of first completing the Nephrology Certification Examination. An overwhelming majority (89%) passed the Nephrology Certification on their first attempt. In-Training Examination scores showed the strongest association with first-time Nephrology Certification Examination scores, accounting for approximately 50% of the total explained variance in the model. Each SD increase in In-Training Examination scores was associated with a difference of 30 U (95% confidence interval, 27 to 33) in certification performance. In-Training Examination scores also were significantly associated with passing status on the Nephrology Certification Examination on the first attempt (odds ratio, 3.46 per SD difference in the In-Training Examination; 95% confidence interval, 2.68 to 4.54). An In-Training Examination threshold of 375, approximately 1 SD below the mean, yielded a positive predictive value of 0.92 and a negative predictive value of 0.50.

CONCLUSIONS

American Society of Nephrology In-Training Examination performance is significantly associated with American Board of Internal Medicine Nephrology Certification Examination score and passing status.

Partial Consistency with Sparse Incidental Parameters

Penalized estimation principle is fundamental to high-dimensional problems. In the literature, it has been extensively and successfully applied to various models with only structural parameters. As a contrast, in this paper, we first apply this penalization principle to a linear regression model with a finite-dimensional vector of structural parameters and a high-dimensional vector of sparse incidental parameters. For the estimators of the structural parameters, we derive their consistency and asymptotic normality, which reveals an oracle property. However, the penalized estimators for the incidental parameters possess only partial selection consistency but not consistency. This is an interesting partial consistency phenomenon: the structural parameters are consistently estimated while the incidental ones cannot. For the structural parameters, also considered is an alternative two-step penalized estimator, which has fewer possible asymptotic distributions and thus is more suitable for statistical inferences. We further extend the methods and results to the case where the dimension of the structural parameter vector diverges with but slower than the sample size. A data-driven approach for selecting a penalty regularization parameter is provided. The finite-sample performance of the penalized estimators for the structural parameters is evaluated by simulations and a real data set is analyzed.

Central Blood Pressure and Cardiovascular Outcomes in Chronic Kidney Disease

BACKGROUND AND OBJECTIVES

Central BP measurements provide noninvasive measurement of aortic BP; our objectives were to examine the association of central and brachial BP measurements with risk of cardiovascular outcomes and mortality in patients with CKD and to determine the role of central BP measurement in conjunction with brachial BP in estimating cardiovascular risk.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

In a prospective, longitudinal study (the Chronic Renal Insufficiency Cohort), central BP was measured in participants with CKD using the SphygmoCorPVx System. Cox proportional hazards models were used for analyses.

RESULTS

Mean age of the participants (n=2875) was 60 years old. After a median follow-up of 5.5 years, participants in the highest quartile of brachial systolic BP (≥138 mm Hg) were at higher risk for the composite cardiovascular outcome (hazard ratio, 1.59; 95% confidence interval, 1.17 to 2.17; c statistic, 0.76) but not all-cause mortality (hazard ratio, 1.28; 95% confidence interval, 0.90 to 1.80) compared with those in the lowest quartile. Participants in the highest quartile of central systolic BP were also at higher risk for the composite cardiovascular outcome (hazard ratio, 1.69; 95% confidence interval, 1.24 to 2.31; c statistic, 0.76) compared with participants in the lowest quartile.

CONCLUSIONS

We show that elevated brachial and central BP measurements are both associated with higher risk of cardiovascular disease outcomes in patients with CKD. Measurement of central BP does not improve the ability to predict cardiovascular disease outcomes or mortality in patients with CKD compared with brachial BP measurement.

Fibroblast Growth Factor 23 Associates with Death in Critically Ill Patients

BACKGROUND AND OBJECTIVES

Dysregulated mineral metabolism is a common and potentially maladaptive feature of critical illness, especially in patients with AKI, but its association with death has not been comprehensively investigated. We sought to determine whether elevated plasma levels of the osteocyte-derived, vitamin D-regulating hormone, fibroblast growth factor 23 (FGF23), are prospectively associated with death in critically ill patients with AKI requiring RRT, and in a general cohort of critically ill patients with and without AKI.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

We measured plasma FGF23 and other mineral metabolite levels in two cohorts of critically ill patients (n=1527). We included 817 patients with AKI requiring RRT who enrolled in the ARF Trial Network (ATN) study, and 710 patients with and without AKI who enrolled in the Validating Acute Lung Injury biomarkers for Diagnosis (VALID) study. We hypothesized that higher FGF23 levels at enrollment are independently associated with higher 60-day mortality.

RESULTS

In the ATN study, patients in the highest compared with lowest quartiles of C-terminal (cFGF23) and intact FGF23 (iFGF23) had 3.84 (95% confidence interval, 2.31 to 6.41) and 2.08 (95% confidence interval, 1.03 to 4.21) fold higher odds of death, respectively, after adjustment for demographics, comorbidities, and severity of illness. In contrast, plasma/serum levels of parathyroid hormone, vitamin D metabolites, calcium, and phosphate were not associated with 60-day mortality. In the VALID study, patients in the highest compared with lowest quartiles of cFGF23 and iFGF23 had 3.52 (95% confidence interval, 1.96 to 6.33) and 1.93 (95% confidence interval, 1.12 to 3.33) fold higher adjusted odds of death.

CONCLUSIONS

Higher FGF23 levels are independently associated with greater mortality in critically ill patients.

Neurocognitive and Educational Outcomes in Children and Adolescents with CKD: A Systematic Review and Meta-Analysis

BACKGROUND AND OBJECTIVES

Poor cognition can affect educational attainment, but the extent of neurocognitive impairment in children with CKD is not well understood. This systematic review assessed global and domain-specific cognition and academic skills in children with CKD and whether these outcomes varied with CKD stage.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

Electronic databases were searched for observational studies of children with CKD ages 21 years old or younger that assessed neurocognitive or educational outcomes. Risk of bias was assessed using a modified Newcastle-Ottawa scale. We used random effects models and expressed the estimates as mean differences with 95% confidence intervals stratified by CKD stage.

RESULTS

Thirty-four studies (25 cross-sectional, n=2095; nine cohort, n=991) were included. The overall risk of bias was high because of selection and measurement biases. The global cognition (full-scale intelligence quotient) of children with CKD was classified as low average. Compared with the general population, the mean differences (95% confidence intervals) in full-scale intelligence quotient were -10.5 (95% confidence interval, -13.2 to -7.72; all CKD stages, n=758), -9.39 (95% confidence interval, -12.6 to -6.18; mild to moderate stage CKD, n=582), -16.2 (95% confidence interval, -33.2 to 0.86; dialysis, n=23), and -11.2 (95% confidence interval, -17.8 to -4.50; transplant, n=153). Direct comparisons showed that children with mild to moderate stage CKD and kidney transplants scored 11.2 (95% confidence interval, 2.98 to 19.4) and 10.1 (95% confidence interval, -1.81 to 22.0) full-scale intelligence quotient points higher than children on dialysis. Children with CKD also had lower scores than the general population in executive function and memory (verbal and visual) domains. Compared with children without CKD, the mean differences in academic skills (n=518) ranged from -15.7 to -1.22 for mathematics, from -9.04 to -0.17 for reading, and from -14.2 to 2.53 for spelling.

CONCLUSIONS

Children with CKD may have low-average cognition compared with the general population, with mild deficits observed across academic skills, executive function, and visual and verbal memory. Limited evidence suggests that children on dialysis may be at greatest risk compared with children with mild to moderate stage CKD and transplant recipients.

Weekly Standard Kt/Vurea and Clinical Outcomes in Home and In-Center Hemodialysis

BACKGROUND AND OBJECTIVES

Patients undergoing hemodialysis with a frequency other than thrice weekly are not included in current clinical performance metrics for dialysis adequacy. The weekly standard Kt/Vurea incorporates treatment frequency, but there are limited data on its association with clinical outcomes.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

We used multivariable regression to examine the association of dialysis standard Kt/Vurea with BP and metabolic control (serum potassium, calcium, bicarbonate, and phosphorus) in patients incidental to dialysis treated with home (n=2373) or in-center hemodialysis (n=109,273). We further used Cox survival models to examine the association of dialysis standard Kt/Vurea with mortality, hospitalization, and among patients on home hemodialysis, transfer to in-center hemodialysis.

RESULTS

After adjustment for potential confounders, patients with dialysis standard Kt/Vurea <2.1 had higher BPs compared with patients with standard Kt/Vurea 2.1 to <2.3 (3.4 mm Hg higher [P<0.001] for home hemodialysis and 0.9 mm Hg higher [P<0.001] for in-center hemodialysis). There were no clinically meaningful associations between dialysis standard Kt/Vurea and markers of metabolic control, irrespective of dialysis modality. There was no association between dialysis standard Kt/Vurea and risk for mortality, hospitalization, or transfer to in-center hemodialysis among patients undergoing home hemodialysis. Among patients on in-center hemodialysis, dialysis standard Kt/Vurea <2.1 was associated with higher risk (adjusted hazard ratio, 1.11; 95% confidence interval, 1.07 to 1.14) and standard Kt/Vurea ≥2.3 was associated with lower risk (adjusted hazard ratio, 0.97; 95% confidence interval, 0.94 to 0.99) for death compared with standard Kt/Vurea 2.1 to <2.3. Additional analyses limited to patients with available data on residual kidney function showed similar relationships of dialysis and total (dialysis plus kidney) standard Kt/Vurea with outcomes.

CONCLUSIONS

Current targets for standard Kt/Vurea have limited utility in identifying individuals at increased risk for adverse clinical outcomes for those undergoing home hemodialysis but may enhance risk stratification for in-center hemodialysis.

Person-Centered Integrated Care for Chronic Kidney Disease: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

BACKGROUND AND OBJECTIVES

The effectiveness of person-centered integrated care strategies for CKD is uncertain. We conducted a systematic review and meta-analysis of randomized, controlled trials to assess the effect of person-centered integrated care for CKD.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

We searched MEDLINE, Embase, and Cochrane Central Register of Controlled Trials (from inception to April of 2016), and selected randomized, controlled trials of person-centered integrated care interventions with a minimum follow-up of 3 months. Random-effects meta-analysis was used to assess the effect of person-centered integrated care.

RESULTS

We included 14 eligible studies covering 4693 participants with a mean follow-up of 12 months. In moderate quality evidence, person-centered integrated care probably had no effect on all-cause mortality (relative risk [RR], 0.86; 95% confidence interval [95% CI], 0.68 to 1.08) or health-related quality of life (standardized mean difference, 0.02; 95% CI, -0.05 to 0.10). The effects on renal replacement therapy (RRT) (RR, 1.00; 95% CI, 0.65 to 1.55), serum creatinine levels (mean difference, 0.59 mg/dl; 95% CI, -0.38 to 0.36), and eGFR (mean difference, 1.51 ml/min per 1.73 m2; 95% CI, -3.25 to 6.27) were very uncertain. Quantitative analysis suggested that person-centered integrated care interventions may reduce all-cause hospitalization (RR, 0.38; 95% CI, 0.15 to 0.95) and improve BP control (RR, 1.20; 95% CI, 1.00 to 1.44), although the certainty of the evidence was very low.

CONCLUSIONS

Person-centered integrated care may have little effect on mortality or quality of life. The effects on serum creatinine, eGFR, and RRT are uncertain, although person-centered integrated care may lead to fewer hospitalizations and improved BP control.

Nondepressive Psychosocial Factors and CKD Outcomes in Black Americans

BACKGROUND AND OBJECTIVES

Established risk factors for CKD do not fully account for risk of CKD in black Americans. We studied the association of nondepressive psychosocial factors with risk of CKD in the Jackson Heart Study.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

We used principal component analysis to identify underlying constructs from 12 psychosocial baseline variables (perceived daily, lifetime, and burden of lifetime discrimination; stress; anger in; anger out; hostility; pessimism; John Henryism; spirituality; perceived social status; and social support). Using multivariable models adjusted for demographics and comorbidity, we examined the association of psychosocial variables with baseline CKD prevalence, eGFR decline, and incident CKD during follow-up.

RESULTS

Of 3390 (64%) Jackson Heart Study participants with the required data, 656 (19%) had prevalent CKD. Those with CKD (versus no CKD) had lower perceived daily (mean [SD] score =7.6 [8.5] versus 9.7 [9.0]) and lifetime discrimination (2.5 [2.0] versus 3.1 [2.2]), lower perceived stress (4.2 [4.0] versus 5.2 [4.4]), higher hostility (12.1 [5.2] versus 11.5 [4.8]), higher John Henryism (30.0 [4.8] versus 29.7 [4.4]), and higher pessimism (2.3 [2.2] versus 2.0 [2.1]; all P<0.05). Principal component analysis identified three factors from the 12 psychosocial variables: factor 1, life stressors (perceived discrimination, stress); factor 2, moods (anger, hostility); and, factor 3, coping strategies (John Henryism, spirituality, social status, social support). After adjustments, factor 1 (life stressors) was negatively associated with prevalent CKD at baseline among women only: odds ratio, 0.76 (95% confidence interval, 0.65 to 0.89). After a median follow-up of 8 years, identified psychosocial factors were not significantly associated with eGFR decline (life stressors: β=0.08; 95% confidence interval, -0.02 to 0.17; moods: β=0.03; 95% confidence interval, -0.06 to 0.13; coping: β=-0.02; 95% confidence interval, -0.12 to 0.08) or incident CKD (life stressors: odds ratio, 1.07; 95% confidence interval, 0.88 to 1.29; moods: odds ratio, 1.02; 95% confidence interval, 0.84 to 1.24; coping: odds ratio, 0.91; 95% confidence interval, 0.75 to 1.11).

CONCLUSIONS

Greater life stressors were associated with lower prevalence of CKD at baseline in the Jackson Heart Study. However, psychosocial factors were not associated with risk of CKD over a median follow-up of 8 years.

PODCAST

This article contains a podcast at https://www.asn-online.org/media/podcast/CJASN/2018_01_03_CJASNPodcast_18_2_L.mp3.

Standardized Transplantation Referral Ratio to Assess Performance of Transplant Referral among Dialysis Facilities

BACKGROUND AND OBJECTIVES

For patients with ESRD, referral from a dialysis facility to a transplant center for evaluation is an important step toward kidney transplantation. However, a standardized measure for assessing clinical performance of dialysis facilities transplant access is lacking. We describe methodology for a new dialysis facility measure: the Standardized Transplantation Referral Ratio.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

Transplant referral data from 8308 patients with incident ESRD within 249 dialysis facilities in the United States state of Georgia were linked with US Renal Data System data from January of 2008 to December of 2011, with follow-up through December of 2012. Facility-level expected referrals were computed from a two-stage Cox proportional hazards model after patient case mix risk adjustment including demographics and comorbidities. The Standardized Transplantation Referral Ratio (95% confidence interval) was calculated as a ratio of observed to expected referrals. Measure validity and reliability were assessed.

RESULTS

Over 2008-2011, facility Standardized Transplantation Referral Ratios in Georgia ranged from 0 to 4.87 (mean =1.16, SD=0.76). Most (77%) facilities had observed referrals as expected, whereas 11% and 12% had Standardized Transplantation Referral Ratios significantly greater than and less than expected, respectively. Age, race, sex, and comorbid conditions were significantly associated with the likelihood of referral, and they were included in risk adjustment for Standardized Transplantation Referral Ratio calculations. The Standardized Transplantation Referral Ratios were positively associated with evaluation, waitlisting, and transplantation (r=0.46, 0.35, and 0.20, respectively; P<0.01). On average, approximately 33% of the variability in Standardized Transplantation Referral Ratios was attributed to between-facility variation, and 67% of the variability in Standardized Transplantation Referral Ratios was attributed to within-facility variation.

CONCLUSIONS

The majority of observed variation in dialysis facility referral performance was due to characteristics within a dialysis facility rather than patient factors included in risk adjustment models. Our study shows a method for computing a facility-level standardized measure for transplant referral on the basis of a pilot sample of Georgia dialysis facilities that could be used to monitor transplant referral performance of dialysis facilities.

A Discrete Choice Study of Patient Preferences for Dialysis Modalities

BACKGROUND AND OBJECTIVES

Improved knowledge about factors that influence patient choices when considering dialysis modality could facilitate health care interventions to increase rates of home dialysis. We aimed to quantify the attributes of dialysis care and the tradeoffs that patients consider when making decisions about dialysis modalities.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

We conducted a prospective, discrete choice experiment survey with random parameter logit analysis to quantify preferences and tradeoffs for attributes of dialysis treatment in 143 adult patients with CKD expected to require RRT within 12 months (predialysis). The attributes included schedule flexibility, patient out of pocket costs, subsidized transport services, level of nursing support, life expectancy, dialysis training time, wellbeing on dialysis, and dialysis schedule (frequency and duration). We reported outcomes using β-coefficients with corresponding odds ratios and 95% confidence intervals for choosing home-based dialysis (peritoneal dialysis or hemodialysis) compared with facility hemodialysis.

RESULTS

Home-based therapies were significantly preferred with the following attributes: longer survival (odds ratio per year, 1.63; 95% confidence interval, 1.25 to 2.12), increased treatment flexibility (odds ratio, 9.22; 95% confidence interval, 2.71 to 31.3), improved wellbeing (odds ratio, 210; 95% confidence interval, 15 to 2489), and more nursing support (odds ratio, 87.3; 95% confidence interval, 3.8 to 2014). Respondents were willing to accept additional out of pocket costs of approximately New Zealand $400 (United States $271) per month (95% confidence interval, New Zealand $333 to $465) to receive increased nursing support. Patients were willing to accept out of pocket costs of New Zealand $223 (United States $151) per month (95% confidence interval, New Zealand $195 to $251) for more treatment flexibility.

CONCLUSIONS

Patients preferred home dialysis over facility-based care when increased nursing support was available and when longer survival, wellbeing, and flexibility were expected. Sociodemographics, such as age, ethnicity, and income, influenced patient choice.

Predicting Outcome in Patients with Anti-GBM Glomerulonephritis

BACKGROUND AND OBJECTIVES

Large studies on long-term kidney outcome in patients with anti-glomerular basement membrane (anti-GBM) GN are lacking. This study aimed to identify clinical and histopathologic parameters that predict kidney outcome in these patients.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

This retrospective analysis included a total of 123 patients with anti-GBM GN between 1986 and 2015 from six centers worldwide. Their kidney biopsy samples were classified according to the histopathologic classification for ANCA-associated GN. Clinical data such as details of treatment were retrieved from clinical records. The primary outcome parameter was the occurrence of ESRD. Kidney survival was analyzed using the log-rank test and Cox regression analyses.

RESULTS

The 5-year kidney survival rate was 34%, with an improved rate observed among patients diagnosed after 2007 (P=0.01). In patients with anti-GBM GN, histopathologic class and kidney survival were associated (P<0.001). Only one of 15 patients with a focal class biopsy sample (≥50% normal glomeruli) developed ESRD. Patients with a sclerotic class biopsy sample (≥50% globally sclerotic glomeruli) and patients with 100% cellular crescents did not recover from dialysis dependency at presentation. In multivariable analysis, dialysis dependency at presentation (hazard ratio [HR], 3.17; 95% confidence interval [95% CI], 1.59 to 6.32), percentage of normal glomeruli (HR, 0.97; 95% CI, 0.95 to 0.99), and extent of interstitial infiltrate (HR, 2.02; 95% CI, 1.17 to 3.50) were predictors of ESRD during follow-up.

CONCLUSIONS

Dialysis dependency, low percentage of normal glomeruli, and large extent of interstitial infiltrate are associated with poor kidney outcome in anti-GBM GN. Kidney outcome has improved during recent years; the success rate doubled after 2007.

PODCAST

This article contains a podcast at https://www.asn-online.org/media/podcast/CJASN/2017_11_21_CJASNPodcast_18_1_v.mp3.