Associations of Kidney Functional Magnetic Resonance Imaging Biomarkers with Markers of Inflammation in Individuals with Chronic Kidney Disease

BACKGROUND

Greater fibrosis and decreased oxygenation may amplify systemic inflammation, but data on the associations of kidney functional magnetic resonance imaging (fMRI) measurements of fibrosis (apparent diffusion coefficient [ADC]) and oxygenation (relaxation rate [R2*]) with systemic markers of inflammation are limited.

METHODS

We evaluated associations of baseline kidney fMRI-derived ADC and R2* with baseline and follow-up serum interleukin-6 (IL-6) and C-reactive protein (CRP) in 127 participants from the COMBINE trial, a randomized, 12-month trial of nicotinamide and lanthanum carbonate vs. placebo in individuals with CKD stages 3-4. Cross-sectional analyses of baseline kidney fMRI biomarkers and markers of inflammation used multivariable linear regression. Longitudinal analyses of baseline kidney fMRI biomarkers and change in markers of inflammation over time used linear mixed effects models.

RESULTS

Mean±SD eGFR, ADC, and R2* were 32.2±8.7 ml/min/1.73m2, 1.46±0.17 x10-3 mm2/s, and 20.3±3.1 s-1, respectively. Median [IQR] IL-6 and CRP were 3.7 [2.4-4.9] pg/mL and 2.8 [1.2-6.3] mg/L. After multivariable adjustment, IL-6 and CRP were 13.1% and 27.3% higher per 1 SD decrease in baseline cortical ADC. Baseline cortical R2* did not have a significant association with IL-6 or CRP. Mean annual IL-6 and CRP slopes were 0.98 pg/mL per year and 0.91 mg/L per year, respectively. Baseline cortical ADC and R2* did not have significant associations with change in IL-6 or CRP over time.

CONCLUSIONS

Lower cortical ADC, suggestive of greater fibrosis, was associated with higher systemic inflammation. Baseline kidney fMRI biomarkers did not associate with changes in systemic markers of inflammation over time.

Arteriovenous Fistula Histology, Hemodynamics, and Wall Mechanics: A Case Report of Successful and Failed Access in a Single Patient

The low 1-year patency rate of mature arteriovenous fistulas (AVFs) remains a significant clinical problem. Although vessel properties and biomechanics have been suggested to affect AVF function, understanding their roles in AVF patency failure is challenging owing to the heterogeneity within the patient population, including demographics and comorbid conditions. In this study, we present a case of a patient with 2 upper-arm AVFs with different 1-year patency outcomes and investigate whether they had different histologic features before the AVF creation surgery and biomechanics at 1 day and 6 weeks after the AVF creation surgery using magnetic resonance imaging-based fluid structure interaction simulations. Despite both AVFs being in the upper arm, created <1 year apart by the same surgeon, and having similar preoperative vessel diameters, the 1-year patent AVF had less preoperative intimal collagen and higher wall shear stress 1 day after AVF creation, when compared with the AVF that failed by 1 year. Thus, a low intimal collagen content before the AVF surgery and higher wall shear stress immediately after the AVF creation surgery may be important for long-term AVF patency and should be investigated with larger cohorts.

Role of Age and Competing Risk of Death in the Racial Disparity of Kidney Failure Incidence after Onset of CKD

SIGNIFICANCE STATEMENT

Black adults in the United States have 2-4 times higher incidence of kidney failure than White adults. Yet, the reasons underlying this disparity remain poorly understood. Among 547,188 US veterans with new-onset CKD, according to a new race-free GFR equation, Black veterans had a 2.5-fold higher cumulative incidence of kidney failure, compared with White veterans, in any follow-up period from CKD onset. This disparity resulted from a combination of higher hazards of progression to kidney failure and lower hazards of competing-risk death in Black veterans. Both, in turn, were largely explained by the younger age at CKD onset in Black veterans, underscoring an urgent need to prevent early onset and slow progression of CKD in younger Black adults.

BACKGROUND

The Black adult population is well known to have higher incidence of kidney failure than their White counterpart in the United States, but the reasons underlying this disparity are unclear. We assessed the racial differences in kidney failure and death from onset of CKD on the basis of the race-free 2021 CKD Epidemiology Collaboration equation and examined the extent to which these differences could be explained by factors at the time of CKD onset.

METHODS

We analyzed a national cohort consisting of 547,188 US veterans (103,821 non-Hispanic Black and 443,367 non-Hispanic White), aged 18-85 years, with new-onset CKD between 2005 and 2016 who were followed through 10 years or May 2018 for incident kidney failure with replacement therapy (KFRT) and pre-KFRT death.

RESULTS

At CKD onset, Black veterans were, on average, 7.8 years younger than White veterans. In any time period from CKD onset, the cumulative incidence of KFRT was 2.5-fold higher for Black versus White veterans. Meanwhile, Black veterans had persistently >2-fold higher hazards of KFRT throughout follow-up (overall hazard ratio [95% confidence interval], 2.38 [2.31 to 2.45]) and conversely had 17%-48% decreased hazards of pre-KFRT death. These differences were reduced after accounting for the racial difference in age at CKD onset.

CONCLUSIONS

The 2.5-fold higher cumulative incidence of kidney failure in Black adults resulted from a combination of higher hazards of progression to kidney failure and lower hazards of the competing risk of death, both of which can be largely explained by the younger age at CKD onset in Black compared with White adults.

Role of Diuretics in Cardiovascular Events and Mortality in Systolic Blood Pressure Intervention Trial: A Post Hoc Analysis

BACKGROUND

In a post hoc analysis, we examined whether postrandomization diuretics use can explain and/or mediate the beneficial effects of intensive systolic BP lowering on cardiovascular disease and all-cause mortality in the Systolic Blood Pressure Intervention Trial (SPRINT).

METHODS

SPRINT was a randomized, controlled trial of 9361 participants comparing the effects of intensive (systolic BP target <120 mm Hg) versus standard (systolic BP target <140 mm Hg) BP control on a primary composite cardiovascular end point in participants aged 50 years or older with systolic BP of 130-180 mm Hg. In time-varying multivariable Cox analyses, we assessed hazard ratios (HRs) of cardiovascular end points and all-cause mortality in participants on thiazide type, loop and/or potassium (K) sparing, or no diuretics. We also conducted mediation analysis to formally assess the role of diuretics in the effects of intensive systolic BP lowering.

RESULTS

At baseline, diuretics were prescribed in 46% and 48% of participants in standard and intensive systolic BP-lowering groups, respectively, and in 46% and 74% in the corresponding groups during the trial. The lower risk of cardiovascular end points in the intensive group (HR, 0.75; 95% confidence interval [CI], 0.64 to 0.89) persisted after adjustment for postrandomization time-varying diuretics use (HR, 0.74; 95% CI, 0.62 to 0.89). Across the entire study population, time-varying diuretics use was not associated with cardiovascular end points (compared with no diuretics, HR for thiazide type, 0.89; 95% CI, 0.73 to 1.10, and loop/K sparing, 1.29; 95% CI, 0.97 to 1.73). However, thiazide-type diuretics were associated with lower risk of cardiovascular end points in the intensive (HR, 0.62; 95% CI, 0.46 to 0.85) but not in the standard (HR, 1.07; 95% CI, 0.82 to 1.39) group. In mediation analysis, HRs for total effect, direct effect (not mediated through diuretics use), and indirect effect (mediated through diuretics) of the intervention on cardiovascular end points were 0.66 (95% CI, 0.54 to 0.79), 0.67 (95% CI, 0.54 to 0.81), and 0.98 (95% CI, 0.88 to 1.10), respectively. The results were largely similar for all-cause mortality.

CONCLUSIONS

The favorable effects of intensive systolic BP lowering on cardiovascular end points and all-cause mortality in SPRINT were independent of and not mediated by time-varying diuretics use. However, thiazide-type diuretics use associated with benefit if intensive systolic BP lowering was targeted.

Oral Sodium Bicarbonate and Bone Turnover in CKD: A Secondary Analysis of the BASE Pilot Trial

SIGNIFICANCE STATEMENT

In CKD, metabolic acidosis is commonly treated with alkali in the hope that it will improve bone health. In a post hoc analysis of the Bicarbonate Administration to Stabilize eGFR Pilot Trial, we investigated whether sodium bicarbonate affects serum levels of bone turnover markers and other hormones related to bone health in individuals with CKD who have normal to slightly reduced total CO2 (20-28 mEq/L). Sodium bicarbonate increased serum levels of α-klotho but had no significant effect on other bone health markers, including intact fibroblast growth factor-23 (iFGF-23), intact parathyroid hormone (iPTH), and bone-specific alkaline phosphatase (B-SAP). Further study is needed to determine the effect of bicarbonate administration on clinical aspects of bone health.

BACKGROUND

Treatment with alkali has been hypothesized to improve bone health in CKD by mitigating adverse effects of acid on bone mineral. We investigated the effect of treatment with sodium bicarbonate on bone turnover markers and other factors related to bone metabolism in CKD.

METHODS

This is a post hoc analysis of the Bicarbonate Administration to Stabilize eGFR Pilot Trial in which 194 individuals with CKD and serum total CO2 20-28 mEq/L were randomly assigned to placebo or one of two doses of sodium bicarbonate (0.5 or 0.8 mEq/kg lean body weight per day) for 28 weeks. The following serum measurements were performed at baseline, week 12, and week 28: B-SAP, c-telopeptide, procollagen type I intact N-terminal propeptide, iPTH, iFGF-23, soluble klotho, 25-hydroxyvitamin D, 1,25-dihydroxyvitamin D, and tartrate-resistant acid phosphatase 5b. The difference (sodium bicarbonate versus placebo) in mean change of each bone biomarker from baseline was determined using linear mixed models.

RESULTS

One hundred sixty-eight participants submitted samples for post hoc investigations. Mean eGFR was 37±10 ml/min per 1.73 m2 and mean total CO2 was 24±3 mEq/L at baseline. Sodium bicarbonate induced a dose-dependent increase in soluble klotho levels compared with placebo. There was no significant effect of treatment with either dose of sodium bicarbonate on any of the other bone biomarkers, including iFGF-23, iPTH, and B-SAP. Effects on bone biomarkers were similar in those with baseline serum total CO2 <24 mEq/L compared with those with total CO2 ≥24 mEq/L.

CONCLUSIONS

In this pilot trial of individuals with CKD and total CO2 20-28 mEq/L, sodium bicarbonate treatment increased serum klotho levels but did not affect other bone health markers over 28 weeks.

CLINICAL TRIAL REGISTRY NAME AND REGISTRATION NUMBER

ClinicalTrials.gov, NCT02521181.

Effects of empagliflozin on progression of chronic kidney disease: a prespecified secondary analysis from the empa-kidney trial

BACKGROUND

Sodium-glucose co-transporter-2 (SGLT2) inhibitors reduce progression of chronic kidney disease and the risk of cardiovascular morbidity and mortality in a wide range of patients. However, their effects on kidney disease progression in some patients with chronic kidney disease are unclear because few clinical kidney outcomes occurred among such patients in the completed trials. In particular, some guidelines stratify their level of recommendation about who should be treated with SGLT2 inhibitors based on diabetes status and albuminuria. We aimed to assess the effects of empagliflozin on progression of chronic kidney disease both overall and among specific types of participants in the EMPA-KIDNEY trial.

METHODS

EMPA-KIDNEY, a randomised, controlled, phase 3 trial, was conducted at 241 centres in eight countries (Canada, China, Germany, Italy, Japan, Malaysia, the UK, and the USA), and included individuals aged 18 years or older with an estimated glomerular filtration rate (eGFR) of 20 to less than 45 mL/min per 1·73 m2, or with an eGFR of 45 to less than 90 mL/min per 1·73 m2 with a urinary albumin-to-creatinine ratio (uACR) of 200 mg/g or higher. We explored the effects of 10 mg oral empagliflozin once daily versus placebo on the annualised rate of change in estimated glomerular filtration rate (eGFR slope), a tertiary outcome. We studied the acute slope (from randomisation to 2 months) and chronic slope (from 2 months onwards) separately, using shared parameter models to estimate the latter. Analyses were done in all randomly assigned participants by intention to treat. EMPA-KIDNEY is registered at ClinicalTrials.gov, NCT03594110.

FINDINGS

Between May 15, 2019, and April 16, 2021, 6609 participants were randomly assigned and then followed up for a median of 2·0 years (IQR 1·5-2·4). Prespecified subgroups of eGFR included 2282 (34·5%) participants with an eGFR of less than 30 mL/min per 1·73 m2, 2928 (44·3%) with an eGFR of 30 to less than 45 mL/min per 1·73 m2, and 1399 (21·2%) with an eGFR 45 mL/min per 1·73 m2 or higher. Prespecified subgroups of uACR included 1328 (20·1%) with a uACR of less than 30 mg/g, 1864 (28·2%) with a uACR of 30 to 300 mg/g, and 3417 (51·7%) with a uACR of more than 300 mg/g. Overall, allocation to empagliflozin caused an acute 2·12 mL/min per 1·73 m2 (95% CI 1·83-2·41) reduction in eGFR, equivalent to a 6% (5-6) dip in the first 2 months. After this, it halved the chronic slope from -2·75 to -1·37 mL/min per 1·73 m2 per year (relative difference 50%, 95% CI 42-58). The absolute and relative benefits of empagliflozin on the magnitude of the chronic slope varied significantly depending on diabetes status and baseline levels of eGFR and uACR. In particular, the absolute difference in chronic slopes was lower in patients with lower baseline uACR, but because this group progressed more slowly than those with higher uACR, this translated to a larger relative difference in chronic slopes in this group (86% [36-136] reduction in the chronic slope among those with baseline uACR <30 mg/g compared with a 29% [19-38] reduction for those with baseline uACR ≥2000 mg/g; ptrend<0·0001).

INTERPRETATION

Empagliflozin slowed the rate of progression of chronic kidney disease among all types of participant in the EMPA-KIDNEY trial, including those with little albuminuria. Albuminuria alone should not be used to determine whether to treat with an SGLT2 inhibitor.

FUNDING

Boehringer Ingelheim and Eli Lilly.

Impact of primary kidney disease on the effects of empagliflozin in patients with chronic kidney disease: secondary analyses of the EMPA-KIDNEY trial

BACKGROUND

The EMPA-KIDNEY trial showed that empagliflozin reduced the risk of the primary composite outcome of kidney disease progression or cardiovascular death in patients with chronic kidney disease mainly through slowing progression. We aimed to assess how effects of empagliflozin might differ by primary kidney disease across its broad population.

METHODS

EMPA-KIDNEY, a randomised, controlled, phase 3 trial, was conducted at 241 centres in eight countries (Canada, China, Germany, Italy, Japan, Malaysia, the UK, and the USA). Patients were eligible if their estimated glomerular filtration rate (eGFR) was 20 to less than 45 mL/min per 1·73 m2, or 45 to less than 90 mL/min per 1·73 m2 with a urinary albumin-to-creatinine ratio (uACR) of 200 mg/g or higher at screening. They were randomly assigned (1:1) to 10 mg oral empagliflozin once daily or matching placebo. Effects on kidney disease progression (defined as a sustained ≥40% eGFR decline from randomisation, end-stage kidney disease, a sustained eGFR below 10 mL/min per 1·73 m2, or death from kidney failure) were assessed using prespecified Cox models, and eGFR slope analyses used shared parameter models. Subgroup comparisons were performed by including relevant interaction terms in models. EMPA-KIDNEY is registered with ClinicalTrials.gov, NCT03594110.

FINDINGS

Between May 15, 2019, and April 16, 2021, 6609 participants were randomly assigned and followed up for a median of 2·0 years (IQR 1·5-2·4). Prespecified subgroupings by primary kidney disease included 2057 (31·1%) participants with diabetic kidney disease, 1669 (25·3%) with glomerular disease, 1445 (21·9%) with hypertensive or renovascular disease, and 1438 (21·8%) with other or unknown causes. Kidney disease progression occurred in 384 (11·6%) of 3304 patients in the empagliflozin group and 504 (15·2%) of 3305 patients in the placebo group (hazard ratio 0·71 [95% CI 0·62-0·81]), with no evidence that the relative effect size varied significantly by primary kidney disease (pheterogeneity=0·62). The between-group difference in chronic eGFR slopes (ie, from 2 months to final follow-up) was 1·37 mL/min per 1·73 m2 per year (95% CI 1·16-1·59), representing a 50% (42-58) reduction in the rate of chronic eGFR decline. This relative effect of empagliflozin on chronic eGFR slope was similar in analyses by different primary kidney diseases, including in explorations by type of glomerular disease and diabetes (p values for heterogeneity all >0·1).

INTERPRETATION

In a broad range of patients with chronic kidney disease at risk of progression, including a wide range of non-diabetic causes of chronic kidney disease, empagliflozin reduced risk of kidney disease progression. Relative effect sizes were broadly similar irrespective of the cause of primary kidney disease, suggesting that SGLT2 inhibitors should be part of a standard of care to minimise risk of kidney failure in chronic kidney disease.

FUNDING

Boehringer Ingelheim, Eli Lilly, and UK Medical Research Council.

Role of Anemia in Dementia Risk Among Veterans With Incident CKD

RATIONALE & OBJECTIVE

Although some evidence exists of increased dementia risk from anemia, it is unclear whether this association persists among adults with CKD. Anemia may be a key marker for dementia among adults with CKD, so we evaluated whether anemia is associated with an increased risk of dementia among adults with CKD.

STUDY DESIGN

Retrospective cohort study.

SETTING & PARTICIPANTS

The study included 620,095 veterans aged≥45 years with incident stage 3 CKD (estimated glomerular filtration rate [eGFR]<60mL/min/1.73m2) between January 2005 and December 2016 in the US Veterans Health Administration system and followed through December 31, 2018, for incident dementia, kidney failure, or death.

EXPOSURE

Anemia was assessed based on the average of hemoglobin levels (g/L) during the 2 years before the date of incident CKD and categorized as normal, mild, or moderate/severe anemia (≥12.0, 11.0-11.9,<11.0g/dL, respectively, for women, and≥13.0, 11.0-12.9,<11.0g/dL for men).

OUTCOME

Dementia and the composite outcome of kidney failure or death.

ANALYTICAL APPROACH

Adjusted cause-specific hazard ratios were estimated for each outcome.

RESULTS

At the time of incident CKD, the mean age of the participants was 72 years, 97% were male, and their mean eGFR was 51mL/min per 1.73m2. Over a median 4.1 years of follow-up, 92,306 veterans (15%) developed dementia before kidney failure or death. Compared with the veterans with CKD without anemia, the multivariable-adjusted models showed a 16% (95% CI, 14%-17%) significantly higher risk of dementia for those with mild anemia and a 27% (95% CI, 23%-31%) higher risk with moderate/severe anemia. Combined risk of kidney failure or death was higher at 39% (95% CI, 37%-40%) and 115% (95% CI, 112%-119%) for mild and moderate/severe anemia, respectively, compared with no anemia.

LIMITATIONS

Residual confounding from the observational study design. Findings may not be generalizable to the broader US population.

CONCLUSIONS

Anemia was significantly associated with an increased risk of dementia among veterans with incident CKD, underscoring the role of anemia as a predictor of dementia risk.

PLAIN-LANGUAGE SUMMARY

Adults with chronic kidney disease (CKD) often have anemia. Prior studies among adults in the general population suggest anemia is a risk factor for dementia, though it is unclear whether this association persists among adults with CKD. In this large study of veterans in the United States, we studied the association between anemia and the risk of 2 important outcomes in this population: (1) dementia and (2) kidney failure or death. We found that anemia was associated with a greater risk of dementia as well as risk of kidney failure or death. The study findings therefore emphasize the role of anemia as a key predictor of dementia risk among adults with CKD.

Identifying Patients for Intensive Blood Pressure Treatment Based on Cognitive Benefit: A Secondary Analysis of the SPRINT Randomized Clinical Trial

Importance

Intensive vs standard treatment to lower systolic blood pressure (SBP) reduces risk of mild cognitive impairment (MCI) or dementia; however, the magnitude of cognitive benefit likely varies among patients.

Objective

To estimate the magnitude of cognitive benefit of intensive vs standard systolic BP (SBP) treatment.

Design, Setting, and Participants

In this ad hoc secondary analysis of the Systolic Blood Pressure Intervention Trial (SPRINT), 9361 randomized clinical trial participants 50 years or older with high cardiovascular risk but without a history of diabetes, stroke, or dementia were followed up. The SPRINT trial was conducted between November 1, 2010, and August 31, 2016, and the present analysis was completed on October 31, 2022.

Intervention

Systolic blood pressure treatment to an intensive (<120 mm Hg) vs standard (<140 mm Hg) target.

Main Outcomes and Measures

The primary outcome was a composite of adjudicated probable dementia or amnestic MCI.

Results

A total of 7918 SPRINT participants were included in the analysis; 3989 were in the intensive treatment group (mean [SD] age, 67.9 [9.2] years; 2570 [64.4%] men; 1212 [30.4%] non-Hispanic Black) and 3929 were in the standard treatment group (mean [SD] age, 67.9 [9.4] years; 2570 [65.4%] men; 1249 [31.8%] non-Hispanic Black). Over a median follow-up of 4.13 (IQR, 3.50-5.88) years, there were 765 and 828 primary outcome events in the intensive treatment group and standard treatment group, respectively. Older age (hazard ratio [HR] per 1 SD, 1.87 [95% CI, 1.78-1.96]), Medicare enrollment (HR per 1 SD, 1.42 [95% CI, 1.35-1.49]), and higher baseline serum creatinine level (HR per 1 SD, 1.24 [95% CI, 1.19-1.29]) were associated with higher risk of the primary outcome, while better baseline cognitive functioning (HR per 1 SD, 0.43 [95% CI, 0.41-0.44]) and active employment status (HR per 1 SD, 0.44 [95% CI, 0.42-0.46]) were associated with lower risk of the primary outcome. Risk of the primary outcome by treatment goal was estimated accurately based on similar projected and observed absolute risk differences (C statistic = 0.79). Higher baseline risk for the primary outcome was associated with greater benefit (ie, larger absolute reduction of probable dementia or amnestic MCI) of intensive vs standard treatment across the full range of estimated baseline risk.

Conclusions and Relevance

In this secondary analysis of the SPRINT trial, participants with higher baseline projected risk of probable dementia or amnestic MCI gained greater absolute cognitive benefit from intensive vs standard SBP treatment in a monotonic fashion.

Trial Registration

ClinicalTrials.gov Identifier: NCT01206062.

Empagliflozin in Patients with Chronic Kidney Disease

BACKGROUND

The effects of empagliflozin in patients with chronic kidney disease who are at risk for disease progression are not well understood. The EMPA-KIDNEY trial was designed to assess the effects of treatment with empagliflozin in a broad range of such patients.

METHODS

We enrolled patients with chronic kidney disease who had an estimated glomerular filtration rate (eGFR) of at least 20 but less than 45 ml per minute per 1.73 m² of body-surface area, or who had an eGFR of at least 45 but less than 90 ml per minute per 1.73 m² with a urinary albumin-to-creatinine ratio (with albumin measured in milligrams and creatinine measured in grams) of at least 200. Patients were randomly assigned to receive empagliflozin (10 mg once daily) or matching placebo. The primary outcome was a composite of progression of kidney disease (defined as end-stage kidney disease, a sustained decrease in eGFR to <10 ml per minute per 1.73 m², a sustained decrease in eGFR of ≥40% from baseline, or death from renal causes) or death from cardiovascular causes.

RESULTS

A total of 6609 patients underwent randomization. During a median of 2.0 years of follow-up, progression of kidney disease or death from cardiovascular causes occurred in 432 of 3304 patients (13.1%) in the empagliflozin group and in 558 of 3305 patients (16.9%) in the placebo group (hazard ratio, 0.72; 95% confidence interval [CI], 0.64 to 0.82; P<0.001). Results were consistent among patients with or without diabetes and across subgroups defined according to eGFR ranges. The rate of hospitalization from any cause was lower in the empagliflozin group than in the placebo group (hazard ratio, 0.86; 95% CI, 0.78 to 0.95; P = 0.003), but there were no significant between-group differences with respect to the composite outcome of hospitalization for heart failure or death from cardiovascular causes (which occurred in 4.0% in the empagliflozin group and 4.6% in the placebo group) or death from any cause (in 4.5% and 5.1%, respectively). The rates of serious adverse events were similar in the two groups.

CONCLUSIONS

Among a wide range of patients with chronic kidney disease who were at risk for disease progression, empagliflozin therapy led to a lower risk of progression of kidney disease or death from cardiovascular causes than placebo. (Funded by Boehringer Ingelheim and others; EMPA-KIDNEY ClinicalTrials.gov number, NCT03594110; EudraCT number, 2017-002971-24.).

Association of Shear Stress with Subsequent Lumen Remodeling in Hemodialysis Arteriovenous Fistulas

BACKGROUND

Blood flow-induced wall shear stress is a strong local regulator of vascular remodeling, but its effects on arteriovenous fistula (AVF) remodeling are unclear.

METHODS

In this prospective cohort study, we used computational fluid dynamics simulations and statistical mixed-effects modeling to investigate the associations between wall shear stress and AVF remodeling in 120 participants undergoing AVF creation surgery. Postoperative magnetic resonance imaging data at 1 day, 6 weeks, and 6 months were used to derive current wall shear stress by computational fluid dynamic simulations and to quantify subsequent changes in AVF lumen cross-sectional area at 1-mm intervals along the proximal artery and AVF vein.

RESULTS

Combining artery and vein data, prior mean wall shear stress was significantly associated with lumen area expansion. Mean wall shear stress at day 1 was significantly associated with change in lumen area from day 1 to week 6 (11% larger area per interquartile range [IQR] higher mean wall shear stress, 95% confidence interval [95% CI], 5% to 18%; n =101), and mean wall shear stress at 6 weeks was significantly associated with change in lumen area from 6 weeks to month 6 (14% larger area per IQR higher, 95% CI, 3% to 28%; n =52). The association of mean wall shear stress at day 1 with lumen area expansion from day 1 to week 6 differed significantly by diabetes ( P =0.009): 27% (95% CI, 17% to 37%) larger area per IQR higher mean wall shear stress without diabetes and 9% (95% CI, -1% to 19%) with diabetes. Oscillatory shear index at day 1 was significantly associated with change in lumen area from day 1 to week 6 (5% smaller area per IQR higher oscillatory shear index, 95% CI, 3% to 7%), and oscillatory shear index at 6 weeks was significantly associated with change in lumen from 6 weeks to month 6 (7% smaller area per IQR higher oscillatory shear index, 95% CI, 2% to 11%). Wall shear stress spatial gradient was not significantly associated with subsequent remodeling. In a joint model, wall shear stress and oscillatory shear index statistically significantly interacted in their associations with lumen area expansion in a complex nonlinear fashion.

CONCLUSIONS

Higher wall shear stress and lower oscillatory shear index were associated with greater lumen expansion after AVF creation surgery.

Differential hemodynamics between arteriovenous fistulas with or without intervention before successful use

A significant number of arteriovenous fistulas (AVFs) fail to maturate for dialysis. Although interventions promote maturation, functional primary patency loss is higher for AVFs with interventions (assisted maturation) than AVFs without interventions (un-assisted maturation). Although blood flow-associated hemodynamics have long been proposed to affect AVF remodeling, the optimal hemodynamic parameters for un-assisted maturation are unclear. Additionally, AVF maturation progress is generally not investigated until 6 weeks after AVF creation, and the examination is focused on the AVF's venous limb. In this exploratory study, patients (n = 6) underwent magnetic resonance imaging (MRI) at 1 day, 6 weeks, and 6 months after AVF creation surgery. Before successful use for hemodialysis, three AVFs required intervention and three did not. MRI of the AVFs were used to calculate lumen cross-sectional area (CSA) and perform computational fluid dynamics (CFD) to analyze hemodynamics, including velocity, wall shear stress (WSS), and vorticity. For the venous limb, the no-intervention group and intervention group had similar pre-surgery vein diameter and 1-day post-surgery venous CSA. However, the no-intervention group had statistically larger 1-day venous velocity (0.97 ± 0.67 m/s; mean ± SD), WSS (333 ± 336 dyne/cm2) and vorticity (1709 ± 1290 1/s) than the intervention group (velocity = 0.23 ± 0.10 m/s; WSS = 49 ± 40 dyne/cm2; vorticity = 493.1 ± 227 1/s) (P < 0.05). At 6 months, the no-intervention group had statistically larger venous CSA (43.5 ± 27.4 mm2) than the intervention group (15.1 ± 6.2 mm2) (P < 0.05). Regarding the arterial limb, no-intervention AVF arteries also had statistically larger 1-day velocity (1.17 ± 1.0 m/s), WSS (340 ± 423 dyne/cm2), vorticity (1787 ± 1694 1/s), and 6-month CSA (22.6 ± 22.7 mm2) than the intervention group (velocity = 0.64 ± 0.36 m/s; WSS = 104 ± 116 dyne/cm2, P < 0.05; vorticity = 867 ± 4551/s; CSA = 10.7 ± 6.0 mm2, P < 0.05). Larger venous velocity, WSS, and vorticity immediately after AVF creation surgery may be important for later lumen enlargement and AVF maturation, with the potential to be used as a tool to help diagnose poor AVF maturation earlier. However, future studies using a larger cohort are needed to validate this finding and determine cut off values, if any.

Longer-Term All-Cause and Cardiovascular Mortality With Intensive Blood Pressure Control: A Secondary Analysis of a Randomized Clinical Trial

Importance

The Systolic Blood Pressure Intervention Trial (SPRINT) showed that intensive blood pressure control reduced cardiovascular morbidity and mortality. However, the legacy effect of intensive treatment is unknown.

Objective

To evaluate the long-term effects of randomization to intensive treatment with the incidence of cardiovascular and all-cause mortality approximately 4.5 years after the trial ended.

Design, Setting, and Participants

In this secondary analysis of a multicenter randomized clinical trial, randomization began on November 8, 2010, the trial intervention ended on August 20, 2015, and trial close-out visits occurred through July 2016. Patients 50 years and older with hypertension and increased cardiovascular risk but without diabetes or history of stroke were included from 102 clinic sites in the US and Puerto Rico. Analyses were conducted between October 2021 and February 2022.

Interventions

Randomization to systolic blood pressure (SBP) goal of less than 120 mm Hg (intensive treatment group; n = 4678) vs less than 140 mm Hg (standard treatment group; n = 4683).

Main Outcomes and Measures

Extended observational follow-up for mortality via the US National Death Index from 2016 through 2020. In a subset of 2944 trial participants, outpatient SBP from electronic health records during and after the trial were examined.

Results

Among 9361 randomized participants, the mean (SD) age was 67.9 (9.4) years, and 3332 (35.6%) were women. Over a median (IQR) intervention period of 3.3 (2.9-3.9) years, intensive treatment was beneficial for both cardiovascular mortality (hazard ratio [HR], 0.66; 95% CI, 0.49-0.89) and all-cause mortality (HR, 0.83; 95% CI, 0.68-1.01). However, at the median (IQR) total follow-up of 8.8 (8.3-9.3) years, there was no longer evidence of benefit for cardiovascular mortality (HR, 1.02; 95% CI, 0.84-1.24) or all-cause mortality (HR, 1.08; 95% CI, 0.94-1.23). In a subgroup of participants, the estimated mean outpatient SBP among participants randomized to intensive treatment increased from 132.8 mm Hg (95% CI, 132.0-133.7) at 5 years to 140.4 mm Hg (95% CI, 137.8-143.0) at 10 years following randomization.

Conclusions and Relevance

The beneficial effect of intensive treatment on cardiovascular and all-cause mortality did not persist after the trial. Given increasing outpatient SBP levels in participants randomized to intensive treatment following the trial, these results highlight the importance of consistent long-term management of hypertension.

Trial Registration

ClinicalTrials.gov Identifier: NCT01206062.

Age-Related Association between Multimorbidity and Mortality in US Veterans with Incident Chronic Kidney Disease

INTRODUCTION

Mortality is an important long-term indicator of the public health impact of chronic kidney disease (CKD). We investigated the role of individual comorbidities and multimorbidity on age-specific mortality risk among US veterans with new-onset CKD.

METHODS

The cohort included 892,005 veterans aged ≥18 years with incident CKD stage 3 between January 2004 and April 2018 in the US Veterans Health Administration (VHA) system and followed until death, December 2018, or up to 10 years. Incident CKD was defined as the first-time estimated glomerular filtration rate (eGFR) was <60 mL/min/1.73 m2 for >3 months. Comorbidities were ascertained using inpatient and outpatient clinical records in the VHA system and Medicare claims. We estimated death rates for any cardiovascular disease (CVD, a composite of 6 CVD conditions) and 15 non-CVD comorbidities, and adjusted risks of death (hazard ratio [HR], 95% confidence interval [CI]) overall and by age group at CKD incidence.

RESULTS

At CKD incidence, the mean age was 72 years, and 97% were male; the mean eGFR was 52 mL/min/1.73 m2, and 95% had ≥2 comorbidities (median, 4) in addition to CKD. During a median follow-up of 4.5 years, among the 16 comorbidities, CVD was associated with the highest relative risk of death in younger veterans (HR 1.96 [95% CI: 1.61-2.37] in ages 18-44 years and HR 1.66 [1.63-1.70] in ages 45-64 years). Dementia was associated with the highest relative risk of death among older veterans (HR 1.71 [1.68-1.74] in ages 65-84 years and HR 1.69 [1.65-1.73] in ages 85-100 years). The additive effect of multimorbidity on risk of death was stronger in younger than older veterans. Compared to having 1 or no comorbidity at CKD onset, the risk of death with ≥5 comorbidities was >7-fold higher among veterans aged 18-44 years and >2-fold higher among veterans aged 85-100 years.

CONCLUSION

The large burden of comorbidities in US veterans with newly identified CKD places them at the risk of premature death. Compared with older veterans, younger veterans with multiple comorbidities, particularly with CVD, at CKD onset are at an even higher relative risk of death.

Markers of Kidney Tubular Secretion and Risk of Adverse Events in SPRINT Participants with CKD

BACKGROUND

Kidney tubular secretion is an essential mechanism for clearing many common antihypertensive drugs and other metabolites and toxins. It is unknown whether novel measures of tubular secretion are associated with adverse events (AEs) during hypertension treatment.

METHODS

Among 2089 SPRINT (Systolic Blood Pressure Intervention Trial) participants with baseline eGFR <60 ml/min per 1.73 m2, we created a summary secretion score by averaging across the standardized spot urine-to-plasma ratios of ten novel endogenous tubular secretion measures, with lower urine-to-plasma ratios reflecting worse tubular secretion. Multivariable Cox proportional hazards models were used to evaluate associations between the secretion score and risk of a composite of prespecified serious AEs (hypotension, syncope, bradycardia, AKI, electrolyte abnormalities, and injurious falls). The follow-up protocol for SPRINT routinely assessed two laboratory monitoring AEs (hyperkalemia and hypokalemia).

RESULTS

Overall, 30% of participants experienced at least one AE during a median follow-up of 3.0 years. In multivariable models adjusted for eGFR and albuminuria, lower (worse) secretion scores at baseline were associated with greater risk of the composite AE outcome (hazard ratio per 1-SD lower secretion score, 1.16; 95% confidence interval, 1.04 to 1.27). In analyses of the individual AEs, lower secretion score was associated with significantly greater risk of AKI, serious electrolyte abnormalities, and ambulatory hyperkalemia. Associations were similar across randomized treatment assignment groups.

CONCLUSION

Among SPRINT participants with CKD, worse tubular secretion was associated with greater risk of AEs, independent of eGFR and albuminuria.

Kidney tubule health, mineral metabolism and adverse events in persons with CKD in SPRINT

BACKGROUND

Measures of kidney tubule health are risk markers for acute kidney injury (AKI) in persons with chronic kidney disease (CKD) during hypertension treatment, but their associations with other adverse events (AEs) are unknown.

METHODS

Among 2377 Systolic Blood Pressure Intervention Trial (SPRINT) participants with CKD, we measured at baseline eight urine biomarkers of kidney tubule health and two serum biomarkers of mineral metabolism pathways that act on the kidney tubules. Cox proportional hazards models were used to evaluate biomarker associations with risk of a composite of pre-specified serious AEs (hypotension, syncope, electrolyte abnormalities, AKI, bradycardia and injurious falls) and outpatient AEs (hyperkalemia and hypokalemia).

RESULTS

At baseline, the mean age was 73 ± 9 years and mean estimated glomerular filtration rate (eGFR) was 46 ± 11 mL/min/1.73 m2. During a median follow-up of 3.8 years, 716 (30%) participants experienced the composite AE. Higher urine interleukin-18, kidney injury molecule-1, neutrophil gelatinase-associated lipocalin (NGAL) and monocyte chemoattractant protein-1 (MCP-1), lower urine uromodulin (UMOD) and higher serum fibroblast growth factor-23 were individually associated with higher risk of the composite AE outcome in multivariable-adjusted models including eGFR and albuminuria. When modeling biomarkers in combination, higher NGAL [hazard ratio (HR) = 1.08 per 2-fold higher biomarker level, 95% confidence interval (CI) 1.03-1.13], higher MCP-1 (HR = 1.11, 95% CI 1.03-1.19) and lower UMOD (HR = 0.91, 95% CI 0.85-0.97) were each associated with higher composite AE risk. Biomarker associations did not vary by intervention arm (P > 0.10 for all interactions).

CONCLUSIONS

Among persons with CKD, several kidney tubule biomarkers are associated with higher risk of AEs during hypertension treatment, independent of eGFR and albuminuria.

Plasma amyloid beta, neurofilament light chain, and total tau in the Systolic Blood Pressure Intervention Trial (SPRINT)

INTRODUCTION

Lowering blood pressure (BP) reduces the risk for cognitive impairment and the progression of cerebral white matter lesions. It is unclear whether hypertension control also influences plasma biomarkers related to Alzheimer's disease and non-disease-specific neurodegeneration.

METHODS

We examined the effect of intensive (< 120 mm Hg) versus standard (< 140 mm Hg) BP control on longitudinal changes in plasma amyloid beta (Aβ)40 and Aβ42 , total tau, and neurofilament light chain (NfL) in a subgroup of participants from the Systolic Blood Pressure Intervention Trial (N = 517).

RESULTS

Over 3.8 years, there were no significant between-group differences for Aβ40, Aβ42, Aβ42 /Aβ40, or total tau. Intensive treatment was associated with larger increases in NfL compared to standard treatment. Adjusting for kidney function, but not BP, attenuated the association between intensive treatment and NfL.

DISCUSSION

Intensive BP treatment was associated with changes in NfL, which were correlated with changes in kidney function associated with intensive treatment.

TRIAL REGISTRATION

clinicaltrials.gov Identifier: NCT01206062.

Risk of Mild Cognitive Impairment or Probable Dementia in New Users of Angiotensin II Receptor Blockers and Angiotensin-Converting Enzyme Inhibitors: A Secondary Analysis of Data From the Systolic Blood Pressure Intervention Trial (SPRINT)

Importance

The cardiovascular and renal outcomes of angiotensin-II receptor blocker (ARB) and angiotensin-converting enzyme inhibitor (ACEI) treatment are well-known; however, few studies have evaluated initiation of these agents and cognitive impairment.

Objective

To emulate a target trial to evaluate the cognitive outcomes of initiating an ARB- vs ACEI-based antihypertensive regimen in individuals at risk for mild cognitive impairment (MCI) and probable dementia (PD).

Design, Setting, and Participants

Active comparator, new-user observational cohort study design using data from the Systolic Blood Pressure Intervention Trial (SPRINT), conducted November 2010 through July 2018. Marginal cause-specific hazard ratios (HRs) and treatment-specific cumulative incidence functions were estimated with inverse probability (IP) weighting to account for confounding. Participants were using neither an ARB nor ACEI at baseline. Data analysis was conducted from April 7, 2021, to April 26, 2022.

Exposures

New users of ARB vs ACEI during the first 12 months of trial follow-up.

Main Outcomes and Measures

Composite of adjudicated amnestic MCI or PD.

Results

Of 9361 participants, 727 and 1313 new users of an ARB or ACEI, respectively, with well-balanced baseline characteristics between medication exposure groups after inverse probability weighting (mean [SD] age, 67 [9.5] years; 1291 ]63%] male; 240 [33%] Black; 89 [12%] Hispanic; 383 [53%] White; and 15 [2%] other race or ethnicity. In the primary analysis, during a median follow-up of 4.9 years, the inverse probability-weighted rate of amnestic MCI or PD was 4.3 vs 4.6 per 100 person-years among participants initiating ARB vs ACEI (HR, 0.93; 95% CI, 0.76-1.13). In subgroup analyses, new users of an ARB vs ACEI had a lower rate of amnestic MCI or PD among those in the standard systolic blood pressure treatment arm (HR, 0.61; 95% CI, 0.41-0.91) but not in the intensive arm (HR, 1.17; 95% CI, 0.90-1.52) (P = .007 for interaction).

Conclusions and Relevance

In this observational cohort study of US adults at high cardiovascular disease risk, there was no difference in the rate of amnestic MCI or PD among new users of an ARB compared with ACEI, although 95% CIs were wide.

Kidney Disease, Hypertension Treatment, and Cerebral Perfusion and Structure

RATIONALE & OBJECTIVE

The safety of intensive blood pressure (BP) targets is controversial for persons with chronic kidney disease (CKD). We studied the effects of hypertension treatment on cerebral perfusion and structure in individuals with and without CKD.

STUDY DESIGN

Neuroimaging substudy of a randomized trial.

SETTING & PARTICIPANTS

A subset of participants in the Systolic Blood Pressure Intervention Trial (SPRINT) who underwent brain magnetic resonance imaging studies. Presence of baseline CKD was assessed by estimated glomerular filtration rate (eGFR) and urinary albumin-creatinine ratio (UACR).

INTERVENTION

Participants were randomly assigned to intensive (systolic BP <120 mm Hg) versus standard (systolic BP <140 mm Hg) BP lowering.

OUTCOMES

The magnetic resonance imaging outcome measures were the 4-year change in global cerebral blood flow (CBF), white matter lesion (WML) volume, and total brain volume (TBV).

RESULTS

A total of 716 randomized participants with a mean age of 68 years were enrolled; follow-up imaging occurred after a median 3.9 years. Among participants with eGFR <60 mL/min/1.73 m2 (n = 234), the effects of intensive versus standard BP treatment on change in global CBF, WMLs, and TBV were 3.38 (95% CI, 0.32 to 6.44) mL/100 g/min, -0.06 (95% CI, -0.16 to 0.04) cm3 (inverse hyperbolic sine-transformed), and -3.8 (95% CI, -8.3 to 0.7) cm3, respectively. Among participants with UACR >30 mg/g (n = 151), the effects of intensive versus standard BP treatment on change in global CBF, WMLs, and TBV were 1.91 (95% CI, -3.01 to 6.82) mL/100 g/min, 0.003 (95% CI, -0.13 to 0.13) cm3 (inverse hyperbolic sine-transformed), and -7.0 (95% CI, -13.3 to -0.3) cm3, respectively. The overall treatment effects on CBF and TBV were not modified by baseline eGFR or UACR; however, the effect on WMLs was attenuated in participants with albuminuria (P = 0.04 for interaction).

LIMITATIONS

Measurement variability due to multisite design.

CONCLUSIONS

Among adults with hypertension who have primarily early kidney disease, intensive versus standard BP treatment did not appear to have a detrimental effect on brain perfusion or structure. The findings support the safety of intensive BP treatment targets on brain health in persons with early kidney disease.

FUNDING

SPRINT was funded by the National Institutes of Health (including the National Heart, Lung, and Blood Institute; the National Institute of Diabetes and Digestive and Kidney Diseases; the National Institute on Aging; and the National Institute of Neurological Disorders and Stroke), and this substudy was funded by the National Institutes of Diabetes and Digestive and Kidney Diseases.

TRIAL REGISTRATION

SPRINT was registered at ClinicalTrials.gov with study number NCT01206062.

Medical Image-Based Computational Fluid Dynamics and Fluid-Structure Interaction Analysis in Vascular Diseases

Hemodynamic factors, induced by pulsatile blood flow, play a crucial role in vascular health and diseases, such as the initiation and progression of atherosclerosis. Computational fluid dynamics, finite element analysis, and fluid-structure interaction simulations have been widely used to quantify detailed hemodynamic forces based on vascular images commonly obtained from computed tomography angiography, magnetic resonance imaging, ultrasound, and optical coherence tomography. In this review, we focus on methods for obtaining accurate hemodynamic factors that regulate the structure and function of vascular endothelial and smooth muscle cells. We describe the multiple steps and recent advances in a typical patient-specific simulation pipeline, including medical imaging, image processing, spatial discretization to generate computational mesh, setting up boundary conditions and solver parameters, visualization and extraction of hemodynamic factors, and statistical analysis. These steps have not been standardized and thus have unavoidable uncertainties that should be thoroughly evaluated. We also discuss the recent development of combining patient-specific models with machine-learning methods to obtain hemodynamic factors faster and cheaper than conventional methods. These critical advances widen the use of biomechanical simulation tools in the research and potential personalized care of vascular diseases.

Association of Antihypertensives That Stimulate vs Inhibit Types 2 and 4 Angiotensin II Receptors With Cognitive Impairment

Importance

Use of antihypertensive medications that stimulate type 2 and 4 angiotensin II receptors, compared with those that do not stimulate these receptors, has been associated with a lower risk of dementia. However, this association with cognitive outcomes in hypertension trials, with blood pressure levels in the range of current guidelines, has not been evaluated.

Objective

To examine the association between use of exclusively antihypertensive medication regimens that stimulate vs inhibit type 2 and 4 angiotensin II receptors on mild cognitive impairment (MCI) or dementia.

Design, Setting, and Participants

This cohort study is a secondary analysis (April 2011 to July 2018) of participants in the randomized Systolic Blood Pressure Intervention Trial (SPRINT), which recruited individuals 50 years or older with hypertension and increased cardiovascular risk but without a history of diabetes, stroke, or dementia. Data analysis was conducted from March 16 to July 6, 2021.

Exposures

Prevalent use of angiotensin II receptor type 2 and 4-stimulating or -inhibiting antihypertensive medication regimens at the 6-month study visit.

Main Outcomes and Measures

The primary outcome was a composite of adjudicated amnestic MCI or probable dementia.

Results

Of the 8685 SPRINT participants who were prevalent users of antihypertensive medication regimens at the 6-month study visit (mean [SD] age, 67.7 [11.2] years; 5586 [64.3%] male; and 935 [10.8%] Hispanic, 2605 [30.0%] non-Hispanic Black, 4983 [57.4%] non-Hispanic White, and 162 [1.9%] who responded as other race or ethnicity), 2644 (30.4%) were users of exclusively stimulating, 1536 (17.7%) inhibiting, and 4505 (51.9%) mixed antihypertensive medication regimens. During a median of 4.8 years of follow-up (95% CI, 4.7-4.8 years), there were 45 vs 59 cases per 1000 person-years of amnestic MCI or probable dementia among prevalent users of regimens that contained exclusively stimulating vs inhibiting antihypertensive medications (hazard ratio [HR], 0.76; 95% CI, 0.66-0.87). When comparing stimulating-only vs inhibiting-only users, amnestic MCI occurred at rates of 40 vs 54 cases per 1000 person-years (HR, 0.74; 95% CI, 0.64-0.87) and probable dementia at rates of 8 vs 10 cases per 1000 person-years (HR, 0.80; 95% CI, 0.57-1.14). Negative control outcome analyses suggested the presence of residual confounding.

Conclusions and Relevance

In this secondary analysis of SPRINT, prevalent users of regimens that contain exclusively antihypertensive medications that stimulate vs inhibit type 2 and 4 angiotensin II receptors had lower rates of incident cognitive impairment. Residual confounding cannot be ruled out. If these results are replicated in randomized clinical trials, certain antihypertensive medications could be prioritized to prevent cognitive decline.

SPRINT Revisited: Updated Results and Implications

The SPRINT (Systolic Blood Pressure Intervention Trial) results have influenced clinical practice but have also generated discussion regarding the validity, generalizability, and importance of the findings. Following the SPRINT primary results manuscript in 2015, additional results and analyses of the data have addressed these concerns. The primary objective of this article is to respond to key questions that have been raised.

Abnormalities in Cardiac Structure and Function among Individuals with CKD: The COMBINE Trial

Background

Individuals with CKD have a high burden of cardiovascular disease (CVD). Abnormalities in cardiac structure and function represent subclinical CVD and can be assessed by cardiac magnetic resonance imaging (cMRI).

Methods

We investigated differences in cMRI parameters in 140 individuals with CKD stages 3b-4 who participated in the CKD Optimal Management with BInders and NicotinamidE (COMBINE) trial and in 24 age- and sex-matched healthy volunteers. Among COMBINE participants, we examined the associations of eGFR, urine albumin-creatinine ratio (UACR), phosphate, fibroblast growth factor 23 (FGF23), and parathyroid hormone (PTH) with baseline (N=140) and 12-month change (N=112) in cMRI parameters.

Results

Mean (SD) ages of the COMBINE participants and healthy volunteers were 64.9 (11.9) and 60.4 (7.3) years, respectively. The mean (SD) baseline eGFR values in COMBINE participants were 32.1 (8.0) and 85.9 (16.0) ml/min per 1.73 m² in healthy volunteers. The median (interquartile range [IQR]) UACR in COMBINE participants was 154 (20.3-540.0) mg/g. Individuals with CKD had lower mitral valve E/A ratio compared with healthy volunteers (for CKD versus non-CKD, β estimate, -0.13; 95% CI, -0.24 to -0.012). Among COMBINE participants, multivariable linear regression analyses showed that higher UACR was significantly associated with lower mitral valve E/A ratio (β estimate per 1 unit increase in natural-log UACR, -0.06; 95% CI, -0.09 to -0.03). This finding was preserved among individuals without baseline CVD. UACR was not associated with 12-month change in any cMRI parameter. eGFR, phosphate, FGF23, and PTH were not associated with any cMRI parameter in cross-sectional or change analyses.

Conclusions

Individuals with CKD stages 3b-4 have evidence of cMRI abnormalities. Albuminuria was independently associated with diastolic dysfunction, as assessed by mitral valve E/A ratio, in individuals with CKD with and without clinical CVD. Albuminuria was not associated with change in any cMRI parameter.

Arteriovenous Fistula Maturation, Functional Patency, and Intervention Rates

Importance

National initiatives have emphasized the use of autogenous arteriovenous fistulas (AVFs) for hemodialysis, but their purported benefits have been questioned.

Objective

To examine AVF usability, longer-term functional patency, and remedial procedures to facilitate maturation, manage complications, or maintain patency in the Hemodialysis Fistula Maturation (HFM) Study.

Design, Setting, and Participants

The HFM Study was a multicenter (n = 7) prospective National Institutes of Health National Institute of Diabetes and Digestive and Kidney Diseases cohort study performed to identify factors associated with AVF maturation. A total of 602 participants were enrolled (dialysis, kidney failure: 380; predialysis, chronic kidney disease [CKD]: 222) with AVF maturation ascertained for 535 (kidney failure, 353; CKD, 182) participants.

Interventions

All clinical decisions regarding AVF management were deferred to the individual centers, but remedial interventions were discouraged within 6 weeks of creation.

Main Outcomes and Measures

In this case series analysis, the primary outcome was unassisted maturation. Functional patency, freedom from intervention, and participant survival were summarized using Kaplan-Meier analysis.

Results

Most participants evaluated (n = 535) were men (372 [69.5%]) and had diabetes (311 [58.1%]); mean (SD) age was 54.6 (13.6) years. Almost two-thirds of the AVFs created (342 of 535 [64%]) were in the upper arm. The AVF maturation rates for the kidney failure vs CKD participants were 29% vs 10% at 3 months, 67% vs 38% at 6 months, and 76% vs 58% at 12 months. Several participants with kidney failure (133 [37.7%]) and CKD (63 [34.6%]) underwent interventions to facilitate maturation or manage complications before maturation. The median time from access creation to maturation was 115 days (interquartile range [IQR], 86-171 days) but differed by initial indication (CKD, 170 days; IQR, 113-269 days; kidney failure, 105 days; IQR, 81-137 days). The functional patency for the AVFs that matured at 1 year was 87% (95% CI, 83.2%-90.2%) and at 2 years, 75% (95% CI, 69.7%-79.7%), and there was no significant difference for those receiving interventions before maturation. Almost half (188 [47.5%]) of the AVFs that matured had further intervention to maintain patency or treat complications.

Conclusions and Relevance

The findings of this study suggest that AVF remains an accepted hemodialysis access option, although both its maturation and continued use require a moderate number of interventions to maintain patency and treat the associated complications.

Management of Blood Pressure in Patients With Chronic Kidney Disease Not Receiving Dialysis: Synopsis of the 2021 KDIGO Clinical Practice Guideline

DESCRIPTION

The Kidney Disease: Improving Global Outcomes (KDIGO) 2021 clinical practice guideline for the management of blood pressure (BP) in patients with chronic kidney disease (CKD) not receiving dialysis is an update of the KDIGO 2012 guideline on the same topic and reflects new evidence on the risks and benefits of BP-lowering therapy among patients with CKD. It is intended to support shared decision making by health care professionals working with patients with CKD worldwide. This article is a synopsis of the full guideline.

METHODS

The KDIGO leadership commissioned 2 co-chairs to convene an international Work Group of researchers and clinicians. After a Controversies Conference in September 2017, the Work Group defined the scope of the evidence review, which was undertaken by an evidence review team between October 2017 and April 2020. Evidence reviews were done according to the Cochrane Handbook. The GRADE (Grading of Recommendations Assessment, Development and Evaluation) approach was used to guide the development of the recommendations and rate the strength and quality of the evidence. Practice points were included to provide guidance when evidence was insufficient to make a graded recommendation. The guideline was revised after public consultation between January and March 2020.

RECOMMENDATIONS

The updated guideline comprises 11 recommendations and 20 practice points. This synopsis summarizes key recommendations pertinent to the diagnosis and management of high BP in adults with CKD, excluding those receiving kidney replacement therapy. In particular, the synopsis focuses on recommendations for standardized BP measurement and a target systolic BP of less than 120 mm Hg, because these recommendations differ from some other guidelines.

Clinical events and patient-reported outcome measures during CKD progression: findings from the Chronic Renal Insufficiency Cohort Study

BACKGROUND

Patients with chronic kidney disease (CKD) face risks of not only end-stage kidney disease (ESKD), cardiovascular disease (CVD) and death, but also decline in kidney function, quality of life (QOL) and mental and physical well-being. This study describes the multidimensional trajectories of CKD using clinical events, kidney function and patient-reported outcome measures (PROMs). We hypothesized that more advanced CKD stages would associate with more rapid decline in each outcome.

METHODS

Among 3939 participants enrolled in the Chronic Renal Insufficiency Cohort (CRIC) Study, we evaluated multidimensional disease trajectories by G- and A-stages of enrollment estimated glomerular filtration rate (eGFR) and albuminuria, respectively. These trajectories included clinical events (ESKD, CVD, heart failure and death), eGFR decline and PROMs [kidney disease QOL (KDQOL) burden, effects and symptoms questionnaires, as well as the 12-item short form mental and physical component summaries]. We also evaluated a group-based multitrajectory model to group participants on the basis of longitudinal PROMs and compared group assignments by enrollment G- and A-stage.

RESULTS

The mean participant age was 58 years, 45% were women, mean baseline eGFR was 44 mL/min/1.73 m2 and median urine albumin:creatinine ratio was 52 mg/g. The incidence of all clinical events was greater and eGFR decline was faster with more advanced G- and A-stages. While baseline KDQOL and physical component measures were lower with more advanced G- and A-stage of CKD, changes in PROMs were inconsistently related to the baseline CKD stage. Groups formed on PROM trajectories were fairly distinct from existing CKD staging (observed agreement 60.6%) and were associated with the risk of ESKD, CVD, heart failure and death.

CONCLUSIONS

More advanced baseline CKD stage was associated with a higher risk of clinical events and faster eGFR decline, and was only weakly related to changes in patient-reported metrics over time.

Commentary on the KDIGO 2021 Clinical Practice Guideline for the Management of Blood Pressure in CKD

PURPOSE OF REVIEW

To summarize and explain the new guideline on blood pressure (BP) management in chronic kidney disease (CKD) published by Kidney Disease: Improving Global Outcomes (KDIGO), an independent global nonprofit organization which develops and implements evidence-based clinical practice guidelines in kidney disease. KDIGO issued its first clinical practice guideline for the Management of Blood Pressure (BP) in Chronic Kidney Disease (CKD) for patients not receiving dialysis in 2012 and now updated the guideline in 2021.

RECENT FINDINGS

Recommendations in this update were developed based on systematic literature reviews and appraisal of the quality of the evidence and strength of recommendation following the "Grading of Recommendations Assessment, Development and Evaluation" (GRADE) approach. The updated guideline includes five chapters covering BP measurement techniques, lifestyle interventions for lowering BP, and management of BP in three target populations, namely adults (with and without diabetes), kidney transplant recipients, and children. A dedicated chapter on BP measurement emphasizing standardized preparation and measurement protocols for office BP measurement is a new addition, following protocols used in large randomized trials of BP targets with pivotal clinical outcomes. Based on the available evidence, and in particular in the CKD subgroup of the SPRINT trial, the 2021 guideline suggests a systolic BP target of <120 mm Hg, based on standardized measurements, for most individuals with CKD not receiving dialysis, with the exception of kidney transplant recipients and children. This recommendation is strictly contingent on the measurement of BP using standardized office readings and not routine office readings.

Final Report of a Trial of Intensive versus Standard Blood-Pressure Control

BACKGROUND

In a previously reported randomized trial of standard and intensive systolic blood-pressure control, data on some outcome events had yet to be adjudicated and post-trial follow-up data had not yet been collected.

METHODS

We randomly assigned 9361 participants who were at increased risk for cardiovascular disease but did not have diabetes or previous stroke to adhere to an intensive treatment target (systolic blood pressure, <120 mm Hg) or a standard treatment target (systolic blood pressure, <140 mm Hg). The primary outcome was a composite of myocardial infarction, other acute coronary syndromes, stroke, acute decompensated heart failure, or death from cardiovascular causes. Additional primary outcome events occurring through the end of the intervention period (August 20, 2015) were adjudicated after data lock for the primary analysis. We also analyzed post-trial observational follow-up data through July 29, 2016.

RESULTS

At a median of 3.33 years of follow-up, the rate of the primary outcome and all-cause mortality during the trial were significantly lower in the intensive-treatment group than in the standard-treatment group (rate of the primary outcome, 1.77% per year vs. 2.40% per year; hazard ratio, 0.73; 95% confidence interval [CI], 0.63 to 0.86; all-cause mortality, 1.06% per year vs. 1.41% per year; hazard ratio, 0.75; 95% CI, 0.61 to 0.92). Serious adverse events of hypotension, electrolyte abnormalities, acute kidney injury or failure, and syncope were significantly more frequent in the intensive-treatment group. When trial and post-trial follow-up data were combined (3.88 years in total), similar patterns were found for treatment benefit and adverse events; however, rates of heart failure no longer differed between the groups.

CONCLUSIONS

Among patients who were at increased cardiovascular risk, targeting a systolic blood pressure of less than 120 mm Hg resulted in lower rates of major adverse cardiovascular events and lower all-cause mortality than targeting a systolic blood pressure of less than 140 mm Hg, both during receipt of the randomly assigned therapy and after the trial. Rates of some adverse events were higher in the intensive-treatment group. (Funded by the National Institutes of Health; SPRINT ClinicalTrials.gov number, NCT01206062.).

Angiotensin II receptor blocker or angiotensin-converting enzyme inhibitor use and COVID-19-related outcomes among US Veterans

BACKGROUND

Angiotensin II receptor blockers (ARBs) and angiotensin-converting enzyme inhibitors (ACEIs) may positively or negatively impact outcomes in severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. We investigated the association of ARB or ACEI use with coronavirus disease 2019 (COVID-19)-related outcomes in US Veterans with treated hypertension using an active comparator design, appropriate covariate adjustment, and negative control analyses.

METHODS AND FINDINGS

In this retrospective cohort study of Veterans with treated hypertension in the Veterans Health Administration (01/19/2020-08/28/2020), we compared users of (A) ARB/ACEI vs. non-ARB/ACEI (excluding Veterans with compelling indications to reduce confounding by indication) and (B) ARB vs. ACEI among (1) SARS-CoV-2+ outpatients and (2) COVID-19 hospitalized inpatients. The primary outcome was all-cause hospitalization or mortality (outpatients) and all-cause mortality (inpatients). We estimated hazard ratios (HR) using propensity score-weighted Cox regression. Baseline characteristics were well-balanced between exposure groups after weighting. Among outpatients, there were 5.0 and 6.0 primary outcomes per 100 person-months for ARB/ACEI (n = 2,482) vs. non-ARB/ACEI (n = 2,487) users (HR 0.85, 95% confidence interval [CI] 0.73-0.99, median follow-up 87 days). Among outpatients who were ARB (n = 4,877) vs. ACEI (n = 8,704) users, there were 13.2 and 14.8 primary outcomes per 100 person-months (HR 0.91, 95%CI 0.86-0.97, median follow-up 85 days). Among inpatients who were ARB/ACEI (n = 210) vs. non-ARB/ACEI (n = 275) users, there were 3.4 and 2.0 all-cause deaths per 100 person months (HR 1.25, 95%CI 0.30-5.13, median follow-up 30 days). Among inpatients, ARB (n = 1,164) and ACEI (n = 2,014) users had 21.0 vs. 17.7 all-cause deaths, per 100 person-months (HR 1.13, 95%CI 0.93-1.38, median follow-up 30 days).

CONCLUSIONS

This observational analysis supports continued ARB or ACEI use for patients already using these medications before SARS-CoV-2 infection. The novel beneficial association observed among outpatients between users of ARBs vs. ACEIs on hospitalization or mortality should be confirmed with randomized trials.

Heart Failure Hospitalization Risk associated with Iron Status in Veterans with CKD

BACKGROUND AND OBJECTIVES

CKD is an independent risk factor for heart failure. Iron dysmetabolism potentially contributes to heart failure, but this relationship has not been well characterized in CKD.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

We performed a historical cohort study using data from the Veterans Affairs Corporate Data Warehouse to evaluate the relationship between iron status and heart failure hospitalization. We identified a CKD cohort with at least one set of iron indices between 2006 and 2015. The first available date of serum iron indices was identified as the study index date. The cohort was divided into four iron groups on the basis of the joint quartiles of serum transferrin saturation (shown in percent) and ferritin (shown in nanograms per milliliter): reference (16%-28%, 55-205 ng/ml), low iron (0.4%-16%, 0.9-55 ng/ml), high iron (28%-99.5%, 205-4941 ng/ml), and function iron deficiency (0.8%-16%, 109-2783 ng/ml). We compared 1-year heart failure hospitalization risk between the iron groups using matching weights derived from multinomial propensity score models and Poisson rate-based regression.

RESULTS

A total of 78,551 veterans met the eligibility criteria. The covariates were well balanced among the iron groups after applying the propensity score weights (n=31,819). One-year adjusted relative rate for heart failure hospitalization in the iron deficiency groups were higher compared with the reference group (low iron: 1.29 [95% confidence interval, 1.19 to 1.41]; functional iron deficiency: 1.25 [95% confidence interval, 1.13 to 1.37]). The high-iron group was associated with lower 1-year relative rate of heart failure hospitalization (0.82; 95% confidence interval, 0.72 to 0.92). Furthermore, the association between iron deficiency and heart failure hospitalization risk remained consistent regardless of the diabetes status or heart failure history at baseline.

CONCLUSIONS

Iron deficiency, regardless of cause, was associated with higher heart failure hospitalization risk in CKD. Higher iron status was associated with lower heart failure hospitalization risks.

Longitudinal Changes in Prorenin and Renin in the Chronic Renal Insufficiency Cohort

INTRODUCTION

Prorenin, a precursor of renin, and renin play an important role in regulation of the renin-angiotensin system. More recently, receptor-bound prorenin has been shown to activate intracellular signaling pathways that mediate fibrosis, independent of angiotensin II. Prorenin and renin may thus be of physiologic significance in CKD, but their plasma concentrations have not been well characterized in CKD.

METHODS

We evaluated distribution and longitudinal changes of prorenin and renin concentrations in the plasma samples collected at follow-up years 1, 2, 3, and 5 of the Chronic Renal Insufficiency Cohort (CRIC) study, an ongoing longitudinal observational study of 3,939 adults with CKD. Descriptive statistics and multivariable regression of log-transformed values were used to describe cross-sectional and longitudinal variation and associations with participant characteristics.

RESULTS

A total of 3,361 CRIC participants had plasma available for analysis at year 1. The mean age (±standard deviation, SD) was 59 ± 11 years, and the mean estimated glomerular filtration rate (eGFR, ± SD) was 43 ± 17 mL/min per 1.73 m2. Median (interquartile range) values of plasma prorenin and renin at study entry were 4.4 (2.1, 8.8) ng/mL and 2.0 (0.8, 5.9) ng/dL, respectively. Prorenin and renin were positively correlated (Spearman correlation 0.51, p < 0.001) with each other. Women and non-Hispanic blacks had lower prorenin and renin values at year 1. Diabetes, lower eGFR, and use of angiotensin-converting enzyme inhibitors, angiotensin receptor blockers, statins, and diuretics were associated with higher levels. Prorenin and renin decreased by a mean of 2 and 5% per year, respectively. Non-Hispanic black race and eGFR <30 mL/min/1.73 m2 at year 1 predicted a steeper decrease in prorenin and renin over time. In addition, each increase in urinary sodium excretion by 2 SDs at year 1 increased prorenin and renin levels by 4 and 5% per year, respectively.

DISCUSSION/CONCLUSIONS

The cross-sectional clinical factors associated with prorenin and renin values were similar. Overall, both plasma prorenin and renin concentrations decreased over the years, particularly in those with severe CKD at study entry.

Executive summary of the KDIGO 2021 Clinical Practice Guideline for the Management of Blood Pressure in Chronic Kidney Disease

The Kidney Disease: Improving Global Outcomes (KDIGO) 2021 Clinical Practice Guideline for the Management of Blood Pressure in Chronic Kidney Disease for patients not receiving dialysis represents an update to the KDIGO 2012 guideline on this topic. Development of this guideline update followed a rigorous process of evidence review and appraisal. Guideline recommendations are based on systematic reviews of relevant studies and appraisal of the quality of the evidence. The strength of recommendations is based on the "Grading of Recommendations Assessment, Development and Evaluation" (GRADE) approach. The scope includes topics covered in the original guideline, such as optimal blood pressure targets, lifestyle interventions, antihypertensive medications, and specific management in kidney transplant recipients and children. Some aspects of general and cardiovascular health, such as lipid and smoking management, are excluded. This guideline also introduces a chapter dedicated to proper blood pressure measurement since all large randomized trials targeting blood pressure with pivotal outcomes used standardized preparation and measurement protocols adhered to by patients and clinicians. Based on previous and new evidence, in particular the Systolic Blood Pressure Intervention Trial (SPRINT) results, we propose a systolic blood pressure target of less than 120 mm Hg using standardized office reading for most people with chronic kidney disease (CKD) not receiving dialysis, the exception being children and kidney transplant recipients. The goal of this guideline is to provide clinicians and patients a useful resource with actionable recommendations supplemented with practice points. The burden of the recommendations on patients and resources, public policy implications, and limitations of the evidence are taken into consideration. Lastly, knowledge gaps and recommendations for future research are provided.

Management of Cardiovascular Disease in Kidney Disease Study: Rationale and Design

INTRODUCTION

Atherosclerosis, inflammation, and vascular stiffness are prominent interrelated risk factors contributing to the high incidence of cardiovascular disease (CVD) in patients with CKD. Conventional CVD management strategies in CKD largely target atherosclerotic CVD and have had a limited impact on the cardiovascular mortality in this population. Multiple in vivo and in vitro studies and epidemiological evidence from the rheumatologic cohorts have shown that low-dose hydroxychloroquine has beneficial effects on inflammation, endothelial function, insulin sensitivity, and metabolic syndrome. Our recent proof-of-concept animal study showed that hydroxychloroquine has marked protection against atherosclerosis and vascular stiffness. We hypothesize that hydroxychloroquine has the potential to provide significant cardiovascular benefits in patients with CKD.

METHODS

The Management of Cardiovascular disease in Kidney disease study (NCT03636152) is a phase 2B, randomized, double-blind, placebo-controlled trial evaluating the effects of low-dose hydroxychloroquine therapy on the parameters of atherosclerosis, inflammation, and vascular stiffness in patients with CKD. The study plans to enroll 100 CKD patients estimated to be at high cardiovascular risk by a combination of low estimated glomerular filtration rate and albuminuria and treat them for 18 months with hydroxychloroquine or placebo in 1:1 allocation.

RESULTS

The study will assess the change in the total carotid plaque volume as measured by serial noncontrast carotid MRI as the primary outcome and the serial changes in plasma inflammation markers, vascular stiffness, renal function, and the composition characteristics of the carotid plaque as secondary outcome measures.

DISCUSSION/CONCLUSION

The results of this trial will provide the proof-of-applicability for hydroxychloroquine in the CVD in CKD. If positive, this trial should lead to phase-3 trials with clinical end points for this potentially transformative, novel, and inexpensive therapy for CVD in CKD.

Chronic kidney disease, atherosclerotic plaque characteristics on carotid magnetic resonance imaging, and cardiovascular outcomes

Background

It is unclear whether faster progression of atherosclerosis explains the higher risk of cardiovascular events in CKD. The objectives of this study were to 1. Characterize the associations of CKD with presence and morphology of atherosclerotic plaques on carotid magnetic resonance imaging (MRI) and 2. Examine the associations of baseline CKD and carotid atherosclerotic plaques with subsequent cardiovascular events.

Methods

In a subgroup (N = 465) of Systolic Blood Pressure Intervention Trial.

(SPRINT) participants, we measured carotid plaque presence and morphology at baseline and after 30-months with MRI. We examined the associations of CKD (baseline eGFR < 60 ml/min/1.73m²) with progression of carotid plaques and the SPRINT cardiovascular endpoint.

Results

One hundred and ninety six (42%) participants had CKD. Baseline eGFR in the non-CKD and CKD subgroups were 77 ± 14 and 49 ± 8 ml/min/1.73 m², respectively. Lipid rich necrotic-core plaque was present in 137 (29.5%) participants. In 323 participants with both baseline and follow-up MRI measurements of maximum wall thickness, CKD was not associated with progression of maximum wall thickness (OR 0.62, 95% CI 0.36 to 1.07, p = 0.082). In 96 participants with necrotic core plaque at baseline and with a valid follow-up MRI, CKD was associated with lower odds of progression of necrotic core plaque (OR 0.41, 95% CI 0.17 to 0.95, p = 0.039). There were 28 cardiovascular events over 1764 person-years of follow-up. In separate Cox models, necrotic core plaque (HR 2.59, 95% CI 1.15 to 5.85) but not plaque defined by maximum wall thickness or presence of a plaque component (HR 1.79, 95% CI 0.73 to 4.43) was associated with cardiovascular events. Independent of necrotic core plaque, CKD (HR 3.35, 95% CI 1.40 to 7.99) was associated with cardiovascular events.

Conclusions

Presence of necrotic core in carotid plaque rather than the presence of plaque per se was associated with increased risk of cardiovascular events. We did not find CKD to be associated with faster progression of necrotic core plaques, although both were independently associated with cardiovascular events. Thus, CKD may contribute to cardiovascular disease principally via mechanisms other than atherosclerosis such as arterial media calcification or stiffening.

Trial Registration

NCT01475747, registered on November 21, 2011.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12882-021-02260-x.

FGF23, Frailty, and Falls in SPRINT

BACKGROUND/OBJECTIVES

Chronic kidney disease (CKD) is associated with frailty. Fibroblast growth factor 23 (FGF23) is elevated in CKD and associated with frailty among non-CKD older adults and individuals with human immunodeficiency virus. Whether FGF23 is associated with frailty and falls in CKD is unknown.

DESIGN

Cross-sectional and longitudinal observational study.

SETTING

Systolic Blood Pressure Intervention Trial (SPRINT), a randomized trial evaluating standard (systolic blood pressure [SBP] <140 mm Hg) versus intensive (SBP <120 mm Hg) blood pressure lowering on cardiovascular and cognitive outcomes among older adults without diabetes mellitus.

PARTICIPANTS

A total of 2,376 participants with CKD (estimated glomerular filtration rate [eGFR] <60 mL/min/1.73 m² ).

MEASUREMENTS

The exposure variable was intact FGF23. We used multinomial logistic regression to determine the cross-sectional association of intact FGF23 with frailty and Cox proportional hazards analysis to determine the longitudinal association with incident falls. Models were adjusted for demographics, comorbidities, randomization group, antihypertensives, eGFR, mineral metabolism markers, and frailty.

RESULTS

After adjustment, the odds ratio for prevalent frailty versus non-frailty per twofold higher FGF23 was 1.34 (95% confidence interval [CI] = 1.01-1.77). FGF23 levels in the highest quartile versus the lowest quartile demonstrated more than a twofold increased fall risk (hazard ratio [HR] = 2.32; 95% CI = 1.26-4.26), and the HR per twofold higher FGF23 was 1.99 (95% CI = 1.48-2.68).

CONCLUSION

Among SPRINT participants with CKD, FGF23 was associated with prevalent frailty and falls.

Analyses of hemodialysis arteriovenous fistula geometric configuration and its associations with maturation and reintervention

OBJECTIVE

An arteriovenous fistula (AVF) is the preferred vascular access for chronic hemodialysis; however, the rates of AVF maturation failure and reintervention remain high. We investigated the AVF geometric parameters and their associations with AVF physiologic maturation and reintervention in a prospective multicenter study.

METHODS

From 2011 to 2016, patients undergoing vein end-to-artery side upper extremity AVF creation surgery were recruited. Contrast-free dark blood and phase-contrast magnetic resonance imaging (MRI) scans were performed using 3.0T scanners to obtain the AVF lumen geometry and flow rates, respectively, at postoperative day 1, week 6, and month 6. The arteriovenous anastomosis angle, nonplanarity, and tortuosity of the fistula were calculated according to the lumen centerlines. AVFs were considered physiologically matured if, using the week 6 MRI data, the flow rate was ≥500 mL/min and the minimum vein lumen diameter was ≥5 mm. The associations of these geometric parameters with AVF maturation and reintervention due to perianastomotic and mid-vein stenosis within 1 year were assessed.

RESULTS

A total of 111 patients had a usable day 1 MRI scan, with most having upper arm AVFs (n = 73). Compared with the forearm AVFs, upper arm AVFs had greater anastomosis angles (P < .001), larger deviations from a plane (nonplanarity; P = .002), and more prominent tortuosity (P = .038) at day 1. These parameters significantly increased between day 1 and week 6 in upper arm AVFs. In contrast, significant changes in these parameters in forearm AVFs were not observed. The rate of maturation was 54% and 86% for forearm and upper arm AVFs, respectively. None of the geometric parameters at day 1 were associated with AVF maturation in either location. The rate of reintervention was 24% and 30% for forearm and upper arm AVFs, respectively, with a larger nonplanarity angle at day 1 associated with less reintervention (30° ± 15° vs 21° ± 10°; P = .034) in upper arm AVFs only. This relationship was unchanged after adjusting for age, sex, race, dialysis status, or diabetes.

CONCLUSIONS

In our study, upper arm fistulas had a larger anastomosis angle, were more nonplanar, and had more tortuous veins than forearm fistulas. For upper arm fistulas, a larger nonplanarity angle is associated with a lower rate of reintervention within 1 year. Once confirmed, vascular surgeons could consider increasing the nonplanarity angle by incorporating a tension-free gentle curvature in the proximal segment of the mobilized vein to reduce reinterventions when creating an upper arm fistula.

Tubular Biomarkers and Chronic Kidney Disease Progression in SPRINT Participants

BACKGROUND

Kidney tubular atrophy on biopsy is a strong predictor of chronic kidney disease (CKD) progression, but tubular health is poorly quantified by traditional measures including estimated glomerular filtration rate (eGFR) and albuminuria. We hypothesized that urinary biomarkers of impaired tubule function would be associated with faster eGFR declines in persons with CKD.

METHODS

We measured baseline urine concentrations of uromodulin, β2-microglobulin (β2m), and α1-microglobulin (α1m) among 2,428 participants of the Systolic Blood Pressure Intervention Trial with an eGFR <60 mL/min/1.73 m2. We used linear mixed models to evaluate biomarker associations with annualized relative change in eGFR, stratified by randomization arm.

RESULTS

At baseline, the mean age was 73 ± 9 years and eGFR was 46 ± 11 mL/min/1.73 m2. In the standard blood pressure treatment arm, each 2-fold higher urinary uromodulin was associated with slower % annual eGFR decline (0.34 [95% CI: 0.08, 0.60]), whereas higher urinary β2m was associated with faster % annual eGFR decline (-0.10 [95% CI: -0.18, -0.02]) in multivariable-adjusted models including baseline eGFR and albuminuria. Associations were weaker and did not reach statistical significance in the intensive blood pressure treatment arm for either uromodulin (0.11 [-0.13, 0.35], p value for interaction by treatment arm = 0.045) or β2m (-0.01 [-0.08, 0.08], p value for interaction = 0.001). Urinary α1m was not independently associated with eGFR decline in the standard (0.01 [-0.22, 0.23]) or intensive (0.03 [-0.20, 0.25]) arm.

CONCLUSIONS

Among trial participants with hypertension and CKD, baseline measures of tubular function were associated with subsequent declines in kidney function, although these associations were diminished by intensive blood pressure control.

The Influence of Baseline Diastolic Blood Pressure on the Effects of Intensive Blood Pressure Lowering on Cardiovascular Outcomes and All-Cause Mortality in Type 2 Diabetes

OBJECTIVE

To examine whether low baseline diastolic blood pressure (DBP) modifies the effects of intensive systolic blood pressure (SBP) lowering on cardiovascular outcomes in type 2 diabetes mellitus (T2DM).

RESEARCH DESIGN AND METHODS

The Action to Control Cardiovascular Risk in Diabetes Blood Pressure trial (ACCORD BP), a two-by-two factorial randomized controlled trial, examined effects of SBP (<120 vs. <140 mmHg) and glycemic (HbA1c <6% vs. 7.0-7.9% [<42 vs. 53-63 mmol/mol]) control on cardiovascular events in T2DM (N = 4,731). We examined whether effects of SBP control on cardiovascular composite were modified by baseline DBP and glycemic control.

RESULTS

Intensive SBP lowering decreased the risk of the cardiovascular composite (hazard ratio [HR] 0.76 [95% CI 0.59-0.98]) in the standard glycemic arm but not in the intensive glycemic arm (HR 1.06 [95% CI 0.81-1.40]). Spline regression models relating the effects of the intervention on the cardiovascular composite across the range of baseline DBP did not show evidence of effect modification by low baseline DBP for the cardiovascular composite in the standard or intensive glycemic arms. The relation between the effect of the intensive SBP intervention and baseline DBP was similar between glycemic arms for the cardiovascular composite three-way interaction (P = 0.83).

CONCLUSIONS

In persons with T2DM, intensive SBP lowering decreased the risk of cardiovascular composite end point irrespective of baseline DBP in the setting of standard glycemic control. Hence, low baseline DBP should not be an impediment to intensive SBP lowering in patients with T2DM treated with guideline-recommended standard glycemic control.

The Anastomotic Angle of Hemodialysis Arteriovenous Fistula Is Associated With Flow Disturbance at the Venous Stenosis Location on Angiography

The juxta-anastomotic stenosis of an arteriovenous fistula (AVF) is a significant clinical problem in hemodialysis patients with no effective treatment. Previous studies of AV anastomotic angles on hemodynamics and vascular wall injury were based on computational fluid dynamics (CFD) simulations using standardized AVF geometry, not the real-world patient images. The present study is the first CFD study to use angiographic images with patient-specific outcome information, i.e., the exact location of the AVF stenotic lesion. We conducted the CFD analysis utilizing patient-specific AVF geometric models to investigate hemodynamic parameters at different locations of an AVF, and the association between hemodynamic parameters and the anastomotic angle, particularly at the stenotic location. We analyzed 27 patients who used radio-cephalic AVF for hemodialysis and received an angiographic examination for juxta-anastomotic stenosis. The three-dimensional geometrical model of each patient's AVF was built using the angiographic images, in which the shape and the anastomotic angle of the AVF were depicted. CFD simulations of AVF hemodynamics were conducted to obtain blood flow parameters at different locations of an AVF. We found that at the location of the stenotic lesion, the AV angle was significantly correlated with access flow disturbance (r = 0.739; p < 0.001) and flow velocity (r = 0.563; p = 0.002). Furthermore, the receiver operating characteristic (ROC) curve analysis revealed that the AV angle determines the lesion's flow disturbance with a high area under the curve value of 0.878. The ROC analysis also identified a cut-off value of the AV angle as 46.5°, above or below which the access flow disturbance was significantly different. By applying CFD analysis to real-world patient images, the present study provides evidence that an anastomotic angle wider than 46.5° might lead to disturbed flow generation, demonstrating a reference angle to adopt during the anastomosis surgery.

Kidney Functional Magnetic Resonance Imaging and Change in eGFR in Individuals with CKD

BACKGROUND AND OBJECTIVES

Kidney functional magnetic resonance imaging (MRI) requires further investigation to enhance the noninvasive identification of patients at high risk of CKD progression.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

In this exploratory study, we obtained baseline diffusion-weighted and blood oxygen level-dependent MRI in 122 participants of the CKD Optimal Management with Binders and Nicotinamide trial, which was a multicenter, randomized, double-blinded, 12-month, four-group parallel trial of nicotinamide and lanthanum carbonate versus placebo conducted in individuals with eGFR 20-45 ml/min per 1.73 m². Lower values of apparent diffusion coefficient (ADC) on diffusion-weighted MRI may indicate increased fibrosis, and higher values of relaxation rate (R2*) on blood oxygen level-dependent MRI may represent decreased oxygenation. Because there was no effect of active treatment on eGFR over 12 months, we tested whether baseline kidney functional MRI biomarkers were associated with eGFR decline in all 122 participants. In a subset of 87 participants with 12-month follow-up MRI data, we evaluated whether kidney functional MRI biomarkers change over time.

RESULTS

Mean baseline eGFR was 32±9 ml/min per 1.73 m², and mean annual eGFR slope was -2.3 (95% confidence interval [95% CI], -3.4 to -1.1) ml/min per 1.73 m² per year. After adjustment for baseline covariates, baseline ADC was associated with change in eGFR over time (difference in annual eGFR slope per 1 SD increase in ADC: 1.3 [95% CI, 0.1 to 2.5] ml/min per 1.73 m² per year, ADC×time interaction P=0.04). This association was no longer significant after further adjustment for albuminuria (difference in annual eGFR slope per 1 SD increase in ADC: 1.0 (95% CI, -0.1 to 2.2) ml/min per 1.73 m² per year, ADC×time interaction P=0.08). There was no significant association between baseline R2* and change in eGFR over time. In 87 participants with follow-up functional MRI, ADC and R2* values remained stable over 12 months (intraclass correlation: 0.71 and 0.68, respectively).

CONCLUSIONS

Baseline cortical ADC was associated with change in eGFR over time, but this association was not independent of albuminuria. Kidney functional MRI biomarkers remained stable over 1 year.

CLINICAL TRIAL REGISTRY NAME AND REGISTRATION NUMBER

CKD Optimal Management with Binders and Nicotinamide (COMBINE), NCT02258074.

Baseline Diastolic Blood Pressure and Cardiovascular Outcomes in SPRINT Participants with Chronic Kidney Disease

Background

We sought to determine whether intensive systolic BP (SBP) lowering was harmful in Systolic Blood Pressure Intervention Trial (SPRINT) participants with CKD (eGFR<60 ml/min per 1.73 m2) and lower baseline diastolic BP (DBP).

Methods

We related baseline DBP with the SPRINT primary composite end point (myocardial infarction, acute coronary syndrome, stroke, acute decompensated heart failure, or cardiovascular death) and all-cause death. We examined the effect of intensive SBP lowering on these outcomes across the range of baseline DBPs using Cox regression with treatment by baseline DBP interaction terms.

Results

Among 2646 SPRINT participants with CKD, lower baseline DBP was associated with a higher adjusted hazard of the primary composite end point and all-cause death. For example, participants with baseline DBP of 61 mm Hg (mean baseline DBP in the lowest tertile) experienced a 37% (95% CI, 7% to 75%) higher hazard of the primary outcome relative to participants with baseline DBP of 75 mm Hg (mean baseline DBP for overall). The benefit of intensive SBP lowering was consistent across a range of baseline DBPs on rates of the primary composite end point (linear interaction P value =0.56) and all-cause death (linear interaction P value =0.20).

Conclusions

Among SPRINT participants with baseline CKD, lower DBP was associated with higher rates of the primary composite end point and all-cause death. However, DBP did not seem to modify the benefit of intensive SBP lowering on the primary composite end point or all-cause death. Our results suggest that lower DBP should not necessarily impede more intensive SBP lowering in patients with mild to moderate CKD.

Intensive vs Standard Blood Pressure Control in Adults 80 Years or Older: A Secondary Analysis of the Systolic Blood Pressure Intervention Trial

OBJECTIVES

To evaluate the effect of intensive systolic blood pressure (SBP) control in older adults with hypertension, considering cognitive and physical function.

DESIGN

Secondary analysis.

SETTING

Systolic Blood Pressure Intervention Trial (SPRINT) PARTICIPANTS: Adults 80 years or older.

INTERVENTION

Participants with hypertension but without diabetes (N = 1167) were randomized to an SBP target below 120 mm Hg (intensive treatment) vs a target below 140 mm Hg (standard treatment).

MEASUREMENTS

We measured the incidence of cardiovascular disease (CVD), mortality, changes in renal function, mild cognitive impairment (MCI), probable dementia, and serious adverse events. Gait speed was assessed via a 4-m walk test, and the Montreal Cognitive Assessment (MoCA) was used to quantify baseline cognitive function.

RESULTS

Intensive treatment led to significant reductions in cardiovascular events (hazard ratio [HR] = .66; 95% confidence interval [CI] = .49-.90), mortality (HR = .67; 95% CI = .48-.93), and MCI (HR = .70; 95% CI = .51-.96). There was a significant interaction (P < .001) whereby participants with higher baseline scores on the MoCA derived strong benefit from intensive treatment for a composite of CVD and mortality (HR = .40; 95% CI = .28-.57), with no appreciable benefit in participants with lower scores on the MoCA (HR = 1.33 = 95% CI = .87-2.03). There was no evidence of heterogeneity of treatment effects with respect to gait speed. Rates of acute kidney injury and declines of at least 30% in estimated glomerular filtration rate were increased in the intensive treatment group with no between-group differences in the rate of injurious falls.

CONCLUSION

In adults aged 80 years or older, intensive SBP control lowers the risk of major cardiovascular events, MCI, and death, with increased risk of changes to kidney function. The cardiovascular and mortality benefits of intensive SBP control may not extend to older adults with lower baseline cognitive function.

TRIAL REGISTRATION

Clinicaltrials.gov identifier: NCT01206062. J Am Geriatr Soc 68:496-504, 2020.