Combined association of albuminuria and cystatin C-based estimated GFR with mortality, coronary heart disease, and heart failure outcomes: the Atherosclerosis Risk in Communities (ARIC) Study

Cystatin C as Biomarker for the Evaluation of Renal Outcome in AL Amyloidosis

Cystatin C (CysC) has emerged as a novel and potentially more reliable biomarker for the estimation of glomerular filtration in the general population in patients with various conditions. In AL amyloidosis, the current renal staging system and renal response criteria are based on proteinuria and creatinine-based eGFR. We explored the prognostic role of CysC and of estimation of eGFR based on CysC-based equations in a cohort of 195 patients with newly diagnosed AL amyloidosis with renal involvement. Baseline CysC level was strongly and independently associated with progression to dialysis, and CysC levels ≥ 1.9 mg/L can be used in combination with the current renal staging system to identify patients with different risk of progression to dialysis among renal stages 2 and 3. eGFR based on CysC performed at least similarly to eGFR based on creatinine alone (by CKD-EPI race free formula) and the cutoff of 30 mL/min/1.73 m2 could better predict progression to dialysis at 2 years. At 6 months landmark, an increase in CysC by ≥ 1 mg/L was associated with higher risk of progression to dialysis (HR: 19.8, 95% CI 6.5-60.5, p < 0.001); a reduction of CysC based eGFR ≥ 30% was also associated with poor renal outcome, with a prognostic performance similar to current renal progression criteria. In conclusion, CysC provides prognostic information regarding the renal outcomes in patients with AL amyloidosis independently of the established biomarkers, but requires further validation.

Association of serum klotho level with albuminuria in middle‑aged and elderly participants without diabetes mellitus: a cross‑sectional study

BACKGROUND

The relationship between serum klotho level and albuminuria is unknown in middle-aged and elderly participants without diabetes mellitus (DM). Therefore, we will investigate the association between serum klotho level and albuminuria in middle-aged and elderly participants without DM.

METHODS

Participants (aged 40-79) were from the five continuous cycles (2007-2016) of the National Health and Nutrition Examination Survey (NHANES). Multiple logistic regression was performed to investigate the association between serum klotho level and albuminuria.

RESULTS

9217 participants were included in the present study. 47.6% of the participants were male. The average age of the overall participants was 56.3 years (40-79 years). Overall, 823 participants with albuminuria were identified. After adjusted confounders (age, gender, marital status, ethnicity, family income to poverty ratio, education, body mass index, smoke, charlson comorbidity index, hypertension, hyperlipidemia, angiotensin converting enzyme inhibitor/angiotonin receptor blocker, and estimated glomerular filtration rate), participants with a high serum klotho level had a decreased risk for albuminuria. Compared with the lowest serum klotho level (Tertile 1), participants in Tertile 2 (odds ratio [OR] 0.83, 95% CI 0.70-0.99, P = 0.044) and Tertile 3 (OR 0.76, 95% CI 0.63-0.91, P = 0.003) had a lower risk of albuminuria (P for trend = 0.002). The stratified analysis showed that serum klotho level was still negatively associated with albuminuria in the subgroups, and statistically significant interactions were not observed in the subgroups (all P values for interactions > 0.05, except for the hypertension subgroup).

CONCLUSIONS

In middle-aged and elderly participants without DM, a high serum klotho level is associated with a decreased risk of albuminuria. In the future, the mechanism of the interaction between klotho and albuminuria needs to be elucidated to find new treatment targets for individuals without DM who suffer from albuminuria.

Aortic Stenosis and Renal Function: A Bidirectional Mendelian Randomization Analysis

BACKGROUND

Large observational studies have demonstrated a clear inverse association between renal function and risk of aortic stenosis (AS). Whether this represents a causal, reverse causal or correlative relationship remains unclear. We investigated this using a bidirectional 2-sample Mendelian randomization approach.

METHODS AND RESULTS

We collected summary statistics for the primary analysis of chronic kidney disease (CKD) and AS from genome-wide association study meta-analyses including 480 698 and 653 867 participants, respectively. We collected further genome-wide association study summary statistics from up to 1 004 040 participants for sensitivity analyses involving estimated glomerular filtration rate (eGFR) derived from creatinine, eGFR derived from cystatin C, and serum urea nitrogen. Inverse-variance weighted was the primary analysis method, with weighted-median, weighted-mode, Mendelian randomization-Egger, and Mendelian randomization-Pleiotropy Residual Sum and Outlier as sensitivity analyses. We did not find evidence of a causal relationship between genetically predicted CKD liability as the exposure and AS as the outcome (odds ratio [OR], 0.94 per unit increase in log odds of genetic liability to CKD [95% CI, 0.85-1.04], P=0.26) nor robust evidence of AS liability as the exposure and CKD as the outcome (OR, 1.04 per unit increase in log odds of genetic liability to AS [95% CI, 0.97-1.12], P=0.30). The sensitivity analyses were neutral overall, as were the analyses using eGFR derived from creatinine, eGFR derived from cystatin C, and serum urea nitrogen. All positive controls demonstrated strong significant associations.

CONCLUSIONS

The present study did not find evidence of a substantial effect of genetically predicted renal impairment on risk of AS. This has important implications for research efforts that attempt to identify prevention and treatment targets for both CKD and AS.

Albuminuria, Forgotten No More: Underlining the Emerging Role in CardioRenal Crosstalk

Kidneys have an amazing ability to adapt to adverse situations, both acute and chronic. In the presence of injury, the kidney is able to activate mechanisms such as autoregulation or glomerular hyperfiltration to maintain the glomerular filtration rate (GFR). While these adaptive mechanisms can occur in physiological situations such as pregnancy or high protein intake, they can also occur as an early manifestation of diseases such as diabetes mellitus or as an adaptive response to nephron loss. Although over-activation of these mechanisms can lead to intraglomerular hypertension and albuminuria, other associated mechanisms related to the activation of inflammasome pathways, including endothelial and tubular damage, and the hemodynamic effects of increased activity of the renin-angiotensin-aldosterone system, among others, are recognized pathways for the development of albuminuria. While the role of albuminuria in the progression of chronic kidney disease (CKD) is well known, there is increasing evidence of its negative association with cardiovascular events. For example, the presence of albuminuria is associated with an increased likelihood of developing heart failure (HF), even in patients with normal GFR, and the role of albuminuria in atherosclerosis has recently been described. Albuminuria is associated with adverse outcomes such as mortality and HF hospitalization. On the other hand, it is increasingly known that the systemic effects of congestion are mainly preceded by increased central venous pressure and transmitted retrogradely to organs such as the liver or kidney. With regard to the latter, a new entity called congestive nephropathy is emerging, in which increased renal venous pressure can lead to albuminuria. Fortunately, the presence of albuminuria is modifiable and new treatments are now available to reverse this common risk factor in the cardiorenal interaction.

Heart Failure in Patients with Chronic Kidney Disease

The function of the kidney is tightly linked to the function of the heart. Dysfunction/disease of the kidney may initiate, accentuate, or precipitate of the cardiac dysfunction/disease and vice versa, contributing to a negative spiral. Further, the reciprocal association between the heart and the kidney may occur on top of other entities, usually diabetes, hypertension, and atherosclerosis, simultaneously affecting the two organs. Chronic kidney disease (CKD) can influence cardiac function through altered hemodynamics and salt and water retention, leading to venous congestion and therefore, not surprisingly, to heart failure (HF). Management of HF in CKD is challenging due to several factors, including complex interplays between these two conditions, the effect of kidney dysfunction on the metabolism of HF medications, the effect of HF medications on kidney function, and the high risk for anemia and hyperkalemia. As a result, in most HF trials, patients with severe renal impairment (i.e., eGFR 30 mL/min/1.73 m2 or less) are excluded. The present review discusses the epidemiology, pathophysiology, and current medical management in patients with HF developing in the context of CKD.

[The effect of kidney function on the optimization of medical therapy and on mortality in heart failure with reduced ejection fraction]

INTRODUCTION

Renal dysfunction is a main limiting factor of applying and up-titrating guideline-directed medical therapy (GDMT) among patients with heart failure with reduced ejection fraction (HFrEF).

OBJECTIVE

Our retrospective monocentric observational study aimed to analyse the application ratio of combined neurohormonal antagonist therapy (RASi: ACEI/ARB/ARNI + βB + MRA) and 12-month all-cause mortality differences in terms of renal dysfunction among HFrEF patients hospitalized for heart failure.

METHOD

We retrospectively analysed the cohort of consecutive HFrEF patients, hospitalized at the Heart Failure Unit of our tertiary cardiological centre in 2019-2021. The application ratio of discharge triple therapy (TT) in five groups established on admission eGFR parameters, representing severity of renal dysfunction (eGFR≥90, eGFR = 60-89, eGFR = 45-59, eGFR = 30-44, eGFR<30 ml/min/1.73 m2) was investigated with chi-square test, while 12-month mortality differences were analysed with Kaplan-Meier method and log-rank test.

RESULTS

257 patients were included. Median eGFR was 57 (39-75) ml/min/1.73 m2, 54% of patients had eGFR<60 ml/min/1.73 m2. The proportion of patients in eGFR≥90, 60-89, 45-59, 30-44, <30 ml/min/1.73 m2 subgroups was 12%, 34%, 18%, 21%, 15%, respectively. 2% of patients were on dialysis. Even though the application rate of TT was notably high (77%) in the total cohort, more severe renal dysfunction led to a significantly lower implementation rate of TT (94%, 86%, 91%, 70%, 34%; p<0.0001): the application rate of RASi (100%, 98%, 96%, 89%, 50%, p<0.0001), βB (94%, 88%, 96%, 79%, 68%; p = 0.003) and MRA therapy (97%, 99%, 98%, 94%, 82%; p = 0.001) differed significantly. 12-month all-cause mortality was 23% in the whole cohort. Mortality rates were higher in more severe renal dysfunction (3%, 15%, 22%, 31%, 46%; p<0.0001).

CONCLUSION

Even though the proportion of patients on TT in the whole cohort was remarkably high, renal dysfunction led to a significantly lower application ratio of TT, associating with worse survival. Our results highlight that despite renal dysfunction the application of HFrEF cornerstone pharmacotherapy is essential. Orv Hetil. 2023; 164(35): 1387-1396.

Longitudinal changes in blood pressure are preceded by changes in albuminuria and accelerated by increasing dietary sodium intake

BACKGROUND

Dietary sodium is a well-known risk factor for cardiovascular and renal disease; however, direct evidence of the longitudinal changes that occur with aging, and the influence of dietary sodium on the age-associated alterations are scarce.

METHODS

C57BL/6 mice were maintained for 13 months on a low (LS, 0.02 % Na+), normal (NS, 0.3 % Na+) or high (HS, 1.6 % Na+) salt diet. We assessed 1) the longitudinal trajectories for two markers of cardiovascular and renal dysfunction (blood pressure (BP) and albuminuria), as well as hormonal changes, and 2) end-of-study cardiac and renal parameters.

RESULTS

The effect of aging on BP and kidney damage did not reach significance levels in the LS group; however, relative to baseline, there were significant increases in these parameters for animals maintained on NS and HS diets, starting as early as month 7 and month 5, respectively. Furthermore, changes in albuminuria preceded the changes in BP relative to baseline, irrespective of the diet. Circulating aldosterone and plasma renin activity displayed the expected decreasing trends with age and dietary sodium loading. As compared to LS - higher dietary sodium consumption associated with increasing trends in left ventricular mass and volume indices, consistent with an eccentric dilated phenotype. Functional and molecular markers of kidney dysfunction displayed similar trends with increasing long-term sodium levels: higher renovascular resistance, increased glomerular volumes, as well as higher levels of renal angiotensin II type 1 and mineralocorticoid receptors, and lower renal Klotho levels.

CONCLUSION

Our study provides a timeline for the development of cardiorenal dysfunction with aging, and documents that increasing dietary salt accelerates the age-induced phenotypes. In addition, we propose albuminuria as a prognostic biomarker for the future development of hypertension. Last, we identified functional and molecular markers of renal dysfunction that associate with long-term dietary salt loading.

Glycemia is associated with subclinical atherosclerosis through renal function in nondiabetic apparently healthy adults: a mediation analysis

The causative associations between glycemia and early alterations in renal and vascular function remain unclear. To examine the interplay among glycemia, renal function, and markers of subclinical atherosclerosis in apparently healthy subjects. Nondiabetic (30-60 years old) individuals (n = 205) without chronic kidney disease or cardiovascular disease were consecutively recruited from a cardiovascular prevention clinic. All subjects underwent arterial stiffness assessment by measuring the carotid-femoral pulse wave velocity (cfPWV). Glomerular filtration rate (GFR) was estimated by CKD-EPI equation. Study procedures were identical in the two visits (median follow-up 66 months). We employed structural equation modeling (SEM) analysis to investigate the directionality of associations. Baseline fasting plasma glucose (FPG) was independently and inversely associated with GFR (p = 0.008). GFR was significantly associated with cfPWV (p < 0.001) at baseline. By SEM analysis decreasing baseline GFR directly correlated with increasing cfPWV (p = 0.003) whereas FPG correlated with cfPWV indirectly through GFR (mediation) (P = 0.032). FPG did not mediate the effect of GFR on cfPWV (P = 0.768). SEM analysis of longitudinal data revealed bidirectional correlations between changes in FPG and GFR (P < 0.001). Alterations in GFR were directly related to changes in cfPWV (p < 0.001) whereas FPG only indirectly correlated with cfPWV through GFR changes (P = 0.002). In apparently healthy nondiabetic subjects, the association between baseline or longitudinal glycemia levels and arterial stiffening was indirect, consistently mediated by renal function status. These findings provide the first clinical evidence supporting the directionality between kidney function and glycemia in nondiabetic subjects leading to vascular dysfunction. In apparently healthy nondiabetic subjects, without cardiovascular disease or chronic kidney disease, the association between baseline or longitudinal glycemia levels and arterial stiffening was indirect, consistently mediated by renal function status.

Physical Function and Subsequent Risk of Cardiovascular Events in Older Adults: The Atherosclerosis Risk in Communities Study

Background

Reduced physical function, a representative phenotype of aging, has been associated with cardiovascular disease (CVD). However, few studies have comprehensively investigated its association with composite and individual CVD outcomes in community‐dwelling older adults and its predictive value for CVD beyond traditional risk factors.

Methods and Results

We studied 5570 participants (mean age 75 [SD 5] years, female 58%, Black 22%) at visit 5 (2011–2013) of the ARIC (Atherosclerosis Risk in Communities) study. Physical function was evaluated with the Short Physical Performance Battery (SPPB), which incorporates a walk test, chair stands, and balance tests. The SPPB score was modeled categorically (low [0–6], intermediate [7–9], and high [10–12]) and continuously. We assessed the associations of SPPB score with subsequent composite (coronary heart disease, stroke, or heart failure) and individual CVD outcomes (components within composite outcome) using multivariable Cox models adjusting for major CVD risk factors and history of CVD. We also evaluated improvement in C‐statistics by adding SPPB to traditional CVD risk factors in the Pooled Cohort Equation. Among the study participants, 13% had low, 30% intermediate, and 57% high SPPB scores. During a median follow‐up of 7.0 (interquartile interval 5.3–7.8) years, there were 930 composite CVD events (386 coronary heart disease, 251 stroke, and 529 heart failure cases). The hazard ratios of composite CVD in low and intermediate versus high SPPB score were 1.47 (95% CI, 1.20–1.79) and 1.25 (95% CI, 1.07–1.46), respectively, after adjusting for potential confounders. Continuous SPPB score demonstrated independent associations with each CVD outcome. The associations were largely consistent across subgroups (including participants with prevalent CVD at baseline). The addition of SPPB to traditional CVD risk factors significantly improved the C‐statistics of CVD outcomes (eg, ΔC‐statistic 0.019 [95% CI, 0.011–0.027] for composite CVD).

Conclusions

Reduced physical function was independently associated with the risk of composite and individual CVD outcomes and improved their risk prediction beyond traditional risk factors in community‐dwelling older adults. Although confirmatory studies are needed, our results suggest the potential usefulness of SPPB for classifying CVD risk in older adults.

Can chronic kidney disease lead to chronic heart failure, and does worsening chronic heart failure lead to chronic kidney disease progression

PURPOSE OF REVIEW

The objective of this review is to discuss if chronic kidney disease (CKD) leads to chronic heart failure (CHF), and does worsening CHF lead to CKD progression and how a new medication class can modify the risk of both outcomes.

RECENT FINDINGS

Sodium-glucose cotransporter 2 (SGLT2) inhibitors are similarly effective on cardiovascular (CV) - and kidney-related outcomes in the presence of CV and CKD.

SUMMARY

SGLT2 inhibitors can reduce the risk of CHF events and CKD progression, and may have synergistic effects in patients with cardiorenal syndrome.

Synergistic association of the copper/zinc ratio under inflammatory conditions with diabetic kidney disease in patients with type 2 diabetes: The Asahi Diabetes Complications Study

AIMS/INTRODUCTION

We aimed to study the relationships among the copper (Cu)/zinc (Zn) ratio, inflammatory biomarkers, and the prevalence of diabetic kidney disease (DKD) in patients with type 2 diabetes.

MATERIALS AND METHODS

A cross-sectional study was performed on 651 patients with type 2 diabetes. DKD was defined as a urinary albumin-to-creatinine ratio of ≥30 mg/g creatinine and/or an estimated glomerular filtration rate using cystatin C of < 60 mL/min/1.73 m2 . Areas under the curves (AUCs), cutoff values, and thresholds for detecting DKD were determined for the Cu/Zn ratio, soluble tumor necrosis factor-α receptor 1 (sTNFαR1), and high-sensitivity C-reactive protein (hsCRP). Patients were categorized by each cutoff value of sTNFαR1 and the Cu/Zn ratio. Odds ratios (ORs) and biological interactions for the prevalence of DKD were determined.

RESULTS

DKD was identified in 220 patients. AUC/optimal cutoff values were 0.777/1300 pg/mL for sTNFαR1, 0.603/1.1648 for the Cu/Zn ratio, and 0.582/305 ng/mL for hsCRP. The ORs for DKD were higher, but not significantly, in the sTNFαR1 < 1300 and Cu/Zn ≥ 1.1648 group, significantly higher in the sTNFαR1 ≥ 1300 and Cu/Zn < 1.1648 group (P < 0.0001), and further synergistically elevated in the sTNFαR1 ≥ 1300 and Cu/Zn ≥ 1.1648 group (P < 0.0001) compared with the sTNFαR1 < 1300 and Cu/Zn < 1.1648 group after multivariable adjustment. Levels of sTNFαR1 were significantly higher in the sTNFαR1 ≥ 1300 and Cu/Zn ≥ 1.1648 group than in the sTNFαR1 ≥ 1300 and Cu/Zn < 1.1648 group (P = 0.0006).

CONCLUSIONS

Under an inflammatory initiation signal of elevated serum sTNFαR1 levels, an increase in the Cu/Zn ratio may further exacerbate inflammation and is synergistically associated with a high prevalence of DKD in patients with type 2 diabetes.

Albuminuria within the Normal Range Can Predict All-Cause Mortality and Cardiovascular Mortality

BACKGROUND

Despite interest in low-grade albuminuria and poor clinical outcomes, evidence from a large-scale population is lacking. Therefore, we identified the association of low-grade albuminuria within the normal range with all-cause and cardiovascular (CV) mortality.

METHODS

After excluding individuals with urine albumin-creatinine ratio (ACR) ≥30 mg/g (n=6094), this cohort study analyzed 43,396 adults who participated in the National Health and Nutrition Examination Survey (1999-2016). Participants were divided into four quartiles of ACR. The primary outcome was all-cause mortality, and the secondary outcome was CV mortality. Multivariable Cox proportional hazards models were used.

RESULTS

During a median 7.9 years of follow-up, 3516 (9%) participants died. Compared with the reference group (Q1, ACR <4.171 mg/g), low-grade albuminuria groups were associated with all-cause mortality (Q3, ACR ≥6.211 to <10.010 mg/g, hazard ratio [HR], 1.25 [95% CI, 1.11 to 1.41]; Q4, ACR ≥10.010 mg/g, HR, 1.57 [95% CI, 1.41 to 1.76]) in a multivariable hazards model. A similar pattern was also seen in the association of low-grade albuminuria with CV mortality. Subgroup analyses showed that low-grade albuminuria was also associated with all-cause mortality in the nondiabetic group, nonhypertensive group, and non-CKD group (eGFR ≥60 ml/min per 1.73 m²).

CONCLUSIONS

Our findings suggest that low-grade albuminuria is associated with all-cause and CV mortality. Low-grade albuminuria should be monitored, even for patients with low CV risk.

Time-Updated Changes in Estimated GFR and Proteinuria and Major Adverse Cardiac Events: Findings from the Chronic Renal Insufficiency Cohort (CRIC) Study

RATIONALE & OBJECTIVE

Evaluating repeated measures of estimated glomerular filtration rate (eGFR) and urinary protein-creatinine ratio (UPCR) over time may enhance our ability to understand the association between changes in kidney parameters and cardiovascular disease risk.

STUDY DESIGN

Prospective cohort study.

SETTING & PARTICIPANTS

Annual visit data from 2,438 participants in the Chronic Renal Insufficiency Cohort (CRIC).

EXPOSURES

Average and slope of eGFR and UPCR in time-updated, 1-year exposure windows.

OUTCOMES

Incident heart failure, atherosclerotic cardiovascular disease events, death, and a composite of incident heart failure, atherosclerotic cardiovascular disease events, and death.

ANALYTICAL APPROACH

A landmark analysis, a dynamic approach to survival modeling that leverages longitudinal, iterative profiles of laboratory and clinical information to assess the time-updated 3-year risk of adverse cardiovascular outcomes.

RESULTS

Adjusting for baseline and time-updated covariates, every standard deviation lower mean eGFR (19mL/min/1.73m²) and declining slope of eGFR (8mL/min/1.73m² per year) were independently associated with higher risks of heart failure (hazard ratios [HRs] of 1.82 [95% CI, 1.39-2.44] and 1.28 [95% CI, 1.12-1.45], respectively) and the composite outcome (HRs of 1.32 [95% CI, 1.11-1.54] and 1.11 [95% CI, 1.03-1.20], respectively). Every standard deviation higher mean UPCR (136mg/g) and increasing UPCR (240mg/g per year) were also independently associated with higher risks of heart failure (HRs of 1.58 [95% CI, 1.28-1.97] and 1.20 [95% CI, 1.10-1.29], respectively) and the composite outcome (HRs of 1.33 [95% CI, 1.17-1.50] and 1.12 [95% CI, 1.06-1.18], respectively).

LIMITATIONS

Limited generalizability of annual eGFR and UPCR assessments; several biomarkers for cardiovascular disease risk were not available annually.

CONCLUSIONS

Using the landmark approach to account for time-updated patterns of kidney function, average and slope of eGFR and proteinuria were independently associated with 3-year cardiovascular risk. Short-term changes in kidney function provide information about cardiovascular risk incremental to level of kidney function, representing possible opportunities for more effective management of patients with chronic kidney disease.

The unmet need of evidence-based therapy for patients with advanced chronic kidney disease and heart failure: Position paper from the Cardiorenal Working Groups of the Spanish Society of Nephrology and the Spanish Society of Cardiology

Despite the high prevalence of chronic kidney disease (CKD) and its high cardiovascular risk, patients with CKD, especially those with advanced CKD (stages 4-5 and patients on kidney replacement therapy), are excluded from most cardiovascular clinical trials. It is particularly relevant in patients with advanced CKD and heart failure (HF) who have been underrepresented in many pivotal randomized trials that have modified the management of HF. For this reason, there is little or no direct evidence for HF therapies in patients with advanced CKD and treatment is extrapolated from patients without CKD or patients with earlier CKD stages. The major consequence of the lack of direct evidence is the under-prescription of HF drugs to this patient population. As patients with advanced CKD and HF represent probably the highest cardiovascular risk population, the exclusion of these patients from HF trials is a serious deontological fault that must be solved. There is an urgent need to generate evidence on how to treat HF in patients with advanced CKD. This article briefly reviews the management challenges posed by HF in patients with CKD and proposes a road map to address them.

Discordance between the triglyceride glucose index and HOMA-IR in incident albuminuria: a cohort study from China

Background

To date, there have no study comparing the associations between TyG index and HOMA-IR on the risk of incident albuminuria. Accordingly, the objective of the present study is to use discordance analysis to evaluate the diverse associations between TyG index and HOMA-IR on the risk of incident albuminuria.

Methods

A community-based prospective cohort study was performed with 2446 Chinese adults. We categorized participants into 4 concordance or discordance groups. Discordance was defined as a TyG index equal to or greater than the upper quartile and HOMA-IR less than the upper quartile, or vice versa.

Results

During a median follow-up period of 3.9 years, 203 of 2446 participants developed incident albuminuria (8.3%). In the multivariable logistic analyses, the high TyG index tertile group was associated with a 1.71-fold (95% confidence interval (CI) 1.07–2.72) higher risk of incident albuminuria, comparing with the low tertile group. Participants in TyG (+) & HOMA-IR (−) group had a greater risk of incident albuminuria compared with those in TyG (−) & HOMA-IR (−) group after multivariate adjustment. Subgroup analyses showed that low HOMA-IR and discordantly high TyG index was closely related to a highest risk of incident albuminuria in cardiovascular metabolic disorder subjects.

Conclusions

Participants with a discordantly high TyG index had a significantly greater risk of incident albuminuria, especially in metabolic dysfunction subjects. The TyG index might be a better predictor of early stage of chronic kidney disease than HOMA-IR for subjects with metabolic abnormality.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12944-021-01602-w.

Successful Treatment of Severe Heart Failure in Advanced Diabetic Kidney Disease Using Angiotensin-neprilysin Inhibitors (Sacubitril/Valsartan) - Report of Two Cases with Review of Options in Literature

Patients with heart failure (HF) and advanced chronic kidney disease (CKD) constitute a special population that experience poor outcomes due to poor adherence to established therapies because of potential safety concerns. Role of newer agents like angiotensin–receptor neprilysin inhibitors (ARNI) in early stages of CKD is well elucidated. We report two cases of HF with reduced ejection fraction, who received ARNI in advanced stage of CKD (stage 5) and achieved remarkable outcomes in terms of quality of life and longevity.

Refocusing on the Primary Prevention of Heart Failure

Purpose of review

The burden of heart failure (HF) is a significant national and global public health problem, with prevalence rates on the rise. Given the significant morbidity, mortality, and healthcare costs attributable to HF, it is of utmost importance to utilize preventive strategies to prevent the development of HF. Therefore, we sought to address how a multi-modal risk assessment approach can be used to stratify patients for HF risk and guide implementation of therapeutic strategies to prevent HF.

Recent findings

New externally validated, multivariate prediction models for incident HF can be applied in the general population and may be used to aide clinicians in assessing individualized HF risk and screening for HF. Recent clinical trial data suggest a natriuretic peptide biomarker-based screening approach coupled with team-based cardiovascular care to focus on optimization of guideline-directed medical therapy may help prevent new-onset HF. However, widespread implementation of clinical risk scores and/or biomarkers is needed.

Summary

In addition to promoting a heart healthy lifestyle, prevention and management of modifiable risk factors, including intensive blood pressure lowering and use of sodium-glucose cotransporter-2 inhibitors, can prevent incident HF.

Prognostic value of cystatin C in patients with acute coronary syndrome: A systematic review and meta-analysis

BACKGROUND

Circulating cystatin C has been considered as an independent predictor of cardiovascular and all-cause mortality in the general population. The purpose of this study was to evaluate the prognostic value of baseline circulating cystatin C levels in patients with acute coronary syndrome (ACS) through meta-analysis.

METHODS

Prospective studies about the relationship between the level of cystatin C and the prognosis of ACS patients were searched on PubMed, Web of science, Cochrane Library and Embase databases from the establishment of the databases to July 2020. The prognostic values included in this analysis covered all-cause mortality, major adverse cardiovascular events (MACE) and recurrent myocardial infarction. The effect index between cystatin C level and ACS risk was carried out by hazard ratio (HR). Stata 15.0 software was used for statistical analysis. The quality of the included literature was evaluated according to Newcastle-Ottawa Scale (NOS).

RESULTS

A total of 10 studies were included in this meta-analysis. The results showed that high cystatin C levels significantly predicted the all-cause mortality of ACS, HR = 2.53 (95%CI: 1.72 ~ 3.72). High cystatin C level significantly predicted MACE of patients with ACS, HR = 3.24 (95%CI: 1.30 ~ 8.07). However, it had no significant predictive significance for recurrent myocardial infarction, HR = 1.71 (95%CI:0.99 ~ 2.97).

CONCLUSION

Our meta-analysis showed that high cystatin C levels were significantly associated with the death risk and MACE in ACS patients. Therefore, cystatin C can be included in the risk stratification model to guide the treatment of high-risk ACS patients.

Burden of Chronic Kidney Disease by KDIGO Categories of Glomerular Filtration Rate and Albuminuria: A Systematic Review

INTRODUCTION

The Kidney Disease: Improving Global Outcomes (KDIGO) 2012 guidelines recommend classifying patients by glomerular filtration rate (GFR) and albuminuria to predict chronic kidney disease (CKD) prognosis. The aim of this systematic review was to explore the epidemiological burden of CKD stratified by the KDIGO 2012 categories.

METHODS

MEDLINE® and Embase were searched for observational studies of patients with CKD with results stratified according to the KDIGO 2012 classification. Investigated outcomes were prevalence, incidence, and risk factors and complications of CKD, including mortality.

RESULTS

The review included ten observational studies with 3033 to 46,949 participants, conducted in the USA, China, France, Italy and Spain. The most frequently reported outcome was the prevalence of CKD (GFR categories G3-5), ranging from 2% to 17%. Most participants were normoalbuminuric, with 0.4-3.2% macroalbuminuric, and most fell within the KDIGO 2012 low-risk or moderate-risk groups, with 0.9-5.6% in the high-risk and 0.3-4.8% in the very high-risk groups. Although scarce, data on the prevalence of comorbidities in CKD according to the KDIGO classification suggest that they increase with albuminuria severity.

CONCLUSIONS

Patients with CKD frequently have complications, but only a small proportion have severely increased albuminuria or fall within the KDIGO high-risk or very high-risk groups. These groups, however, are associated with the highest burden of disease, as comorbidities are more prevalent with increasing albuminuria severity. New studies framed by the KDIGO 2012 classification are needed to address key gaps in the understanding of CKD burden and outcomes.

GFR Estimation After Cystatin C Reference Material Change

Introduction

Glomerular filtration rate (GFR) is routinely estimated with cystatin C. In June 2010, the International Federation of Clinical Chemistry (IFCC) released a certified cystatin C reference material (ERM-DA471/IFCC), and new cystatin C glomerular filtration rate estimation (eGFR) equations were developed with the IFCC standard. Early in 2018, Siemens discontinued their nonstandardized cystatin C reagent kits and replaced them with IFCC-calibrated kits in the US market. The aim of the current study was to assess the effect of IFCC calibration on cystatin C values and corresponding GFR estimations.

Methods

Cystatin C concentration was measured in 81 pediatric patients using a plasma sample from their nuclear GFR measurement with 99mTc-diethylenetriaminepentaaccetic acid. Calibration curves were generated using Siemens nonstandardized and IFCC-standardized kits to measure paired cystatin C concentrations in each sample. GFR-estimating equations using pre-IFCC and IFCC cystatin C values were compared using Bland-Altman analyses.

Results

The IFCC-standardized assay resulted in a mean increase in the measured cystatin C value of 24%. Estimating equations consistently overestimated GFR prior to IFCC standardization. Following incorporation of the IFCC standard, the Full Age Spectrum equation demonstrated the best overall performance, whereas the Chronic Kidney Disease in Children (CKiD) equation was more accurate in children with decreased GFR.

Conclusion

Incorporation of the IFCC standard significantly increased cystatin C values and affected the performance of GFR estimating equations. Clinical laboratories and providers may need to update the equation used for cystatin C-based estimation of GFR following adoption of the IFCC reference standard.

Kidney Function as Risk Factor and Predictor of Cardiovascular Outcomes and Mortality Among Older Adults

RATIONALE & OBJECTIVE

Estimated glomerular filtration rate (eGFR) and urinary albumin-creatinine ratio (UACR) are associated with cardiovascular events in the general population but their utility among older adults is unclear. We investigated the associations of eGFR and UACR with stroke, myocardial infarction (MI), and death among older adults.

STUDY DESIGN

Population-based cohort study.

SETTING & PARTICIPANTS

1,581 participants (aged≥70 years) in the Berlin Initiative Study (BIS) without prior stroke or MI.

EXPOSURES & PREDICTORS

Serum creatinine- and cystatin C-based eGFR, UACR categories, and measured GFR (n=436).

OUTCOMES

Stroke, MI, and all-cause mortality.

ANALYTICAL APPROACH

HRs and 95% CIs derived from multivariable-adjusted Cox proportional hazards models for association analyses. Net reclassification improvement (NRI) and C statistic differences comparing the predictive benefit of kidney measures with a traditional cardiovascular risk model.

RESULTS

During a median follow-up of 8.2 years, 193 strokes, 125 MIs, and 531 deaths occurred. Independent of UACR, when GFR was estimated using the creatinine- and cystatin C-based BIS equation, eGFR of 45 to 59mL/min/1.73m² (vs eGFR>60mL/min/1.73m²) was associated with stroke (HR, 2.23; 95% CI, 1.55-3.21) but not MI or all-cause mortality. For those with eGFR<45mL/min/1.73m², the HRs were 1.99 (95% CI, 1.23-3.20) for stroke, 1.38 (95% CI, 0.81-2.36) for MI, and 1.57 (95% CI, 1.20-2.06) for mortality. Compared with UACR<30mg/g, UACR of 30 to 300mg/g was not associated with stroke (HR, 0.91; 95% CI, 0.63-1.33) but was associated with MI (HR, 1.65; 95% CI, 1.09-2.51) and all-cause mortality (HR, 1.63; 95% CI, 1.34-1.98). Prediction analysis for stroke showed significant positive NRI for eGFR calculated using the cystatin C-based Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equation and the creatinine- and cystatin C-based BIS and Full Age Spectrum equations. UACR demonstrated significant positive NRIs for MI and mortality.

LIMITATIONS

eGFR and UACR categorization based on single assessments; lack of cause-specific death data.

CONCLUSIONS

eGFR of 45 to 59mL/min/1.73m² without albuminuria was associated with stroke but not MI or all-cause mortality in older adults. In contrast, UACR of 30 to 300mg/g was associated with MI and all-cause mortality but not with stroke. Furthermore, cystatin C-based eGFR improved risk prediction for stroke in this cohort of older adults.

Cystatin C-based estimated GFR and albuminuria are independently associated with all-cause and CVD mortality in Korean population: The Dong-gu Study

OBJECTIVE

To assess the associations among the estimated glomerular filtration rate (eGFR), albumin to creatinine ratio (ACR), and all-cause and CVD mortality rate and to compare the performances of eGFR_MDRD, eGFR_CKD-EPI, and eGFR_cys using receiver operating characteristic (ROC) analysis in Korean adults aged ≥ 50 years.

METHODS

Of the 9,260 subjects who participated in the baseline survey of a prospective longitudinal study conducted in Korea, 9,009 (men: 3,574 (39.7%); women: 5,435 (60.3%)) were included in this analysis after the exclusion of 217 subjects with missing eGFR and 34 subjects with missing ACR data.

MAIN OUTCOME MEASURE

The associations of eGFR and ACR with all-cause and CVD mortality were investigated using Cox proportional hazards models that included sex, age, waist circumference, smoking, alcohol intake, degree of physical activity, hypertension, diabetes, systolic blood pressure, log-HbA_1c, total cholesterol, log-triglyceride, log-HDL and log-ACR or eGFR.

RESULTS

After adjustment for covariates, independent associations were found between all-cause mortality and the eGFR_cys (mL/min per 1.73 m²) [HR 1.23, 95% confidence interval (CI) 1.05-1.43 for 60-89 vs. ≥ 90; HR 1.87, 95% CI 1.49-2.34 for 45-59 vs. ≥ 90; HR 2.38, 95% CI 1.77-3.20 for 30-44 vs. ≥ 90; HR 2.82, 95% CI 1.89-4.23 for <30 vs. ≥ 90] and ACR (μg/mg creatinine) [HR 1.09, 95% CI 0.88-1.34 for Q2 vs. Q1; HR 1.34, 95% CI 1.10-1.63 for Q3 vs. Q1; HR 1.49, 95% CI 1.22-1.81 for Q4 vs. Q1]. In addition, independent associations of CVD mortality with the eGFR_cys and ACR were significant. In the comparison of eGFR performance, the ROC-plot AUC for all-cause mortality was significantly greater for the eGFR_cys than for the eGFR_MDRD and eGFR_CKD-EPI.

CONCLUSION

The eGFR_cys and ACR were associated independently with all-cause and CVD mortality after adjustment for covariates, including the eGFR_cys and ACR. In addition, the ROC-plot AUC for all-cause mortality was greater for the eGFR_cys than for the eGFR_MDRD and eGFR_CKD-EPI in Korean adults aged ≥ 50 years.

Association of Urine Albumin Excretion With Incident Heart Failure Hospitalization in Community-Dwelling Adults

OBJECTIVES

This study examined the association between urinary albumin excretion and incident heart failure (HF) hospitalization.

BACKGROUND

Excess urinary albumin excretion is more strongly associated with incident stroke and coronary heart disease risk in black than in white individuals. Whether similar associations extend to HF is unclear.

METHODS

This study examined the associations between the urinary albumin-to-creatinine ratio (ACR) and incident hospitalization for HF overall in 24,433 REGARDS (Reasons for Geographic and Racial Differences in Stroke) study participants free of suspected HF at baseline; findings were stratified by race and HF subtype (preserved vs. reduced ejection fraction). Models were adjusted for sociodemographic, clinical, and laboratory variables including estimated glomerular filtration rate, and multiple imputation was used to account for missing covariate data.

RESULTS

After a median follow-up of 9.2 years, 881 incident HF events (332 preserved ejection fraction, 447 reduced ejection fraction, 102 unspecified) were observed. Compared to the lowest ACR category (<10 mg/g), the risk of incident HF increased with increasing ACR categories (10 to 29 mg/g hazard ratio [HR]: 1.49; 95% confidence interval [CI]: 1.26 to 1.78; 30 to 300 mg/g HR: 2.32; 95% CI: 1.93 to 2.78; >300 mg/g HR: 4.42; 95% CI: 3.36 to 5.83) in the fully adjusted model. Results did not differ by race. The magnitude of the association between ACR and HF with preserved ejection fraction was greater than with HF with reduced ejection fraction (HR comparing highest vs. lowest ACR category: 6.20; 95% CI: 4.15 to 9.26 vs. HR: 4.37; 95% CI: 3.00 to 6.25, respectively; p = 0.05).

CONCLUSIONS

Higher ACR was associated with greater risk of incident HF hospitalization in community-dwelling black and white adults.

Kidney Disease Biomarkers Improve Heart Failure Risk Prediction in the General Population

BACKGROUND

The kidneys play an important role in heart failure (HF), but it is unclear if renal biomarkers improve HF risk prediction beyond established risk factors. We aimed to assess whether adding biomarkers of kidney disease to conventional risk factors improved 10-year risk prediction for incident HF in a contemporary community sample.

METHODS

We included 450 212 participants in the UK Biobank aged 39 to 70 years without HF who had been assessed in 2006 to 2010 with the urine albumin-to-creatinine ratio and estimated glomerular filtration rate (eGFR) based on serum creatinine and cystatin C. There were 1701 incident cases of HF during up to 10.3 years of follow-up (mean 8.2±0.7 years). We used the Atherosclerosis Risk in Communities study heart failure risk score excluding natriuretic peptides as the base model to which we added eGFR and urine albumin-to-creatinine ratio. Harrell's C-statistic of ARIC-HF was 0.845 (95% CI, 0.831-0.859).

RESULTS

Each combination of added kidney measures (creat-eGFR, cysC-eGFR, and urine albumin-to-creatinine ratio) led to significant improvement in risk discrimination, calibration, and reclassification. The optimal pair of added kidney measures was cysC-eGFR and urine albumin-to-creatinine ratio (ΔC=0.019 [95% CI, 0.015-0.022]). Addition of cysC-eGFR made the largest contribution to reclassification improvement (continuous net reclassification improvement 0.323 [95% CI, 0.278-0.360]).

CONCLUSIONS

In a large community sample, the addition of kidney disease markers to conventional risk factors improved prediction of 10-year HF risk. Our results support including kidney disease markers in the identification of persons at highest risk of HF and demonstrate a possible role of impaired kidney function in HF development in asymptomatic persons.

Serum Levels of Cystatin C, N-Terminal Pro-B-Type Natriuretic Peptide (NT-proBNP), and Cardiac Function in Patients with Unstable Angina Pectoris

Background

This study aimed to investigate the association between serum levels of cystatin C, N-terminal pro-B-type natriuretic peptide (NT-proBNP), and cardiac function in patients with unstable angina pectoris (UAP).

Material/Methods

A cross-sectional observational study was conducted at a single center and recruited 300 patients (214 men and 86 women), who were diagnosed with UAP between June 2018 to December 2018. The patients had serum levels of NT-ProBNP measured and were divided into four groups according to the serum levels of cystatin C: Q1, 0.49–0.83 mg/L; Q2, 0.84–1.04 mg/L; Q3, 1.05–1.38 mg/L; Q4, 1.39–4.21 mg/L. Cardiac function was graded according to the New York Heart Association (NYHA) class I to IV criteria.

Results

In the 300 patients with UAP, there were significant differences in cardiac function and NT-ProBNP levels between the four study groups (Q1 to Q4) (p<0.05). Univariate analysis showed that body weight, heart rate, treatment with aspirin, ticagrelor, angiotensin-converting enzyme inhibitor and an angiotensin receptor blocker (ACE/ARB), diuretic use, uric acid level, and serum cystatin C levels were significantly associated with increased levels of NT-ProBNP. After adjusting for confounding factors screened in univariate analysis, multivariate regression analysis showed that increased serum cystatin C levels were significantly associated with increased levels of NT-ProBNP.

Conclusions

Increased serum levels of cystatin C were associated with poor cardiac function and increased levels of NT-ProBNP in patients with UAP.

Diagnostic performance of serum cystatin C and complement component 1q in lupus nephritis

BACKGROUND

The information concerning non-invasive, easily obtainable, and accurate biomarkers for diagnosis of lupus nephritis (LN) is extremely limited. The aim of this study was to evaluate the diagnostic performance of cystatin C (CysC) and complement component 1q (C1q) for LN.

METHODS

A case-control study that included 905 patients with systemic lupus erythematosus (SLE) without LN (group SLE), 334 patients with active lupus nephritis (group LNA), 255 patients with inactive lupus nephritis (group LNI), and 497 healthy individuals (group HC) was performed in Mianyang Central Hospital from March 2017 to December 2018. The serum levels of CysC, C1q, urea (Urea), and creatinine (Creat) were measured, and 2 estimated glomerular filtration rates (eGFRCysC and eGFRCreat) were calculated by equations which were based on serum CysC established by our group and the modification of diet in renal disease (MDRD), respectively. ANOVA analysis or Kruskal-Wallis test was used for comparing the differences among the groups, and receiver operating characteristic (ROC) curve was applied to identify the diagnostic efficiencies of individual or combined multiple indicators.

RESULTS

Significantly elevated CysC and decreased C1q were observed in the LNA and LNI groups, which was in contrast to their levels in the SLE and HC groups. CysC (AUC = 0.906) or eGFRCysC (AUC = 0.907) assessed the highest diagnostic performance on LNA when detected individually, followed by C1q (AUC = 0.753). Joint utilization of C1q and CysC achieved very good performance (AUC = 0.933) which approximated to the best one observed in the combinations of C1q, Urea, CysC, eGFRCreat, and Creat (AUC = 0.975).

CONCLUSION

The separately detected CysC (eGFRCysC) and C1q were superior to the conventional biomarkers Urea, Creat, and eGFRCreat in the diagnosis of LNA. Moreover, although the combined detection of Urea, Creat, C1q, CysC, and eGFRCreat had the greatest diagnostic performance, the joint utilization of CysC and C1q could be prioritized for rapid discrimination of LNA if the economic burden is taken into consideration.

Refining the Mouse Subtotal Nephrectomy in Male 129S2/SV Mice for Consistent Modeling of Progressive Kidney Disease With Renal Inflammation and Cardiac Dysfunction

Chronic kidney disease (CKD) is prevalent worldwide and is associated with significant co-morbidities including cardiovascular disease (CVD). Traditionally, the subtotal nephrectomy (remnant kidney) experimental model has been performed in rats to model progressive renal disease. The model experimentally mimics CKD by reducing nephron number, resulting in renal insufficiency. Presently, there is a lack of translation of pre-clinical findings into successful clinical results. The pre-clinical nephrology field would benefit from reproducible progressive renal disease models in mice in order to avail of more widely available transgenics and experimental tools to dissect mechanisms of disease. Here we evaluate if a simplified single step subtotal nephrectomy (STNx) model performed in the 129S2/SV mouse can recapitulate the renal and cardiac changes observed in patients with CKD in a reproducible and robust way. The single step STNx surgery was well-tolerated and resulted in clinically relevant outcomes including hypertension, increased urinary albumin:creatinine ratio, and significantly increased serum creatinine, phosphate and urea. STNx mice developed significant left ventricular hypertrophy without reduced ejection fraction or cardiac fibrosis. Analysis of intra-renal inflammation revealed persistent recruitment of Ly6C^hi monocytes transitioning to pro-fibrotic inflammatory macrophages in STNx kidneys. Unlike 129S2/SV mice, C57BL/6 mice exhibited renal fibrosis without proteinuria, renal dysfunction, or cardiac pathology. Therefore, the 129S2/SV genetic background is susceptible to induction of progressive proteinuric renal disease and cardiac hypertrophy using our refined, single-step flank STNx method. This reproducible model could be used to study the systemic pathophysiological changes induced by CKD in the kidney and the heart, intra-renal inflammation and for testing new therapies for CKD.

Association of Chronic Kidney Disease with Preserved Ejection Fraction Heart Failure Is Independent of Baseline Cardiac Function

Background/Aims: Chronic kidney disease (CKD) is common among patients with heart failure with preserved ejection fraction (HFpEF) and is associated with worse clinical outcomes. This study aims to identify whether the association of CKD with HFpEF is independent of underlying echocardiographic abnormalities. Materials: We conducted a retrospective cohort study including patients without prevalent heart failure referred for echocardiography. Patients with serial echocardiograms, baseline left ventricular ejection fraction (LVEF) ≥50% and estimated glomerular filtration rate (eGFR) ≥90 mL/min/1.73 m2 were matched 1:1 with patients with eGFR <60 mL/min/1.73 m2 for age (±5 years), sex, history of hypertension or diabetes, use of renin-angiotensin inhibitors, and LVEF (±5%). A secondary analysis included patients with preserved LVEF and normal left ventricular mass index matched for the same parameters except use of renin-angiotensin inhibitors. Results: Patients with CKD were at increased risk for HFpEF admission: crude hazard ratio (HR) 1.79 (95% confidence interval [CI] 1.38–2.32, p < 0.001) and adjusted HR (for coronary disease, loop diuretics, left atrial diameter) 1.64 (95% CI 1.22–2.21, p = 0.001). LVEF and left ventricular diameter decreased over time in both groups but no difference was observed in rate of dropping. Results were similar in the secondary analysis (crude HR 1.99, 95% CI 1.07–3.71, p = 0.03 and HR adjusted for left atrial diameter 1.98, 95% CI 1.05–3.75, p = 0.04). Rate of change was similar for LVEF, pulmonary artery pressure, and left ventricular mass index in both groups. Conclusion: CKD is independently associated with incident HFpEF despite a similar change in relevant echocardiographic parameters in patients with or without CKD.

Urinary Biomarkers of Tubular Damage Are Associated with Mortality but Not Cardiovascular Risk among Systolic Blood Pressure Intervention Trial Participants with Chronic Kidney Disease

BACKGROUND

Kidney tubulointerstitial fibrosis on biopsy is a strong predictor of chronic kidney disease (CKD) progression, and CKD is associated with elevated risk of cardiovascular disease (CVD). Tubular health is poorly quantified by traditional kidney function measures, including estimated glomerular filtration rate (eGFR) and albuminuria. We hypothesized that urinary biomarkers of tubular injury, inflammation, and repair would be associated with higher risk of CVD and mortality in persons with CKD.

METHODS

We measured urinary concentrations of interleukin-18 (IL-18), kidney injury molecule-1, neutrophil gelatinase-associated lipocalin, monocyte chemoattractant protein-1, and chitinase-3-like protein-1 (YKL-40) at baseline among 2,377 participants of the Systolic Blood Pressure Intervention Trial who had an eGFR < 60 mL/min/1.73 m2. We used Cox proportional hazards models to evaluate biomarker associations with CVD events and all-cause mortality.

RESULTS

At baseline, the mean age of participants was 72 ± 9 years, and eGFR was 48 ± 11 mL/min/1.73 m2. Over a median follow-up of 3.8 years, 305 CVD events (3.6% per year) and 233 all-cause deaths (2.6% per year) occurred. After multivariable adjustment including eGFR, albuminuria, and urinary creatinine, none of the biomarkers showed statistically significant associations with CVD risk. Urinary IL-18 (hazard ratio [HR] per 2-fold higher value, 1.14; 95% CI 1.01-1.29) and YKL-40 (HR per 2-fold higher value, 1.08; 95% CI 1.02-1.14) concentrations were each incrementally associated with higher mortality risk. Associations were similar when stratified by randomized blood pressure arm.

CONCLUSIONS

Among hypertensive trial participants with CKD, higher urinary IL-18 and YKL-40 were associated with higher risk of mortality, but not CVD.

Relationship of mildly increased albuminuria and coronary artery revascularization outcomes in patients with diabetes

BACKGROUND

The aim of this study was to examine the relationship of albuminuria to cardiovascular disease outcomes in diabetic patients undergoing treatment for stable coronary artery disease.

METHODS AND RESULTS

We analyzed data from 2176 participants of the Bypass Angioplasty Revascularization Investigation in type-2 diabetes (BARI-2D) trial, a randomized clinical trial comparing Percutaneous coronary intervention/Coronary artery bypass grafting (PCI/CABG) to medical therapy for people with diabetes. The population was stratified by baseline spot urine albumin-creatinine ratio (uACR) into normal (uACR <10 mg/g), mildly (uACR ≥10 mg/g < 30 mg/g), moderately (uACR ≥30 mg/g < 300 mg/g) and severely increased (uACR ≥300 mg/g) groups, and outcomes compared between groups. Death, myocardial infarction (MI) and/or stroke were experienced by 489 patients at a mean follow-up of 4.3 ± 1.5 years. Compared with normal uACR, mildly increased uACR was associated with a 1.4 times (P = 0.042) increase in all-cause mortality. Additionally, nonwhites with type-II diabetes and stable coronary artery disease who had mildly increased albuminuria had a Hazard ratio (HR) of 3.3 times (P = 0.028) for cardiovascular death, 3.1 times for (P = 0.002) all-cause mortality, and two times for (P = 0.015) MI during follow-up.

CONCLUSIONS

Mildly increased albuminuria is a significant predictor of all-cause mortality in those with type-II diabetes mellitus and stable coronary artery disease, as well as for cardiovascular events those who are nonwhites.

Cardiovascular Disease Outcomes Related to Early Stage Renal Impairment After Liver Transplantation

BACKGROUND

In the general population, even mild renal disease is associated with increased cardiovascular (CV) complications. Whether this is true in liver transplant recipients (LTR) is unknown.

METHODS

This was a retrospective cohort study of 671 LTR (2002-2012) from a large urban tertiary care center and 37 322 LTR using Vizient hospitalization data linked to the United Network for Organ Sharing. The 4-variable Modification of Diet in Renal Disease equation estimated glomerular filtration rate (eGFR). Outcomes were 1-year CV complications (death/hospitalization from myocardial infarction, heart failure, atrial fibrillation, cardiac arrest, pulmonary embolism, or stroke) and mortality. Latent mixture modeling identified trajectories in eGFR in the first liver transplantation (LT) year in the 671 patients.

RESULTS

Mean (SD) eGFR was 72.1 (45.7) mL/min per 1.73 m. Six distinct eGFR trajectories were identified in the local cohort (n = 671): qualitatively normal-slow decrease (4% of cohort), normal-rapid decrease (4%), mild-stable (18%), mild-slow decrease (35%), moderate-stable (30%), and severe-stable (9%). In multivariable analyses adjusted for confounders and baseline eGFR, the greatest odds of 1-year CV complications were in the normal-rapid decrease group (odds ratio, 10.6; 95% confidence interval, 3.0-36.9). Among the national cohort, each 5-unit lower eGFR at LT was associated with a 2% and 5% higher hazard of all-cause and CV-mortality, respectively (P < 0.0001), independent of multiple confounders.

CONCLUSIONS

Even mild renal disease at the time of LT is a risk factor for posttransplant all-cause and CV mortality. More rapid declines in eGFR soon after LT correlate with risk of adverse CV outcomes, highlighting the need to study whether early renal preservation interventions also reduce CV complications.

Cystatin C measurement leads to lower metformin dosage in elderly type 2 diabetic patients

The aim of this study was to provide evidence for the hypothesis that estimated glomerular filtration rate from serum Cystatin C (eGFRcys) is better to be determined for all elderly type 2 diabetes mellitus (T2DM) patients based on eGFRcys upward and downward reclassification rate for hypothetical metformin dose reduction by eGFRcys at the GFR decision point of 45 mL/min/1.73 m². A total of 265 consecutive T2DM elderly patients (age range 65‐91 years) from outpatient diabetic clinic were included in the study. The Kidney Disease Improving Global Outcomes (KDIGO) guidelines for metformin dosing were strictly followed. Estimated glomerular filtration rate from serum creatinine (eGFRcrea) led to results of metformin eligibility. Each of the results of eGFRcrea‐based eligibility was further compared to eGFRcys‐based eligibility. Creatinine was measured by enzymatic method standardized against international reference material SRM 967. Cystatin C was determined by method traceable to DA ERM 471 international standard. eGFRcrea and eGFRcys were calculated according to Chronic Kidney Disease Epidemiology Collaboration (CKD‐EPI) equations. A downward reclassification rate was higher than upward reclassification rate (31 vs 3, respectively; P < 0.0001). The median (IQR) eGFRcrea was higher than eGFRcys (73 (58‐85) vs 63 (50‐75) mL/min/1.73 m², respectively; P < 0.0001). eGFRcys reclassified significant proportion of patients with T2DM from metformin eligible CKD stages to less or non‐eligible stages. The downward reclassification was more frequent in patients older than 80 years (P < 0.01). Cystatin C‐based eGFR selects more complicated patients, where lower doses of metformin are possibly advisable. We recommend calculating both eGFRcrea and eGFRcys for metformin dosing in elderly patients with T2DM.

Urinary Biomarkers of Kidney Tubular Damage and Risk of Cardiovascular Disease and Mortality in Elders

RATIONALE & OBJECTIVE

Novel urinary biomarkers have enabled earlier detection of kidney tubular damage, but their prognostic value for adverse cardiovascular outcomes is uncertain. We hypothesized that tubular damage, measured by urine α₁-microglobulin (A1M), amino-terminal propeptide of type III procollagen (PIIINP), and neutrophil gelatinase-associated lipocalin (NGAL), would be associated with higher risks for cardiovascular events and mortality among elders.

STUDY DESIGN

Case-cohort study.

SETTING & PARTICIPANTS

This study included a randomly selected subcohort (n=502), cardiovascular disease (CVD) cases (n=245), and heart failure cases (n=220) from the Health, Aging, and Body Composition (Health ABC) Study.

PREDICTORS

Baseline urine A1M, PIIINP, and NGAL concentrations.

OUTCOMES

Incident CVD, heart failure, and all-cause mortality.

ANALYTICAL APPROACH

Cox proportional hazards models were used to evaluate biomarker associations with each outcome.

RESULTS

At baseline, mean age was 74 years and estimated glomerular filtration rate was 73mL/min/1.73m². After adjustment for demographics, estimated glomerular filtration rate, albumin-creatinine ratio, and other cardiovascular risk factors, each doubling in biomarker concentration was associated with the following adjusted HRs for CVD: A1M, 1.51 (95% CI, 1.16-1.96); PIIINP, 1.21 (95% CI, 1.00-1.46); and NGAL, 1.12 (95% CI, 1.05-1.20). There were 248 deaths in the subcohort during a median follow-up of 12.4 years. Adjusted associations of each biomarker (HR per doubling) with all-cause mortality were: A1M, 1.29 (95% CI, 1.10-1.51); PIIINP, 1.05 (95%, 0.94-1.18); and NGAL, 1.07 (95% CI, 1.02-1.12). Biomarker concentrations did not have statistically significant associations with heart failure after multivariable adjustment.

LIMITATIONS

Urine biomarkers were measured at a single time point; no validation cohort available.

CONCLUSIONS

Kidney tubular damage is an independent risk factor for CVD and death among elders. Future studies should investigate mechanisms by which kidney tubular damage may adversely affect cardiovascular risk.

Cardiovascular Outcomes According to Urinary Albumin and Kidney Disease in Patients With Type 2 Diabetes at High Cardiovascular Risk: Observations From the SAVOR-TIMI 53 Trial

Importance

An elevated level of urinary albumin to creatinine ratio (UACR) is a marker of renal dysfunction and predictor of kidney failure/death in patients with type 2 diabetes. The prognostic use of UACR in established cardiac biomarkers is not well described.

Objective

To evaluate whether UACR offers incremental prognostic benefit beyond risk factors and established plasma cardiovascular biomarkers.

Design, Setting, and Participants

The Saxagliptin Assessment of Vascular Outcomes Recorded in Patients With Diabetes Mellitus-Thrombolysis in Myocardial Infarction (SAVOR-TIMI) 53 study was performed from May 2010 to May 2013 and evaluated the safety of saxagliptin vs placebo in patients with type 2 diabetes with overt cardiovascular disease or multiple risk factors. Median follow-up was 2.1 years (interquartile range, 1.8-2.3 years).

Interventions

Patients were randomized to saxagliptin vs placebo plus standard care.

Main Outcomes and Measures

Baseline UACR was measured in 15 760 patients (95.6% of the trial population) and categorized into thresholds.

Results

Of 15 760 patients, 5205 were female (33.0%). The distribution of UARC categories were: 5805 patients (36.8%) less than 10 mg/g, 3891 patients (24.7%) at 10 to 30 mg/g, 4426 patients (28.1%) at 30 to 300 mg/g, and 1638 patients (10.4%) at more than 300 mg/g. When evaluated without cardiac biomarkers, there was a stepwise increase with each higher UACR category in the incidence of the primary composite end point (cardiovascular death, myocardial infarction, or ischemic stroke) (3.9%, 6.9%, 9.2%, and 14.3%); cardiovascular death (1.4%, 2.6%, 4.1%, and 6.9%); and hospitalization for heart failure (1.5%, 2.5%, 4.0%, and 8.3%) (adjusted P < .001 for trend). The net reclassification improvement at the event rate for each end point was 0.081 (95% CI, 0.025 to 0.161), 0.129 (95% CI, 0.029 to 0.202), and 0.056 (95% CI, -0.005 to 0.141), respectively. The stepwise increased cardiovascular risk associated with a UACR of more than 10 mg/g was also present within each chronic kidney disease category. The UACR was associated with outcomes after including cardiac biomarkers. However, the improvement in discrimination and reclassification was attenuated; net reclassification improvement at the event rate was 0.022 (95% CI, -0.022 to 0.067), -0.008 (-0.034 to 0.053), and 0.043 (-0.030 to 0.052) for the primary end point, cardiovascular death, and hospitalization for heart failure, respectively.

Conclusions and Relevance

In patients with type 2 diabetes, UACR was independently associated with increased risk for a spectrum of adverse cardiovascular outcomes. However, the incremental cardiovascular prognostic value of UACR was minimal when evaluated together with contemporary cardiac biomarkers.

Trial Registration

clinicaltrials.gov Identifier: NCT01107886.

Risk Factors for Heart Failure in Patients With Chronic Kidney Disease: The CRIC (Chronic Renal Insufficiency Cohort) Study

Background

Heart failure is common in patients with chronic kidney disease. We studied risk factors for incident heart failure among 3557 participants in the CRIC (Chronic Renal Insufficiency Cohort) Study.

Methods and Results

Kidney function was assessed by estimated glomerular filtration rate (eGFR) using serum creatinine, cystatin C, or both, and 24‐hour urine albumin excretion. During an average of 6.3 years of follow‐up, 452 participants developed incident heart failure. After adjustment for age, sex, race, and clinical site, hazard ratio (95% CI) for heart failure associated with 1 SD lower creatinine‐based eGFR was 1.67 (1.49, 1.89), 1 SD lower cystatin C‐based‐eGFR was 2.43 (2.10, 2.80), and 1 SD higher log‐albuminuria was 1.65 (1.53, 1.78), all P<0.001. When all 3 kidney function measures were simultaneously included in the model, lower cystatin C‐based eGFR and higher log‐albuminuria remained significantly and directly associated with incidence of heart failure. After adjusting for eGFR, albuminuria, and other traditional cardiovascular risk factors, anemia (1.37, 95% CI 1.09, 1.72, P=0.006), insulin resistance (1.16, 95% CI 1.04, 1.28, P=0.006), hemoglobin A1c (1.27, 95% CI 1.14, 1.41, P<0.001), interleukin‐6 (1.15, 95% CI 1.05, 1.25, P=0.002), and tumor necrosis factor‐α (1.10, 95% CI 1.00, 1.21, P=0.05) were all significantly and directly associated with incidence of heart failure.

Conclusions

Our study indicates that cystatin C‐based eGFR and albuminuria are better predictors for risk of heart failure compared to creatinine‐based eGFR. Furthermore, anemia, insulin resistance, inflammation, and poor glycemic control are independent risk factors for the development of heart failure among patients with chronic kidney disease.

Cardiovascular risk prediction in people with chronic kidney disease

PURPOSE OF REVIEW

Clinical guidelines are not consistent regarding whether or how to utilize information on measures of chronic kidney disease (CKD) for predicting the risk of cardiovascular disease (CVD). This review summarizes recent literature regarding CVD prediction in the context of CKD.

RECENT FINDINGS

Previous studies used different definitions of CKD measures and CVD outcomes, and applied distinct statistical approaches. A recent individual-level meta-analysis from the CKD Prognosis Consortium is of value as it has uniformly investigated creatinine-based estimated glomerular filtration rate (eGFR) and albuminuria as CKD measures and applied the same statistical approach across 24 cohorts with more than 630 000 participants. In this meta-analysis, eGFR and albuminuria improve CVD risk prediction beyond traditional CVD risk factors, particularly for CVD mortality and heart failure. Albuminuria demonstrates more evident improvement than eGFR. Moreover, several recent studies have shown that other filtration markers, for example, cystatin C and β2-microglobulin, and measures of atherosclerosis or cardiac damage (e.g., coronary artery calcium and cardiac troponins) can further improve CVD prediction in the CKD population.

SUMMARY

Future clinical guidelines may require updates regarding whether/how to incorporate CKD measures and other biomarkers in CVD prediction, depending on the CVD outcomes of interest, target population, and availability of those measures/biomarkers in that population.

Mendelian Randomisation study of the influence of eGFR on coronary heart disease

Impaired kidney function, as measured by reduced estimated glomerular filtration rate (eGFR), has been associated with increased risk of coronary heart disease (CHD) in observational studies, but it is unclear whether this association is causal or the result of confounding or reverse causation. In this study we applied Mendelian randomisation analysis using 17 genetic variants previously associated with eGFR to investigate the causal role of kidney function on CHD. We used 13,145 participants from the UCL-LSHTM-Edinburgh-Bristol (UCLEB) Consortium and 194,427 participants from the Coronary ARtery DIsease Genome-wide Replication and Meta-analysis plus Coronary Artery Disease (CARDIoGRAMplusC4D) consortium. We observed significant association of an unweighted gene score with CHD risk (odds ratio = 0.983 per additional eGFR-increasing allele, 95% CI = 0.970–0.996, p = 0.008). However, using weights calculated from UCLEB, the gene score was not associated with disease risk (p = 0.11). These conflicting results could be explained by a single SNP, rs653178, which was not associated with eGFR in the UCLEB sample, but has known pleiotropic effects that prevent us from drawing a causal conclusion. The observational association between low eGFR and increased CHD risk was not explained by potential confounders, and there was no evidence of reverse causation, therefore leaving the remaining unexplained association as an open question.

Comparison of cystatin C- and creatinine-based estimated glomerular filtration rates for predicting all-cause mortality in Japanese patients with type 2 diabetes: the Fukuoka Diabetes Registry

BACKGROUND

There is little information about the predictive ability of cystatin C-based estimated glomerular filtration rates (eGFR_Cys) for all-cause mortality in Asian populations. We compared the discriminatory ability of eGFR_Cys for all-cause mortality with that of creatinine-based estimated glomerular filtration rates (eGFR_Cr) in Japanese patients with type 2 diabetes.

METHODS

A total of 4869 participants were classified into four categories (eGFR ≤29, 30-59, 60-89, and ≥90 ml/min/1.73 m²) by eGFR_Cr and eGFR_Cys, and followed up for a median of 3.3 years.

RESULTS

150 deaths were identified. The multivariable-adjusted risk of all-cause mortality was significantly increased in eGFR_Cr ≤29 ml/min/1.73 m² compared with eGFR_Cr ≥90 ml/min/1.73 m² [hazard ratio (HR) 2.4 (95 % confidence interval (95 % CI) 1.2-5.0)], whereas it was significantly increased in eGFR_Cys 59 ml/min/1.73 m² or lower [30-59 ml/min/1.73 m², HR 1.9 (95 % CI 1.1-3.5); ≤29 ml/min/1.73 m², HR 5.8 (95 % CI 2.8-12.0)]. Comparing eGFR_Cys with eGFR_Cr, the proportions of participants reclassified to lower and higher eGFR stages were 6.3 and 28.8 %, respectively. The multivariable-adjusted HRs for all-cause mortality were 1.8 (95 % CI 1.1-2.9) and 0.7 (95 % CI 0.4-1.1), respectively. The C statistic of the model including eGFR_Cys and other risk factors was significantly increased compared with the model including eGFR_Cr. The net reclassification improvement and the integrated discrimination improvement were significantly positive.

CONCLUSIONS

Our findings suggest that eGFR_Cys has a stronger association with all-cause mortality and is superior to eGFR_Cr for predicting all-cause mortality in Japanese patients with type 2 diabetes.

Cystatin C estimated glomerular filtration rate and all-cause and cardiovascular disease mortality risk in the general population: AusDiab study

AIMS

Uncertainties about the role of cystatin C-based estimated glomerular filtration rate (eGFR) in the prediction of cardiovascular disease (CVD) beyond traditional CVD risk factors remain. We assessed contributions of eGFR to CVD and mortality in the general population.

METHODS

Using 14 year follow-up data on 9353 adults without a reported history of CVD from the Australian Diabetes, Obesity and Lifestyle study, we assessed the contributions of eGFR (assessed by cystatin C (eGFR_cysC ) and serum creatinine (eGFR_cr ) and albuminuria (uACR) to total and CVD mortality.

RESULTS

After adjusting for age, sex, CVD risk factors and uACR, compared with an eGFR_cysC >90 mL/min per 1.73 m² , eGFR_cysC <60 mL/min per 1.73 m² was associated with 56% and 73% increases in the risks for all-cause and CVD mortality, respectively. The respective changes for the c-statistic when eGFR_cysC was added to a risk prediction model were 0.003 (95% confidence interval: 0.001 to 0.005) and 0.002 (95% confidence interval: -0.001 to 0.006). The net proportion of non-events assigned a lower-risk category significantly improved with the addition of eGFR (non-event net reclassification index eGFR_cr : 1.0% and eGFR_cysC : 1.5%) for all-cause mortality, but for CVD mortality, improvements were only significant when eGFR was combined with uACR. The net proportion of events assigned a higher-risk category was not significantly improved.

CONCLUSION

In our community-based cohort, reduced eGFR_cysC was associated with all-cause and CVD mortality. The addition of chronic kidney disease measures to risk prediction models improved overall risk stratification among those at low risk as opposed to those at high baseline risk of mortality.

Arterial Stiffness and Decline in Kidney Function

BACKGROUND AND OBJECTIVES

The independent link between arterial stiffness and CKD remains unknown. We investigated the association of indicators of arterial stiffness with decline in kidney function.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

We studied 3666 participants (mean age =65 years old; 58% women) from the Rotterdam Study. Pulse pressure (PP), carotid stiffness, and pulse wave velocity (PWV) were measured. We created genetic risk scores for PP and PWV. Annual declines in kidney function and incident CKD were assessed using eGFR. To put our findings in context of the literature, we performed a meta-analysis of the available population-based studies.

RESULTS

After a median (interquartile range) follow-up time of 11 (10.7-11.3) years, 601 participants with incident CKD were recognized. In the model adjusted for age, sex, mean arterial pressure, heart rate, and baseline GFR, each SD higher PP was associated with 0.15-ml/min per 1.73 m(2) steeper annual eGFR decline (95% confidence interval [95% CI], 0.10 to 0.20) and 11% higher risk of incident CKD (95% CI, 1.05 to 1.18). Each SD greater carotid stiffness was associated with 0.08-ml/min per 1.73 m(2) steeper annual eGFR decline (95% CI, 0.04 to 0.13) and 13% higher risk of incident CKD (95% CI, 1.05 to 1.22). Each SD higher PWV was associated with 7% higher risk of incident CKD (95% CI, 1.00 to 1.14). Incorporating our findings in a meta-analysis, each SD higher PP and PWV were associated with 16% (95% CI, 1.12 to 1.21) and 8% (95% CI, 1.03 to 1.14) higher risks of incident CKD. Each SD higher PP genetic risk score was associated with 0.06-ml/min per 1.73 m(2) steeper annual eGFR decline (95% CI, 0.01 to 0.10) and 8% higher risk of incident CKD (95% CI, 1.03 to 1.14). There was no association between PWV genetic risk score and kidney function decline.

CONCLUSIONS

Higher indices of arterial stiffness are associated with steeper decline in kidney function. This suggests that vascular stiffness could be considered as a target for delaying decline in kidney function.

Plasma kidney injury molecule-1 in heart failure: renal mechanisms and clinical outcome

AIMS

Urinary kidney injury molecule-1 (KIM-1) is a marker of tubular damage and associated with worse outcome in heart failure (HF). Plasma KIM-1 has not been described in HF.

METHODS AND RESULTS

In a renal mechanistic cohort of 120 chronic HF patients, we established the association between plasma KIM-1, renal invasive haemodynamic parameters {renal blood flow ([(131) I]hippuran clearance) and measured glomerular filtration rate (GFR; [(125) I]iothalamate)} and urinary tubular damage markers. The association between plasma KIM-1, plasma creatinine, and clinical outcome was further explored in a cohort of 2033 acute HF patients. Median plasma KIM-1 was 171.5 pg/mL (122.8-325.7) in chronic (n = 99) and 295.1 pg/mL (182.2-484.2) in acute HF (n = 1588). In chronic HF, plasma KIM-1 was associated with GFR (P < 0.001), creatinine, and cystatin C. Plasma KIM-1 was associated with urinary N-acetyl-β-d-glucosaminidase (NAG), but not with other urinary tubular damage markers. Log plasma KIM-1 predicted adverse clinical outcome after adjustment for age, gender, and GFR [hazard ratio (HR) 1.94, 95% confidence interval (CI) 1.07-3.53, P = 0.030]. Statistical significance was lost after correction for NT-proBNP (HR 1.61, 95% CI 0.81-3.20, P = 0.175). In acute HF, higher plasma KIM-1 levels were associated with higher creatinine, lower albumin, and presence of diabetes. Log plasma KIM-1 predicted 60-day HF rehospitalization (HR 1.27, 95% CI 1.03-1.55, P = 0.024), but not 180-day mortality or 60-day death or renal or cardiovascular rehospitalization.

CONCLUSIONS

Plasma KIM-1 is associated with glomerular filtration and urinary NAG, but not with other urinary tubular damage markers. Plasma KIM-1 does not predict outcome in chronic HF after correction for NT-proBNP. In acute HF, plasma KIM-1 predicts HF rehospitalization in multivariable analysis.

Performance of cystatin C- and creatinine-based estimated glomerular filtration rate equations depends on patient characteristics

BACKGROUND

The Kidney Disease Improving Global Outcomes (KDIGO) guideline recommends use of a cystatin C-based estimated glomerular filtration rate (eGFR) to confirm creatinine-based eGFR between 45 and 59 mL · min(-1) · (1.73 m(2))(-1). Prior studies have demonstrated that comorbidities such as solid-organ transplant strongly influence the relationship between measured GFR, creatinine, and cystatin C. Our objective was to evaluate the performance of cystatin C-based eGFR equations compared with creatinine-based eGFR and measured GFR across different clinical presentations.

METHODS

We compared the performance of the CKD-EPI 2009 creatinine-based estimated GFR equation (eGFRCr) and the newer CKD-EPI 2012 cystatin C-based equations (eGFRCys and eGFRCr-Cys) with measured GFR (iothalamate renal clearance) across defined patient populations. Patients (n = 1652) were categorized as transplant recipients (n = 568 kidney; n = 319 other organ), known chronic kidney disease (CKD) patients (n = 618), or potential kidney donors (n = 147).

RESULTS

eGFRCr-Cys showed the most consistent performance across different clinical populations. Among potential kidney donors without CKD [stage 2 or higher; eGFR >60 mL · min(-1) · (1.73 m(2))(-1)], eGFRCys and eGFRCr-Cys demonstrated significantly less bias than eGFRCr; however, all 3 equations substantially underestimated GFR when eGFR was <60 mL · min(-1) · (1.73 m(2))(-1). Among transplant recipients with CKD stage 3B or greater [eGFR <45 mL · min(-1) · (1.73 m(2))(-1)], eGFRCys was significantly more biased than eGFRCr. No clear differences in eGFR bias between equations were observed among known CKD patients regardless of eGFR range or in any patient group with a GFR between 45 and 59 mL · min(-1) · (1.73 m(2))(-1).

CONCLUSIONS

The performance of eGFR equations depends on patient characteristics that are readily apparent on presentation. Among the 3 CKD-EPI equations, eGFRCr-Cys performed most consistently across the studied patient populations.

Coronary heart disease risk factors and outcomes in the twenty-first century: findings from the REasons for Geographic and Racial Differences in Stroke (REGARDS) Study

REasons for Geographic and Racial Differences in Stroke (REGARDS) is a longitudinal study supported by the National Institutes of Health to determine the disparities in stroke-related mortality across USA. REGARDS has published a body of work designed to understand the disparities in prevalence, awareness, treatment, and control of coronary heart disease (CHD) and its risk factors in a biracial national cohort. REGARDS has focused on racial and geographical disparities in the quality and access to health care, the influence of lack of medical insurance, and has attempted to contrast current guidelines in lipid lowering for secondary prevention in a nationwide cohort. It has described CHD risk from nontraditional risk factors such as chronic kidney disease, atrial fibrillation, and inflammation (i.e., high-sensitivity C-reactive protein) and has also assessed the role of depression, psychosocial, environmental, and lifestyle factors in CHD risk with emphasis on risk factor modification and ideal lifestyle factors. REGARDS has examined the utility of various methodologies, e.g., the process of medical record adjudication, proxy-based cause of death, and use of claim-based algorithms to determine CHD risk. Some valuable insight into less well-studied concepts such as the reliability of current troponin assays to identify "microsize infarcts," caregiving stress, and CHD, heart failure, and cognitive decline have also emerged. In this review, we discuss some of the most important findings from REGARDS in the context of the existing literature in an effort to identify gaps and directions for further research.

Cystatin C-based estimated glomerular filtration rate and periodontitis

BACKGROUND AND OBJECTIVE

Accumulating evidence suggests that decreased kidney function characterised by low estimated glomerular filtration rate (eGFR) may be associated with periodontitis. Recent studies have suggested that the use of cystatin C strengthens the association between the eGFR and the risks of adverse outcomes in decreased kidney function. The aim of this cross-sectional study was to investigate the association of cystatin C-based eGFR (eGFRcys) and creatinine-based eGFR (eGFRcreat), the commonly used method to assess kidney function, with periodontitis in 502 Japanese women (average age, 68.6 years).

MATERIALS AND METHODS

GFR was estimated from serum cystatin C and serum creatinine, respectively, using the Japanese equation for GFR. Participants were classified into five groups according to their eGFRcys and eGFRcreat values. Poisson regression models with robust error variance assessed the associations of eGFRcys and eGFRcreat with periodontitis. Tests for trends were performed by fitting the five-category eGFR variables in their continuous form to the regression models.

RESULTS

Participants with eGFRcys < 50 ml/min/1.73 m(2) were at significantly higher risk of periodontitis compared with the reference group (≥90 ml/min/1.73 m(2) ) (adjusted relative risk = 2.12, 95% confidence interval = 1.12 to 4.02). Additionally, there was a trend towards a higher risk of periodontitis among participants with lower eGFRcys values (p for trend in the multivariable model = 0.008). In contrast, eGFRcreat did not show a significant association with periodontitis.

CONCLUSION

The findings of this study of Japanese older women showed that eGFRcys had a stronger and more linear association with periodontitis than eGFRcreat.

Association of serum levels of FGF23 and α-Klotho with glomerular filtration rate and proteinuria among cardiac patients

Background

Expression and/or excretion of fibroblast growth factor-23 (FGF23) and its co-receptor Klotho are altered in patients with end-stage renal disease. The possibility that the FGF23/α-Klotho system mediates the aggravated cardiovascular outcome among patients with chronic kidney disease (CKD) has been suggested. We determined whether FGF23 and α-Klotho concentrations are altered among patients with reduced renal function and proteinuria.

Methods

Serum FGF23 and α-Klotho were measured in cardiology patients who were not undergoing chronic hemodialysis. Estimated glomerular filtration rate (eGFR) was correlated negatively with FGF23 and positively with α-Klotho.

Results

The correlation between FGF23 and the renal tubular maximum reabsorption rate of phosphate to the GFR (TmP/GFR) was not significant, but that between FGF23 and serum calcium or inorganic phosphate was significant among patients with an estimated GFR of less than 60 mL/min/m². By stepwise multivariate regression analysis, eGFR was selected as significant predictor for FGF23 or α-Klotho among patients with an estimated GFR of less than 60 mL/min/m²; however, urine albumin/creatinine ratio was not selected as a predictor for FGF23 or α-Klotho irrespective of the eGFR levels. In patients with eGFR of <60 mL/min/1.73 m², UACR was significantly associated with log(FGF23); but, this association did not remain statistically significant in a multivariate model.

Conclusions

Among cardiology patients with various stages of CKD, serum concentrations of FGF23 and α-Klotho were associated with renal function, but not with the extent of proteinuria.