Prognostic Value of Hemoglobin Concentration on Renal Outcomes with Diabetic Kidney Disease: A Retrospective Cohort Study

Objective

Diabetic kidney disease (DKD) patients with anemia face an elevated risk of glomerular filtration rate decline. However, the association between hemoglobin and estimated Glomerular Filtration Rate (eGFR) progression remains to be elucidated.

Methods

A retrospective cohort of 815 subjects with DKD was followed from January 2010 to January 2023. A Cox proportional hazard regression model was utilized to explore the predictive role of hemoglobin in renal outcomes. Renal outcomes were defined as a composite endpoint, including a 50% decline in eGFR from baseline or progression to End-Stage Renal Disease (ESRD). To unveil any nonlinear relationship between hemoglobin and renal outcomes, Cox proportional hazard regression with cubic spline functions and smooth curve fitting was conducted. Additionally, subgroup analyses were performed to identify specific patient populations that might derive greater benefits from higher hemoglobin.

Results

Among the 815 DKD subjects, the mean age was 56.482 ± 9.924 years old, and 533 (65.4%) were male. The mean hemoglobin was 121.521±22.960 g/L. The median follow-up time was 21.103±18.335 months. A total of 182 (22.33%) individuals reached the renal composite endpoint during the study period. After adjusting for covariates, hemoglobin was found to exert a negative impact on the renal composite endpoint in patients with DKD (HR 0.975, 95% CI [0.966, 0.984]). A nonlinear relationship between hemoglobin and the renal composite endpoint was identified with an inflection point at 109 g/L. Subgroup analysis unveiled a more pronounced association between hemoglobin and renal prognosis in males.

Conclusion

Hemoglobin emerges as a predictive indicator for the renal prognosis of diabetic kidney disease in China. This study reveals a negative and non-linear relationship between hemoglobin levels and the renal composite endpoint. A substantial association is noted when hemoglobin surpasses 109 g/L in relation to the renal composite endpoint.

Metabolic Profiles of Type 2 Diabetes and Their Association With Renal Complications

CONTEXT

The components of metabolic syndrome (MetS) are interrelated and associated with renal complications in patients with type 2 diabetes (T2D).

OBJECTIVE

We aimed to reveal prevalent metabolic profiles in patients with T2D and identify which metabolic profiles were risk markers for renal progression.

METHODS

A total of 3556 participants with T2D from a hospital (derivation cohort) and 931 participants with T2D from a community survey (external validation cohort) were included. The primary outcome was the onset of diabetic kidney disease (DKD), and secondary outcomes included estimated glomerular filtration rate (eGFR) decline, macroalbuminuria, and end-stage renal disease (ESRD). In the derivation cohort, clusters were identified using the 5 components of MetS, and their relationships with the outcomes were assessed. To validate the findings, participants in the validation cohort were assigned to clusters. Multivariate odds ratios (ORs) of the primary outcome were evaluated in both cohorts, adjusted for multiple covariates at baseline.

RESULTS

In the derivation cohort, 6 clusters were identified as metabolic profiles. Compared with cluster 1, cluster 3 (severe hyperglycemia) had increased risks of DKD (hazard ratio [HR] [95% CI]: 1.72 [1.39-2.12]), macroalbuminuria (2.74 [1.84-4.08]), ESRD (4.31 [1.16-15.99]), and eGFR decline [P < .001]; cluster 4 (moderate dyslipidemia) had increased risks of DKD (1.97 [1.53-2.54]) and macroalbuminuria (2.62 [1.61-4.25]). In the validation cohort, clusters 3 and 4 were replicated to have significantly increased risks of DKD (adjusted ORs: 1.24 [1.07-1.44] and 1.39 [1.03-1.87]).

CONCLUSION

We identified 6 prevalent metabolic profiles in patients with T2D. Severe hyperglycemia and moderate dyslipidemia were validated as significant risk markers for DKD.

Rapid decline of kidney function increases fracture risk in the general population: Insights from TLGS

BACKGROUND

Although the association between Chronic Kidney Disease (CKD) and all-cause fractures was addressed in previous studies, the association between estimated glomerular filtration rate (eGFR) decline and fractures was poorly addressed. For the first time we examined the association between rapid kidney function decline (RKFD) and fracture incidence among Iranian general population.

METHODS

In a Tehranian community-based cohort, RKFD was defined as a 30 % decline in eGFR over 2-3 years. Cox proportional hazards models, adjusted for age, sex, current eGFR, diabetes mellitus, hypertension, dyslipidemia, current smoking, obesity status, waist circumference, prevalent cardiovascular diseases, aspirin, steroid use, education level, and marital status, were used to examine the association of RKFD with different fracture outcomes.

RESULTS

Among 5305 (3031 women) individuals aged ≥30 years, during the median follow-up of 9.62 years, 226 fracture events were observed. The multivariable hazard ratio of RKFD for any-fracture events, lower-extremity, and major osteoporotic fractures were 2.18 (95 % CI, 1.24-3.85), 2.32 (1.15-4.71), and 2.91 (1.29-6.58), respectively. These associations remained significant after accounting for the competing risk of death. The impact of RKFD on the development of incident all-cause fractures was not modified by gender [men: 2.64 (1.11-6.25) vs. women: 2.11 (1.00-4.47)] and according to current CKD status [without CKD: 2.34 (1.00-5.52) vs. with CKD: 2.59 (1.04-6.44)] (all P for interaction >0.5).

CONCLUSIONS

RKFD can increase the incidence of fractures among general population, the issue that was equally important among non-CKD individuals, emphasizing the need for early identification and management in those with rapidly declining eGFR.

A Comparison of the Decline in Glomerular Filtration Rate between Elderly Patients with Diabetes and those without Diabetes in Southwest China

OBJECTIVE

To investigate the effect of high blood glucose on the decline in the estimated glomerular filtration rate (eGFR) in the elderly.

METHODS

We compared the decline in eGFR of diabetic and non-diabetic groups in the noninterventional state and analyzed the effect of hyperglycemia on the decline in eGFR among the elderly in a retrospective analysis of 1,223 cases of elderly people aged 65 years or older with a 4-year follow-up period.

RESULTS

The prevalence of diabetes in the elderly increased significantly from 12.67% in 2017 to 16.68% in 2021. The rate of decline in eGFR in patients with diabetes was higher than in the population without diabetes, at 9.29% and 5.32%, respectively (both p <0.05).

CONCLUSION

The results of this study revealed that the prevalence of diabetes in the elderly increased significantly, and there is a more rapid decrease in the eGFR levels in those with diabetes than those without diabetes.

Predictors of decline in kidney function in the general population: a decade of follow-up from the Tehran Lipid and Glucose Study

BACKGROUND AND AIMS

We aimed to assess the potential socio-demographic, clinical, and lifestyle-related risk factors for kidney function decline (KFD), defined as ≥30% estimated glomerular filtration rate (eGFR) decline, in an Iranian cohort study.

METHODS

7190 participants (4049 women) aged 20-90 years with 2-5 eGFR data from examinations (2001-2005 to 2015-2018) were included. Cox proportional hazard models were used to examine the association between potential risk factors and eGFR decline.

RESULTS

During 11.5 years of follow-up, 1471 (889 women) participants had incident KFD with a crude incidence rate of 192.1 (182.6-202.2) per 10,000 person-year. Among the total population, older age, female gender, prehypertension, hypertension, diabetes, widowed/divorced states, higher triglycerides (TG), prevalent cardiovascular diseases (CVD), and higher baseline eGFR were significantly associated with higher, while moderate physical activity and a positive family history of diabetes were associated with lower risk of KFD (all p values <.05). Prevalent CVD in women but not men, diabetes, and hypertension among postmenopausal than premenopausal women were significant risk factors of KFD. According to the presence of chronic kidney disease (CKD) at baseline, higher eGFR decreased the risk of KFD in patients with CKD and increased KFD risk in those without CKD (all p for interactions <.05).

CONCLUSION

KFD is associated with multiple modifiable risk factors among the Iranian urban population that is affected by gender, menopausal status, and initial kidney function. Interventions targeting these factors might potentially help reduce the burden of KFD.Key messages:Menopausal status may influence the relationship between cardiometabolic risk factors and KFD;The impact of higher baseline eGFR on the risk of KFD differed between subjects with preserved kidney function and CKD patients.The interaction between gender, menopausal status, and baseline kidney function with different risk factors on KFD may help to make renal risk prediction scores to identify those in the general population at risk who may benefit from early prevention.

The Renal Composite Benefit of Sodium Glucose Co-Transporter 2 Inhibitors Should Ideally Be Assessed Based on a Standardised Definition: A Meta-Analysis of Randomised Controlled Trials

(1) Background: Chronic kidney disease (CKD) is extremely common against the backdrop of type 2 diabetes (T2D), accounting for nearly 30-40% of cases. The conventional management strategy relie predominantly on metabolic control and the renin-angiotensin-aldosterone system (RAAS) blockage. In the last decade, sodium glucose cotransporter 2 inhibitors (SGLT-2is) have emerged as the leading molecules preventing the development of, as well as retarding, the progression to CKD. Although the evidence in support of SGLT-2is is overwhelming, the definition of renal composite outcome in the trials varied considerably. The aim of the present meta-analysis was to explore the robustness of the renal composite benefits using a uniform definition. (2) Methods: A web-based search was conducted using the Cochrane Library to identify the relevant articles for meta-analysis. RStudio (1 July 2022, Build 554) software was used to conduct the meta-analysis. Hazard ratio (HR) was the effect size used to estimate the renal composite benefit, and prediction interval was used to detect heterogeneity. In view of the differing baseline characteristic of the trials as well as different molecules used, a random effects model was used. (3) Results: There were 12 trials including 78,781 patients, identified using the search strategy, and a five-point Cochrane risk-of-bias was used to assess quality of the publications. In the overall estimation (irrespective of the definition used for the renal composite) the HR was 0.68 (95% CI 0.60-0.76, prediction interval: 0.48-0.95) in favour of SGLT-2is, devoid of heterogeneity. While using a uniform definition of eGFR ≥ 40%decline, ESKD, or renal death, the HR was 0.64 (95% CI 0.53-0.78); using eGFR ≥ 50%decline, ESKD, or renal death the HR was 0.75 (95% CI 0.59-0.97); and with doubling of serum creatinine, renal replacement therapy, or renal death, the HR was 0.67 (95% CI 0.55-0.83) in favour of SGLT-2is. However, significant heterogeneity was encountered with all these three definitions. (4) Conclusion: There is a need to analyse the renal outcomes using a uniform definition in future trials. The presence of heterogeneity might disappear with the pooling of larger number of trials. However, if heterogeneity persists, we need to identify other clinical or laboratory attributes (in addition to SGLT-2is) responsible for the positive renal outcomes.

Risk Factors for Incident CKD in Black and White Americans: The REGARDS Study

RATIONALE & OBJECTIVE

Little information exists on the incidence of and risk factors for chronic kidney disease (CKD) in contemporary US cohorts and whether risk factors differ by race, sex, or region in the United States.

STUDY DESIGN

Observational cohort study.

SETTING & PARTICIPANTS

4,198 Black and 7,799 White participants aged at least 45 years, recruited from 2003 through 2007 across the continental United States, with baseline estimated glomerular filtration rate (eGFR)>60mL/min/1.73m2 and eGFR assessed again approximately 9 years later.

EXPOSURES

Age, sex, race (Black or White), region ("stroke belt" or other), education, income, systolic blood pressure, body mass index, diabetes, coronary heart disease, hyperlipidemia, smoking, and albuminuria.

OUTCOMES

(1) eGFR change and (2) incident CKD defined as eGFR<60mL/min/1.73m2 and≥40% decrease from baseline or kidney failure.

ANALYTICAL APPROACH

Linear regression and modified Poisson regression were used to determine the association of risk factors with eGFR change and incident CKD overall and stratified by race, sex, and region.

RESULTS

Mean age of participants was 63±8 (SD) years, 54% were female, and 35% were Black. After 9.4±1.0 years of follow-up, CKD developed in 9%. In an age-, sex-, and race-adjusted model, Black race (β =-0.13; P<0.001) was associated with higher risk of eGFR change, but this was attenuated in the fully adjusted model (β=0.02; P=0.5). Stroke belt residence was independently associated with eGFR change (β =-0.10; P<0.001) and incident CKD (relative risk, 1.14 [95% CI, 1.01-1.30]). Albuminuria was more strongly associated with eGFR change (β of-0.26 vs-0.17; P=0.01 for interaction) in Black compared with White participants. Results were similar for incident CKD.

LIMITATIONS

Persons of Hispanic ethnicity were excluded; unknown duration and/or severity of risk factors.

CONCLUSIONS

Established CKD risk factors accounted for higher risk of incident CKD in Black versus White individuals. Albuminuria was a stronger risk factor for eGFR decrease and incident CKD in Black compared with White individuals. Living in the US stroke belt is a novel risk factor for CKD.

The association between fasting plasma glucose variability and incident eGFR decline: evidence from two cohort studies

BACKGROUND

Glycemic variability (GV) is developing as a marker of glycemic control, which can be utilized as a promising predictor of complications. To determine whether long-term GV is associated with incident eGFR decline in two cohorts of Tehran Lipid and Glucose Study (TLGS) and Multi-Ethnic Study of Atherosclerosis (MESA) during a median follow-up of 12.2 years.

METHODS

Study participants included 4422 Iranian adults (including 528 patients with T2D) aged ≥ 20 years from TLGS and 4290 American adults (including 521 patients with T2D) aged ≥ 45 years from MESA. The Multivariate Cox proportional hazard models were used to assess the risk of incident eGFR decline for each of the fasting plasma glucose (FPG) variability measures including standard deviation (SD), coefficient of variation (CV), average real variability (ARV), and variability independent of the mean (VIM) both as continuous and categorical variables. The time of start for eGFR decline and FPG variability assessment was the same, but the event cases were excluded during the exposure period.

RESULTS

In TLGS participants without T2D, for each unit change in FPG variability measures, the hazards (HRs) and 95% confidence intervals (CI) for eGFR decline ≥ 40% of SD, CV, and VIM were 1.07(1.01-1.13), 1.06(1.01-1.11), and 1.07(1.01-1.13), respectively. Moreover, the third tertile of FPG-SD and FPG-VIM parameters was significantly associated with a 60 and 69% higher risk for eGFR decline ≥ 40%, respectively. In MESA participants with T2D, each unit change in FPG variability measures was significantly associated with a higher risk for eGFR decline ≥ 40%.Regarding eGFR decline ≥ 30% as the outcome, in the TLGS, regardless of diabetes status, no association was shown between FPG variability measures and risk of eGFR decline in any of the models; however, in the MESA the results were in line with those of GFR decline ≥ 40%.Using pooled data from the two cohorts we found that generally FPG variability were associated with higher risk of eGFR decline ≥ 40% only among non-T2D individuals.

CONCLUSIONS

Higher FPG variability was associated with an increased risk of eGFR decline in the diabetic American population; however, this unfavorable impact was found only among the non-diabetic Iranian population.

Clonal Hematopoiesis of Indeterminate Potential and Kidney Function Decline in the General Population

RATIONALE & OBJECTIVE

Clonal hematopoiesis of indeterminate potential (CHIP), defined by the age-related ontogenesis of expanded leukemogenic variants indicative of a genetically distinct clonal leukocyte population, is associated with risk of hematologic malignancy and cardiovascular disease. In experimental models, recapitulation of CHIP promotes kidney interstitial fibrosis with direct tissue infiltration of donor macrophages. We tested the hypothesis that CHIP is associated with kidney function decline in the general population.

STUDY DESIGN

Cohort study.

SETTING & PARTICIPANTS

12,004 individuals from 3 community-based cohorts in the TOPMed Consortium.

EXPOSURE

CHIP status from whole-genome sequences obtained from DNA extracted from peripheral blood.

OUTCOME

Risk of 30% decline in estimated glomerular filtration rate (eGFR) and percent eGFR decline per year during the follow-up period.

ANALYTICAL APPROACH

Cox proportional hazards models for 30% eGFR decline end point and generalized estimating equations for annualized relative change in eGFR with meta-analysis. Study-specific estimates were combined using fixed-effect meta-analysis.

RESULTS

The median baseline eGFR was 84mL/min/1.73m2. The prevalence of CHIP was 6.6%, 9.0%, and 12.2% in persons aged 50-60, 60-70, and>70 years, respectively. Over a median follow-up period of 8 years, for the 30% eGFR outcome 205 events occurred among 1,002 CHIP carriers (2.1 events per 100 person-years) and 2,041 events in persons without CHIP (1.7 events per 100 person-years). In meta-analysis, CHIP was associated with greater risk of a 30% eGFR decline (17% [95% CI, 1%-36%] higher; P=0.04). Differences were not observed between those with baseline eGFR above or below 60mL/min/1.73m2, of age above or below 60 years, or with or without diabetes.

LIMITATIONS

Small number of participants with moderate-to-advanced kidney disease and restricted set of CHIP driver variants.

CONCLUSIONS

We report an association between CHIP and eGFR decline in 3 general population cohorts without known kidney disease. Further studies are needed to investigate this novel condition and its potential impact among individuals with overt kidney disease.

Circulating thrombospondin-2 level for identifying individuals with rapidly declining kidney function trajectory in type 2 diabetes: a prospective study of the Hong Kong West Diabetes Registry

BACKGROUND

Thrombospondin-2 (TSP2) is a matricellular protein with tissue expression induced by hyperglycaemia. TSP2 has been implicated in non-diabetic renal injury in preclinical studies and high circulating levels were associated with worse kidney function in cross-sectional clinical studies. Therefore, we investigated the prospective associations of circulating TSP2 level with kidney function decline and the trajectories of estimated glomerular filtration rate (eGFR) in type 2 diabetes.

METHODS

Baseline serum TSP2 level was measured in 5471 patients with type 2 diabetes to evaluate its association with incident eGFR decline, defined as ≥ 40% sustained eGFR decline, using multivariable Cox regression analysis. Among participants with relatively preserved kidney function (Baseline eGFR ≥ 60 ml/min/1.73m2), joint latent class modelling was employed to identify three different eGFR trajectories. Their associations with baseline serum TSP2 was evaluated using multinomial logistic regression analysis. The predictive performance of serum TSP2 level was examined using time-dependent c-statistics and calibration statistics.

RESULTS

Over a median follow-up of 8.8 years, 1083 patients (19.8%) developed eGFR decline. Baseline serum TSP2 level was independently associated with incident eGFR decline (HR 1.21, 95%CI 1.07-1.37, P = 0.002). With internal validation, incorporating serum TSP2 to a model of clinical risk factors including albuminuria led to significant improvement in c-statistics from 83.9 to 84.4 (P < 0.001). Among patients with eGFR ≥ 60 ml/min/1.73m2, baseline serum TSP2 level was independently associated with a rapidly declining eGFR trajectory (HR 1.63, 95%CI 1.26-2.10, P < 0.001).

CONCLUSION

Serum TSP2 level was independently associated with incident eGFR decline, particularly a rapidly declining trajectory, in type 2 diabetes.

Venglustat, a Novel Glucosylceramide Synthase Inhibitor, in Patients at Risk of Rapidly Progressing ADPKD: Primary Results of a Double-Blind, Placebo-Controlled, Phase 2/3 Randomized Clinical Trial

RATIONALE & OBJECTIVE

Autosomal dominant polycystic kidney disease (ADPKD) is characterized by the formation of multiple kidney cysts that leads to growth in total kidney volume (TKV) and progression to kidney failure. Venglustat is a glucosylceramide synthase inhibitor that has been shown to inhibit cyst growth and reduce kidney failure in preclinical models of ADPKD.

STUDY DESIGN

STAGED-PKD was a 2-stage, multicenter, double-blind, randomized, placebo-controlled phase 2/3 study in adults with ADPKD at risk of rapidly progressive disease, who were selected based on Mayo Clinic imaging classification of ADPKD class 1C, 1D, or 1E and an estimated glomerular filtration rate (eGFR) of 30-89.9mL/min/1.73m².

SETTING & PARTICIPANTS

Enrollment included 236 and 242 patients in stages 1 and 2, respectively.

INTERVENTIONS

In trial stage 1, the patients were randomized 1:1:1 to venglustat, 8mg; venglustat, 15mg; or placebo. In stage 2, the patients were randomized 1:1 to venglustat, 15mg (highest dose identified as safe and well tolerated in stage 1), or placebo.

OUTCOMES

Primary end points were rate of change in TKV over 18 months in stage 1 and eGFR slope over 24 months in stage 2. Secondary end points were eGFR slope over 18 months (stage 1), rate of change in TKV (stage 2), and safety/tolerability, pain, and fatigue (stages 1 and 2).

RESULTS

A prespecified interim futility analysis showed that venglustat treatment had no effect on the annualized rate of change in TKV over 18 months (stage 1) and had a faster rate of decline in eGFR slope over 24 months (stage 2). Due to this lack of efficacy, the study was terminated early.

LIMITATIONS

The short follow-up period after the end of treatment and limited generalizability of the findings.

CONCLUSIONS

In patients with rapidly progressing ADPKD, treatment with venglustat at either 8mg or 15mg showed no change in the rate of change in TKV and a faster rate of eGFR decline in STAGED-PKD despite a dose-dependent decrease in plasma glucosylceramide levels.

FUNDING

This study was funded by Sanofi.

TRIAL REGISTRATION

Registered at ClinicalTrials.gov with study number NCT03523728.

Collaboration between local nephrologists and the transplant centre ensures good outcomes in post-transplant care

Background

Despite substantial improvements in short-term kidney allograft survival, median long-term survival remains at a standstill. It is unclear whether and to what extent a transplant centre's post-transplant care influences long-term outcomes.

Methods

We retrospectively analysed 501 single kidney transplant recipients (KTRs) who underwent transplantation between 2009 and 2018 and did not develop rejection or de novo donor-specific antibodies (dnDSA) within the first post-transplant year. After that, KTRs were either followed exclusively every 3 months by the transplant centre (n = 197) or every 3 months by local nephrologists (n = 304) with only yearly follow-up by the transplant centre. We analysed kidney allograft outcomes regarding estimated glomerular filtration rate (eGFR) decline, proteinuria, development of dnDSA and rejection.

Results

No differences between the two groups were observed in the baseline characteristics and the characteristics at the end of the first post-transplant year (P > .05). KTRs followed by local nephrologists were comparable to KTRs followed by the transplant centre concerning patient survival (P = .541), kidney allograft survival (P = .385), eGFR decline (P = .488), progression of proteinuria (P > .05), the development of dnDSA (P = .335) and T-cell-mediated rejection (P = .480). KTRs followed by the transplant centre were more likely to undergo indication biopsies in case of allograft dysfunction and dnDSA (P < .001). Antibody-mediated rejection was diagnosed earlier and more frequently (P = .059), recurrent glomerulonephritis was diagnosed earlier and more frequently (P = .026) and immunosuppression was modified earlier and more frequently in response to histological findings (P = .038).

Conclusions

Our findings suggest that close collaboration between local nephrologists and the transplant centre ensures good allograft outcomes independent of the caregiver. Greater biopsy activity in the transplant centre allows for earlier diagnosis of allograft dysfunction as the basis for novel treatment options.

Tubular Secretion and Estimated GFR Decline in the Jackson Heart Study

Introduction

Secretion of solutes by the proximal tubules represents an intrinsic kidney function not directly reflected by the glomerular filtration rate (GFR). The early loss of secretory clearance may reflect unrecognized kidney dysfunction, portending future disease progression.

Methods

We designed a nested case-control study within the Jackson Heart Study (JHS), a prospective study of African American adults in Mississippi, to associate baseline differences in proximal tubular secretion of 5 endogenously produced solutes with future estimated glomerular rate (eGFR) decline. We matched 127 pairs by creatinine-eGFR, age, diabetes, and sex among the patients who provided a 24-hour urine collection; cases had a ≥25% decline in eGFR compared to <10% in controls over 10 years of follow-up. We measured baseline plasma and urine concentrations of secretory solutes using liquid chromatography-mass spectrometry to determine the odds ratio of kidney disease progression.

Results

Mean age was 60 years; 76% were women; 30% had diabetes; mean baseline eGFR was 94±20 ml/min per 1.73 m². The eGFR decline over 10 years was 38±13% in cases and 0±10% in controls. After adjustment for the matching variables plus albuminuria, systolic blood pressure, body mass index, and smoking, each 50% lower kidney clearance of isovalerylglycine, kynurenic acid, and xanthosine were associated with 1.4 to 2.2 greater odds of eGFR decline. Kynurenic acid exhibited the strongest association; each 50% lower clearance of this secretory solute was associated with 2.20-fold higher odds of eGFR decline (95% confidence interval [CI] 1.32-3.67).

Conclusion

We found that in this community-based study of adults without significant kidney disease, lower proximal tubular secretory solute clearance is associated with future eGFR decline.

Rates of Reversal of Volume Overload in Hospitalized Acute Heart Failure: Association With Long-term Kidney Function

RATIONALE & OBJECTIVE

Achievement of decongestion in acute heart failure (AHF) is associated with improved survival and cardiovascular outcomes but can be associated with acute declines in estimated glomerular filtration rate (eGFR). We examined whether the rate of in-hospital decongestion is associated with longer term kidney function decline.

STUDY DESIGN

Post hoc analysis of trial data.

SETTINGS & PARTICIPANTS

Patients with ≥2 measures of kidney function (n = 3,500) from the Efficacy of Vasopressin Antagonism in Heart Failure Outcome Study With Tolvaptan (EVEREST) trial.

EXPOSURE

In-hospital rate of change in assessments of volume overload, including B-type natriuretic peptide (BNP), N-terminal pro-B-type natriuretic peptide (NT-proBNP), and clinical congestion score (0-12); and rate of change in hemoconcentration including measures of hematocrit, albumin, and total protein.

OUTCOME

Incident chronic kidney disease GFR category 4 or worse (chronic kidney disease [CKD] categories G4-G5; defined by a new eGFR of <30 mL/min/1.73 m²) and eGFR decline of >40%.

ANALYTICAL APPROACH

Multivariable cause-specific hazards models.

RESULTS

Over median 10-month follow-up period, faster decreases in volume overload and more rapid increases in hemoconcentration were associated with a decreased risk of incident CKD G4-G5 and eGFR decline of >40%. In adjusted analyses, for every 6% faster decline in BNP per week, there was a 32% lower risk of both incident CKD G4-G5 (HR, 0.68 [95% CI, 0.58-0.79]) and eGFR decline of >40% (HR, 0.68 [95% CI, 0.57-0.80]). For every 1% faster increase per week in absolute hematocrit, there was a lower risk for both incident CKD G4-G5 (HR, 0.73 [95% CI, 0.64-0.84]) and eGFR decline of >40% (HR, 0.82 [95% CI, 0.71-0.95]), with results consistent for other biomarkers.

LIMITATIONS

Possibility of residual confounding.

CONCLUSIONS

These results provide reassurance that more rapid decongestion in patients with AHF does not increase the risk of adverse kidney outcomes in patients with heart failure.

Kidney Outcomes in Long COVID

BACKGROUND

COVID-19 is associated with increased risk of post-acute sequelae involving pulmonary and extrapulmonary organ systems-referred to as long COVID. However, a detailed assessment of kidney outcomes in long COVID is not yet available.

METHODS

We built a cohort of 1,726,683 US Veterans identified from March 1, 2020 to March 15, 2021, including 89,216 patients who were 30-day survivors of COVID-19 and 1,637,467 non-infected controls. We examined risks of AKI, eGFR decline, ESKD, and major adverse kidney events (MAKE). MAKE was defined as eGFR decline ≥50%, ESKD, or all-cause mortality. We used inverse probability-weighted survival regression, adjusting for predefined demographic and health characteristics, and algorithmically selected high-dimensional covariates, including diagnoses, medications, and laboratory tests. Linear mixed models characterized intra-individual eGFR trajectory.

RESULTS

Beyond the acute illness, 30-day survivors of COVID-19 exhibited a higher risk of AKI (aHR, 1.94; 95% CI, 1.86 to 2.04), eGFR decline ≥30% (aHR, 1.25; 95% CI, 1.14 to 1.37), eGFR decline ≥40% (aHR, 1.44; 95% CI, 1.37 to 1.51), eGFR decline ≥50% (aHR, 1.62; 95% CI, 1.51 to 1.74), ESKD (aHR, 2.96; 95% CI, 2.49 to 3.51), and MAKE (aHR, 1.66; 95% CI, 1.58 to 1.74). Increase in risks of post-acute kidney outcomes was graded according to the severity of the acute infection (whether patients were non-hospitalized, hospitalized, or admitted to intensive care). Compared with non-infected controls, 30-day survivors of COVID-19 exhibited excess eGFR decline (95% CI) of -3.26 (-3.58 to -2.94), -5.20 (-6.24 to -4.16), and -7.69 (-8.27 to -7.12) ml/min per 1.73 m² per year, respectively, in non-hospitalized, hospitalized, and those admitted to intensive care during the acute phase of COVID-19 infection.

CONCLUSIONS

Patients who survived COVID-19 exhibited increased risk of kidney outcomes in the post-acute phase of the disease. Post-acute COVID-19 care should include attention to kidney disease.

Diet quality and incident chronic kidney disease in the general population: The Lifelines Cohort Study

RATIONALE & AIMS

Healthy dietary patterns have been associated with a lower risk of chronic kidney disease (CKD). We aimed to investigate the association of a fully food-based diet quality score assessed by the Lifelines Diet Score (LLDS) with either incident CKD or eGFR decline in the general population.

METHODS

For this study, data from a prospective general population-based Lifelines cohort in the Northern Netherlands was used. Diet was assessed with a 110-item food frequency questionnaire at baseline. The LLDS, based on international evidence for diet-disease relations at the food group level, was calculated to assess diet quality. For the analysis, the score was divided into tertiles. Logistic regression was performed to evaluate the association of the LLDS at baseline with either incident CKD (eGFR <60 mL/min/1.73 m²) or a ≥20% eGFR decline at the second study visit, adjusted for relevant confounders.

RESULTS

A total of 78 346 participants free of CKD at baseline were included. During a mean (SD) follow-up of 3.6 ± 0.9 years, 2071 (2.6%) participants developed CKD and 7611 (9.7%) had a ≥20% eGFR decline. Participants in the highest tertile of LLDS had a lower risk of incident CKD (fully adjusted OR 0.83, [95% CI: 0.72-0.96]) and ≥20% eGFR decline (fully adjusted OR 0.80, [95% CI: 0.75-0.86]), compared with those in the lowest tertile. Similar dose-response associations were observed in continuous LLDS.

CONCLUSIONS

Higher adherence to a high-quality diet was associated with a lower risk of incident CKD or ≥20% eGFR decline in the general population.

Glomerular filtration rate decline in T2DM following diagnosis. The Verona newly diagnosed diabetes study-12

AIMS

Nephropathy is a complication of type 2 diabetes, with increased albuminuria and reduced glomerular filtration rate (GFR) as biomarkers. Rates of progression to end-stage-renal disease are variable among patients. In this study we have examined the GFR decline in newly diagnosed T2DM.

METHODS

A cohort of 410 patients with newly diagnosed T2DM and with at least four serum creatinine during the follow-up period were recruited. A linear model was used to calculate the decline in eGFR. A multivariable logistic model was used to identify independent predictors of rapid eGFR decline.

RESULTS

Average follow-up was 12.4 years. The eGFR change was -0.80 ± 2.23 ml/min/1.73 m² per year. Patients were arbitrarily stratified into rapid decliners (≤-3.0 ml/min/1.73 m² per year), moderate decliners (-2.9/-1 ml/min/1.73 m² per year) and slow/no decliners (>-1.0 ml/min/1.73 m² per year). Subjects in the 3 categories were 11.4%, 27.3%, and 61.3%, respectively. Albuminuria was the stronger predictor of rapid eGFR decline.

CONCLUSIONS

A rapid decline in eGFR occurs in approximately 1 out of 10 newly diagnosed subjects. This rapid decline can be predicted by widely accessible clinical features, such as albuminuria. Identification of rapid decliners may help to reduce progression toward advanced stages of nephropathy.

Acute Kidney Injury among Black Patients with Sickle Cell Trait and Sickle Cell Disease

BACKGROUND AND OBJECTIVES

Sickle cell trait and sickle cell disease are associated with faster GFR decline compared with normal hemoglobin phenotypes. We sought to compare the AKI risk in sickle cell trait/disease to normal hemoglobin phenotypes and investigate the association between AKI and GFR decline in sickle cell trait/disease.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

This multicenter observational study used registry data (January 2005-June 2018) of adult Black patients with sickle cell trait/disease (exposures) and normal hemoglobin phenotype (reference) ascertained by hemoglobin electrophoresis. Outcomes of interest (incident AKI [1.5 times baseline serum creatinine or higher], incident severe AKI [doubling of baseline serum creatinine or higher], and incident sustained AKI [AKI persisting for ≥72 hours]) were adjudicated by chart review and evaluated by Cox regression. The association between AKI and GFR decline (linear mixed models) was also investigated.

RESULTS

We identified 8968 reference patients, 1279 patients with sickle cell trait, and 254 patients with sickle cell disease with a median follow-up of 7.6 years and mean baseline serum creatinine of 0.8 mg/dl. We observed 796 AKI events, 452 sustained AKI events, and 466 severe AKI events. Compared with people with a normal hemoglobin phenotype, sickle cell trait was associated with higher risk for sustained AKI (adjusted hazard ratio, 1.64; 95% confidence interval, 1.27 to 2.11), but not AKI (adjusted hazard ratio, 1.11; 95% confidence interval, 0.91 to 1.36) or severe AKI (adjusted hazard ratio, 1.26; 95% confidence interval, 0.96 to 1.64). Sickle cell disease was associated with AKI (adjusted hazard ratio, 2.85; 95% confidence interval, 2.13 to 3.81), severe AKI (adjusted hazard ratio, 2.38; 95% confidence interval, 1.65 to 3.42), and sustained AKI (adjusted hazard ratio, 2.50; 95% confidence interval, 1.68 to 3.71). Post-AKI GFR decline was significantly faster in sickle cell trait (0.37 ml/min per 1.73 m² per year faster, P<0.01) and disease (1.69 ml/min per 1.73 m² per year faster, P<0.01) compared with the reference.

CONCLUSIONS

Sickle cell trait and disease are associated with higher risk of AKI, which is associated with accelerated decline in eGFR.

Arteriovenous access placement and renal function decline

BACKGROUND

There is controversial evidence on whether arteriovenous access (AVA) placement may protect renal function and hence should be considered in the timing of access placement. This study aimed to investigate the association between AVA placement and estimated glomerular filtration rate (eGFR) decline as compared with the placement of a peritoneal dialysis catheter (PDC) at a similar time point.

METHODS

We studied a cohort of 744 pre-dialysis patients in Stockholm, Sweden, who underwent surgery for AVA or PDC between 2006 and 2012. Data on comorbidity, medication and laboratory measures were collected 100 days before and after surgery. Patients were followed until dialysis start, death or 100 days, whichever came first. The primary outcome was difference in eGFR decline after AVA surgery compared with PDC. Decline in eGFR was estimated through linear mixed models with random intercept and slope, before and after surgery.

RESULTS

There were 435 AVA and 309 PDC patients. The AVA patients had higher eGFR (8.1 mL/min/1.73 m2 versus 7.0 mL/min/1.73 m2) and less rapid eGFR decline before surgery (-5.6 mL/min/1.73 m2/year compared with -6.7 mL/min/1.73 m2/year for PDC). We found no difference in eGFR decline after surgery in AVA patients compared with PDC patients [AVA progressed 0.26 (95% confidence interval -0.88 to 0.35) mL/min/1.73 m2/year faster after surgery compared with PDC].

CONCLUSIONS

There was no significant difference in eGFR decline after placement of an AVA compared with a PDC. Both forms of access were associated with reduced eGFR decline in our population. The need for dialysis remains the main determinant for timing of access surgery.

Association Between Midlife Physical Activity and Incident Kidney Disease: The Atherosclerosis Risk in Communities (ARIC) Study

RATIONALE & OBJECTIVE

Physical activity is associated with lower risk for cardiovascular disease, diabetes, and hypertension, which have shared risk factor profiles with chronic kidney disease (CKD). However, there are conflicting findings regarding the relationship between physical activity and CKD. The objective was to evaluate the association between physical activity and CKD development over long-term follow-up using the Atherosclerosis Risk in Communities (ARIC) Study.

STUDY DESIGN

Prospective cohort study.

SETTING & PARTICIPANTS

14,537 participants aged 45 to 64 years.

PREDICTORS

Baseline physical activity status was assessed using the modified Baecke Physical Activity Questionnaire at visit 1 (1987-1989) and categorized according to the 2018 Physical Activity Guidelines for Americans to group participants as inactive, insufficiently active, active, and highly active.

OUTCOMES

Incident CKD defined as estimated glomerular filtration rate (eGFR)<60mL/min/1.73m2 at follow-up and≥25% decline in eGFR relative to baseline, CKD-related hospitalization or death, or initiation of kidney replacement therapy.

ANALYTICAL APPROACH

Cox proportional hazards regression.

RESULTS

At baseline, 37.8%, 24.2%, 22.7%, and 15.3% of participants were classified as inactive, insufficiently active, active, and highly active, respectively. During a median follow-up of 24 years, 33.2% of participants developed CKD. After adjusting for age, sex, race-center, education, smoking status, diet quality, diabetes, coronary heart disease, hypertension, antihypertensive medication, body mass index, and baseline eGFR, higher categories of physical activity were associated with lower risk for CKD compared with the inactive group (HRs for insufficiently active, 0.95 [95% CI, 0.88-1.02]; active, 0.93 [95% CI, 0.86-1.01]; highly active, 0.89 [95% CI, 0.81-0.97]; P for trend = 0.007).

LIMITATIONS

Observational design and self-reported physical activity that was based on leisure time activity only. Due to low numbers, participants who were not Black or White were excluded.

CONCLUSIONS

Highly active participants had lower risk for developing CKD compared with inactive participants.

Different eGFR Decline Thresholds and Renal Effects of Canagliflozin: Data from the CANVAS Program

BACKGROUND

Traditionally, clinical trials evaluating effects of a new therapy with creatinine-based renal end points use doubling of serum creatinine (equivalent to a 57% eGFR reduction), requiring large sample sizes.

METHODS

To assess whether eGFR declines <57% could detect canagliflozin's effects on renal outcomes, we conducted a post hoc study comparing effects of canagliflozin versus placebo on composite renal outcomes using sustained 57%, 50%, 40%, or 30% eGFR reductions in conjunction with ESKD and renal death. Because canagliflozin causes an acute reversible hemodynamic decline in eGFR, we made estimates using all eGFR values as well as estimates that excluded early measures of eGFR influenced by the acute hemodynamic effect.

RESULTS

Among the 10,142 participants, 93 (0.9%), 161 (1.6%), 352 (3.5%), and 800 (7.9%) participants recorded renal outcomes on the basis of 57%, 50%, 40%, or 30% eGFR reduction, respectively, during a mean follow-up of 188 weeks. Compared with a 57% eGFR reduction (risk ratio [RR], 0.51; 95% confidence interval [95% CI], 0.34 to 0.77), the effect sizes were progressively attenuated when using 50% (RR, 0.61; 95% CI, 0.45 to 0.83), 40% (RR, 0.70; 95% CI, 0.57 to 0.86), or 30% (RR, 0.81; 95% CI, 0.71 to 0.93) eGFR reductions. In analyses that controlled for the acute hemodynamic fall in eGFR, effect sizes were comparable, regardless of whether a 57%, 50%, 40%, or 30% eGFR reduction was used. Estimated sample sizes for studies on the basis of lesser eGFR reductions were much reduced by controlling for this early hemodynamic effect.

CONCLUSIONS

Declines in eGFR <57% may provide robust estimates of canagliflozin's effects on renal outcomes if the analysis controls for the drug's acute hemodynamic effect.

CLINICAL TRIAL REGISTRY NAME AND REGISTRATION NUMBER

CANagliflozin cardioVascular Assessment Study (CANVAS), NCT01032629 and CANVAS-R, NCT01989754.

Dietary Patterns Based on Estimated Glomerular Filtration Rate and Kidney Function Decline in the General Population: The Lifelines Cohort Study

No specific dietary patterns have been established that are linked with loss of kidney function. We aimed to identify an estimated glomerular filtration rate-based dietary pattern (eGFR-DP) and to evaluate its association with eGFR decline and chronic kidney disease (CKD) incidence in the general population. We included 78,335 participants from the Lifelines cohort in the Northern Netherlands. All participants had an eGFR >60 mL/min/1.73 m² at baseline and completed a second visit five years later. The eGFR-DP was constructed at baseline using a 110-item food frequency questionnaire by reduced rank regression, stratified by sex. Logistic regression was performed to evaluated the association between the eGFR-DP score and either a ≥20% eGFR decline or incident CKD. Among women, eGFR-DP were characterized by high consumption of egg, cheese, and legumes and low consumption of sweets, white meat, and commercially prepared dishes. In men, eGFR-DP were characterized by high consumption of cheese, bread, milk, fruits, vegetables, and beer and low consumption of white and red meat. A higher eGFR-DP score was associated with a lower risk of a ≥20% eGFR decline (OR 4th vs. 1st quartile, women: 0.79 [95% CI: 0.73-0.87]; men: 0.67 [0.59-0.76]). The association between the eGFR-DP score and CKD incidence was lost upon adjustment for baseline eGFR. Our results provide support for dietary interventions to prevent kidney function decline in the general population.

Factors Associated with a Large Decline in Renal Function or Progression to Renal Insufficiency in Hospitalized Atrial Fibrillation Patients with Early-Stage CKD

Clinicians must consider renal function when administering anticoagulants for atrial fibrillation (AF). Determination of risk factors for renal function decline may enable identification of patients who require closer monitoring. We investigated the characteristics associated with renal function decline in patients with AF. The study cohort consisted of 631 AF patients who had at least one readmission during the follow-up period and stages 1-3 chronic kidney disease (CKD). The primary outcome measure was large renal function decline (≥30% decrease from baseline estimated glomerular filtration rate [eGFR]). The secondary outcome measure was a final eGFR < 60 mL/minute/1.73 m² for those with a baseline eGFR above this level. The mean eGFR was 74.4 ± 18.5 mL/minute/1.73 m², and the mean follow-up time was 30.2 ± 13.2 months. The primary outcome occurred in 155 patients (24.6%) and was associated with congestive heart failure (CHF), proteinuria, type of AF, and left atrial diameter (LAD) ≥ 45 mm. Among 478 patients with a baseline eGFR ≥ 60 mL/minute/1.73 m², 137 (28.7%) progressed to renal failure (eGFR < 60 mL/minute/1.73 m²). A decreasing eGFR was associated with age ≥ 75 years, CHF, lower baseline eGFR, and LAD ≥ 45 mm. CHF, proteinuria, type of AF, and LAD ≥ 45 mm were associated with eGFR decline ≥ 30% in AF patients with CKD stages 1-3. Advanced age, CHF, lower baseline eGFR, and LAD ≥ 45 mm were associated with progression to renal insufficiency. These results should be considered when identifying patients who require more frequent monitoring of eGFR.

Plasma Soluble Urokinase Plasminogen Activator Receptor (suPAR) and CKD Progression in Children

RATIONALE & OBJECTIVE

Soluble urokinase plasminogen activator receptor (suPAR) is a novel biomarker associated with incident chronic kidney disease (CKD) and has been identified as an independent risk factor for CKD progression in children, although these findings remain preliminary, limited to a single point in time, and unreplicated in pediatric cohorts.

STUDY DESIGN

Prospective longitudinal cohort study.

SETTING & PARTICIPANTS

565 participants aged 1 to 16 years enrolled in the Chronic Kidney Disease in Children (CKiD) Study.

EXPOSURE

Plasma suPAR levels, categorized by quartiles, measured at study entry and a 6-month follow-up interval.

OUTCOME

CKD progression, defined as the initiation of kidney replacement therapy (dialysis or transplantation) or >50% decline in estimated glomerular filtrate rate (eGFR).

ANALYTIC APPROACH

Associations between plasma suPAR quartiles and risk for CKD progression were estimated using lognormal survival models, adjusting for potential confounders.

RESULTS

Participants in the highest suPAR quartile experienced 54% faster progression compared with the lowest quartile after adjustment for demographic and traditional CKD risk factors (P < 0.001). Addition of eGFR to the model attenuated the risk, although those in the highest quartile experienced 33% faster progression compared with the lowest quartile (P = 0.008). Plasma suPAR levels showed little change over 6 months.

LIMITATIONS

Potential for residual confounding, reliance on observational data, relatively fewer patients with higher eGFRs for subgroup analysis.

CONCLUSIONS

Higher suPAR levels are associated with shorter time to kidney replacement therapy or halving of eGFR in children with CKD. This association is attenuated slightly with inclusion of eGFR in regression modeling but remains a significant association for participants with the highest suPAR levels.

Sex Differences in the Progression of CKD Among Older Patients: Pooled Analysis of 4 Cohort Studies

RATIONALE & OBJECTIVE

Data for the association of sex with chronic kidney disease (CKD) progression are conflicting, a relationship this study sought to examine.

STUDY DESIGN

Pooled analysis of 4 Italian observational cohort studies.

SETTING & PARTICIPANTS

1,311 older men and 1,024 older women with estimated glomerular filtration rate (eGFR)<45mL/min/1.73m² followed up in renal clinics.

PREDICTOR

Sex.

OUTCOMES

End-stage kidney disease (ESKD), defined as maintenance dialysis or kidney transplantation, as the primary outcome; all-cause mortality and eGFR decline as secondary outcomes.

ANALYTICAL APPROACH

Cox proportional hazard analysis to estimate the relative risk for ESKD and mortality and linear mixed models to estimate the rate of eGFR decline.

RESULTS

Age, systolic blood pressure, and use of renin-angiotensin system inhibitors were similar in men and women. Baseline eGFRs were 27.6±10.2 in men and 26.0±10.6mL/min/1.73m² in women (P<0.001), while median proteinuria was lower in women (protein excretion, 0.45 [IQR, 0.14-1.10] g/d) compared with men (0.69 [IQR 0.19-1.60] g/d; P<0.001). During a median follow-up of 4.2 years, 757 developed ESKD (59.4% men) and 471 died (58.4% men). The adjusted risks for ESKD and mortality were higher in men (HRs of 1.50 [95% CI, 1.28-1.77] and 1.30 [95% CI, 1.06-1.60], respectively). This finding was consistent across CKD stages. We observed a significant interaction between sex and proteinuria, with the risk for ESKD in men being significantly greater than for women at a level of proteinuria of ∼0.5g/d or greater. The slope of decline in eGFR was steeper in men (-2.09; 95% CI, -2.21 to-1.97mL/min/1.73m² per year) than in women (-1.79; 95% CI, -1.92 to-1.66mL/min/1.73m² per year; P<0.001). Although sex differences in eGFR decline were not different across CKD stages (P=0.3), the difference in slopes between men and women was progressively larger with proteinuria >0.5g/d (P = 0.04).

LIMITATIONS

Residual confounding; only whites were included.

CONCLUSIONS

Excess renal risk in men may, at least in part, be related to higher levels of proteinuria in men compared with women.

Low Birth Weight and Kidney Function in Middle-Aged Men and Women: The Netherlands Epidemiology of Obesity Study

RATIONALE & OBJECTIVE

Chronic kidney disease (CKD), defined as estimated glomerular filtration rate (eGFR)<60mL/min/1.73m², is a risk factor for cardiovascular morbidity and mortality. Little is known about low birth weight and risk for CKD in middle-aged adults in the general population. We estimated the causal association between birth weight and eGFR in a Dutch cohort of middle-aged men and women.

STUDY DESIGN

Retrospective cohort study.

SETTING & PARTICIPANTS

6,671 participants in the Netherlands Epidemiology of Obesity (NEO) Study. Replication study using data for 133,814 participants studied by the CKDGen consortium.

EXPOSURE

Birth weight was self-reported and also based on an instrumental variable, 59 birth weight-associated genetic variants, derived from an independent data source.

OUTCOME

eGFR at the age of 45 to 65 years.

ANALYTICAL APPROACH

We assessed the association between self-reported birth weight and eGFR in the NEO Study using multivariable linear regression, adjusted for age, sex, education, smoking, and alcohol use. The effect of the instrument on eGFR was estimated using separate 2-sample Mendelian randomization analyses: one using individual data from the NEO cohort and one using summary data from the CKDGen consortium.

RESULTS

At baseline, mean eGFR was 86±12.4 (SD) mL/min/1.73m². After multivariable adjustment, self-reported birth weight was not associated with kidney function in middle age. Two-sample Mendelian randomization analysis showed that in the NEO cohort, for each 500-g lower birth weight defined using genetic variants, there was a 3.7 (95% CI, 0.5-6.9)-mL/min/1.73m² lower eGFR at the age of 45 to 65 years. However, using CKDGen summary-level data, there was a smaller nonsignificant relationship between birth weight and eGFR.

LIMITATIONS

Birth weight was self-reported.

CONCLUSIONS

Lower birth weight defined using genetic variants was associated with lower eGFRs in Dutch middle-aged adults. However, this finding was not replicated within the CKDGen consortium.

Progressive Decline in Estimated GFR in Patients With Sickle Cell Disease: An Observational Cohort Study

RATIONALE & OBJECTIVE

Progression of chronic kidney disease (CKD) in sickle cell disease (SCD) and its risk factors remain poorly defined. We identified characteristics associated with CKD as well as decline in estimated glomerular filtration rate (eGFR) and presence of proteinuria over time in adults with SCD.

STUDY DESIGN

Retrospective observational study.

SETTING & PARTICIPANTS

Patients with SCD 18 years or older in a single center from 2004 to 2013.

PREDICTORS

Baseline clinical and laboratory measures, comorbid conditions, SCD-related complications, relevant treatments, and severity of genotypes defined as severe (homozygous SCD [HbSS]/sickle-β⁰-thalassemia [HbSβ⁰]) or mild (hemoglobin SC disease [HbSC]/sickle-β⁺-thalassemia [HbSβ⁺]-thalassemia).

OUTCOMES

Presence at baseline of CKD, defined here as eGFR<90mL/min/1.73m² or proteinuria (≥1+) on urinalysis or current kidney transplant or dialysis therapy; change in eGFR; and presence of proteinuria over time.

ANALYTICAL APPROACH

Logistic regression for baseline CKD. Linear mixed-effects model for eGFR decline and generalized linear mixed-effects model for proteinuria during the study period evaluating for interaction with time. Stratified by genotype severity.

RESULTS

Among 427 patients, 331 had 2 or more measurements of creatinine. During a median follow-up of 4.01 (interquartile range, 1.66-7.19) years, annual eGFR decline was 2.05mL/min/1.73m² for severe genotypes (P<0.001) and 1.16mL/min/1.73m² (P=0.02) for mild genotypes. At baseline, 21.4% of patients with severe genotypes had CKD versus 17.2% of those with mild genotypes. For severe genotypes, angiotensin-converting enzyme-inhibitor/angiotensin receptor blocker use (OR, 6.10; 95% CI, 2.03-18.29; P=0.001) and avascular necrosis (OR, 0.40; 95% CI, 0.16-0.97; P=0.04) were associated with baseline CKD. Among those with mild genotypes, higher hemoglobin level was associated with lower probability of CKD (OR per 1-g/dL greater hemoglobin level, 0.63; 95% CI, 0.43-0.93; P=0.02). Rate of eGFR decline was inversely related to hemoglobin level (β = 0.46 [SE, 0.23]; P=0.04) within the severe genotype subgroup. No factors were identified to be associated with proteinuria over time.

LIMITATIONS

Retrospective observational study, limited direct measures of albuminuria.

CONCLUSIONS

Patients with SCD exhibit rapid decline in eGFR over time. Decline in eGFR is associated with markers of disease severity and associated comorbid conditions.

Neighborhood Social Context and Kidney Function Over Time: The Multi-Ethnic Study of Atherosclerosis

RATIONALE & OBJECTIVE

Although socioeconomic status has been associated with chronic kidney disease (CKD), little is known about its relationship to residential neighborhood context.

STUDY DESIGN

Secondary analysis of the Multi-Ethnic Study of Atherosclerosis (MESA), a prospective cohort study designed to investigate the development and progression of subclinical cardiovascular disease.

SETTING & PARTICIPANTS

6,814 men and women who were between 45 and 84 years of age and free of cardiovascular disease were recruited between 2000 and 2002 from Baltimore, MD; Chicago, IL; Forsyth County, NC; Los Angeles, CA; New York, NY; and St. Paul, MN.

EXPOSURES

A composite neighborhood problem score (calculated based on 7 participant-reported domains at study entry: adequacy of food sources, availability of parks/playground, noise, sidewalks, traffic, trash and litter, and violence) and a social cohesion score (calculated based on 5 participant-reported attributes of people in their neighborhood: close knit; get along; willing to help neighbors; trustworthy; and share values).

OUTCOMES

Estimated glomerular filtration rate (eGFR; calculated using the CKD-EPI [CKD Epidemiology Collaboration] creatinine-cystatin C equation) and an indicator of eGFR decline > 30% since study entry using follow-up eGFR quantified at 4 examinations: 2000 to 2002, 2004 to 2005, 2005 to 2007, and 2010 to 2011.

ANALYTICAL APPROACH

Associations between each neighborhood measure (in separate models) and eGFR decline > 30% from baseline and annualized eGFR change were estimated using Cox proportional hazards and linear mixed regression models, respectively, adjusting for potential confounders.

RESULTS

While neighborhood social context differs by race/ethnicity, neither neighborhood problems nor social cohesion was independently associated with eGFR decline after adjustment for confounders.

LIMITATIONS

Incomplete capture of the early stages of eGFR decline, reliance on observational data, limited variation in neighborhood measures, and the potential for residual confounding.

CONCLUSIONS

Although we showed no independent association between neighborhood context and eGFR decline, it is associated with many CKD risk factors and further work is needed to clarify whether it has an independent role in CKD.

Serum sodium concentration and the progression of established chronic kidney disease

Background

Higher serum sodium concentration has been reported to be a risk factor for the development of incident chronic kidney disease (CKD), but its relationship with the progression of established CKD has not been investigated. We hypothesised that increased serum sodium concentration is a risk factor for estimated glomerular filtration rate (eGFR) decline in CKD.

Methods

This was a retrospective cohort study using data collected over a 6-year period, with baseline data obtained during the first 2 years. We included patients known to our renal service who had had a minimum of three blood tests every 2 years and an eGFR of < 60 mL/min/1.73 m² at baseline. Exclusion criteria were renal replacement therapy, diabetes mellitus, heart failure and decompensated liver disease. A multiple linear regression model investigated the relationship between baseline serum sodium and eGFR decline after adjustment for confounding factors.

Results

7418 blood results from 326 patients were included. There was no relationship between serum sodium concentration and estimated glomerular filtration rate at baseline. After multivariable adjustment, a 1 mmol/L increase in baseline serum sodium was associated with a 1.5 mL/min/1.73 m² decline in eGFR during the study period (95% CI 0.9, 2.0). A reduction in eGFR was not associated with significant changes in serum sodium concentration over 6 years.

Conclusion

Higher serum sodium concentration is associated with the progression of CKD, independently of other established risk factors. Conversely, significant alterations in serum sodium concentration do not occur with declining kidney function.

Effects of Intensive Blood Pressure Lowering on Kidney Tubule Injury in CKD: A Longitudinal Subgroup Analysis in SPRINT

BACKGROUND

Random assignment to the intensive systolic blood pressure (SBP) arm (<120mmHg) in the Systolic Blood Pressure Intervention Trial (SPRINT) resulted in more rapid declines in estimated glomerular filtration rates (eGFRs) than in the standard arm (SBP<140mmHg). Whether this change reflects hemodynamic effects or accelerated intrinsic kidney damage is unknown.

STUDY DESIGN

Longitudinal subgroup analysis of clinical trial participants.

SETTINGS & PARTICIPANTS

Random sample of SPRINT participants with prevalent chronic kidney disease (CKD) defined as eGFR<60mL/min/1.73m² by the CKD-EPI (CKD Epidemiology Collaboration) creatinine-cystatin C equation at baseline.

OUTCOMES & MEASUREMENTS

Urine biomarkers of tubule function (β₂-microglobulin [B2M], α₁-microglobulin [A1M]), and uromodulin), injury (interleukin 18, kidney injury molecule 1, and neutrophil gelatinase-associated lipocalin), inflammation (monocyte chemoattractant protein 1), and repair (human cartilage glycoprotein 40) at baseline, year 1, and year 4. Biomarkers were indexed to urine creatinine concentration and changes between arms were evaluated using mixed-effects linear models and an intention-to-treat approach.

RESULTS

978 SPRINT participants (519 in the intensive and 459 in the standard arm) with prevalent CKD were included. Mean age was 72±9 years and eGFR was 46.1±9.4mL/min/1.73m² at baseline. Clinical characteristics, eGFR, urinary albumin-creatinine ratio, and all 8 biomarker values were similar across arms at baseline. Compared to the standard arm, eGFR was lower by 2.9 and 3.3mL/min/1.73m² in the intensive arm at year 1 and year 4. None of the 8 tubule marker levels was higher in the intensive arm compared to the standard arm at year 1 or year 4. Two tubule function markers (B2M and A1M) were 29% (95% CI, 10%-43%) and 24% (95% CI, 10%-36%) lower at year 1 in the intensive versus standard arm, respectively.

LIMITATIONS

Exclusion of persons with diabetes, and few participants had advanced CKD.

CONCLUSIONS

Among participants with CKD in SPRINT, random assignment to the intensive SBP arm did not increase any levels of 8 urine biomarkers of tubule cell damage despite loss of eGFR. These findings support the hypothesis that eGFR declines in the intensive arm of SPRINT predominantly reflect hemodynamic changes rather than intrinsic damage to kidney tubule cells.

Effect of Intensive Blood Pressure Lowering on Kidney Tubule Injury: Findings From the ACCORD Trial Study Participants

RATIONALE & OBJECTIVE

Random assignment to intensive blood pressure (BP) lowering (systolic BP<120mmHg) compared to a less intensive BP target (systolic BP<140mmHg) in the Action to Control Cardiovascular Risk in Diabetes BP (ACCORD-BP) trial resulted in a more rapid decline in estimated glomerular filtration rate (eGFR). Whether this reflects hemodynamic effects or intrinsic kidney damage is unknown.

STUDY DESIGN

Longitudinal analysis of a subgroup of clinical trial participants.

SETTINGS & PARTICIPANTS

A subgroup of 529 participants in ACCORD-BP.

EXPOSURES

Urine biomarkers of tubular injury (kidney injury molecule 1, interleukin 18 [IL-18]), repair (human cartilage glycoprotein 39 [YKL-40]), and inflammation (monocyte chemoattractant protein 1) at baseline and year 2.

OUTCOMES

Changes in eGFR from baseline to 2 years.

ANALYTICAL APPROACH

We compared changes in biomarker levels and eGFRs across participants treated to an intensive versus less intensive BP goal using analysis of covariance.

RESULTS

Of 529 participants, 260 had been randomly assigned to the intensive and 269 to the standard BP arm. Mean age was 62±6.5 years and eGFR was 90mL/min/1.73m². Baseline clinical characteristics, eGFRs, urinary albumin-creatinine ratios (ACRs), and urinary biomarker levels were similar across BP treatment groups. Compared to less intensive BP treatment, eGFR was 9.2mL/min/1.73m² lower in the intensive BP treatment group at year 2. Despite the eGFR reduction, within this treatment group, ACR was 30% lower and 4 urinary biomarker levels were unchanged or lower at year 2. Also within this group, participants with the largest declines in eGFRs had greater reductions in urinary IL-18 and YKL-40 levels. In a subgroup analysis of participants developing incident chronic kidney disease (sustained 30% decline and eGFR<60mL/min/1.73m²; n=77), neither ACR nor 4 biomarker levels increased in the intensive treatment group, whereas the level of 1 biomarker, IL-18, increased in the less intensive treatment group.

LIMITATIONS

Few participants with advanced baseline chronic kidney disease. Comparisons across treatment groups do not represent comparisons of treatment arms created solely through randomization.

CONCLUSIONS

Among a subset of ACCORD-BP trial participants, intensive BP control was associated with reductions in eGFRs, but not with an increase in injury marker levels. These findings support that eGFR decline observed with intensive BP goals in ACCORD participants may predominantly reflect hemodynamic alterations.

Decline in Kidney Function among Apparently Healthy Young Adults at Risk of Mesoamerican Nephropathy

Background Epidemic levels of CKD of undetermined cause, termed Mesoamerican nephropathy in Central America, have been found in low- and middle-income countries. We investigated the natural history of, and factors associated with, loss of kidney function in a population at high risk for this disease.Methods We conducted a 2-year prospective, longitudinal study with follow-up every 6 months in nine rural communities in northwestern Nicaragua and included all men (n=263) and a random sample of women (n=87) ages 18-30 years old without self-reported CKD, diabetes, or hypertension. We used growth mixture modeling to identify subgroups of eGFR trajectory and weighted multinomial logistic regression to examine associations with proposed risk factors.Results Among men, we identified three subpopulations of eGFR trajectory (mean baseline eGFR; mean eGFR change over follow-up): 81% remained stable (116 ml/min per 1.73 m2; -0.6 ml/min per 1.73 m2 per year), 9.5% experienced rapid decline despite normal baseline function (112 ml/min per 1.73 m2; -18.2 ml/min per 1.73 m2 per year), and 9.5% had baseline dysfunction (58 ml/min per 1.73 m2; -3.8 ml/min per 1.73 m2 per year). Among women: 96.6% remained stable (121 ml/min per 1.73 m2; -0.6 ml/min per 1.73 m2 per year), and 3.4% experienced rapid decline (132 ml/min per 1.73 m2; -14.6 ml/min per 1.73 m2 per year; n=3 women). Among men, outdoor and agricultural work and lack of shade availability during work breaks, reported at baseline, were associated with rapid decline.Conclusions Although Mesoamerican nephropathy is associated with agricultural work, other factors may also contribute to this disease.

Risk of Progression of Nonalbuminuric CKD to End-Stage Kidney Disease in People With Diabetes: The CRIC (Chronic Renal Insufficiency Cohort) Study

BACKGROUND

Reduced glomerular filtration rate (GFR) in the absence of albuminuria is a common manifestation of chronic kidney disease (CKD) in diabetes. However, the frequency with which it progresses to end-stage kidney disease (ESKD) is unknown.

STUDY DESIGN

Multicenter prospective cohort study.

SETTING & PARTICIPANTS

We included 1,908 participants with diabetes and reduced GFR enrolled in the Chronic Renal Insufficiency Cohort (CRIC) Study in the United States.

PREDICTORS

Urinary albumin and protein excretion.

OUTCOMES

Incident ESKD, CKD progression (ESKD or ≥50% reduction in estimated GFR [eGFR] from baseline), and annual rate of decline in kidney function.

MEASUREMENTS

ESKD was ascertained by self-report and by linkage to the US Renal Data System. We used Cox proportional hazards modeling to estimate the association of albuminuria and proteinuria with incident ESKD or CKD progression and linear mixed-effects models to assess differences in eGFR slopes among those with and without albuminuria.

RESULTS

Mean eGFR at baseline was 41.2mL/min/1.73m². Normal or mildly increased 24-hour urinary albumin excretion (<30mg/d) at baseline was present in 28% of participants, but in only 5% of those progressing to ESKD. For those with baseline normal or mildly increased albuminuria, moderately increased albuminuria (albumin excretion, 30-299mg/d), and 2 levels of severely increased albuminuria (albumin excretion, 300-999 and ≥1,000mg/d): crude rates of ESKD were 7.4, 34.8, 78.7, and 178.7 per 1,000 person-years, respectively; CKD progression rates were 17.0, 61.4, 130.5, and 295.1 per 1,000 person-years, respectively; and annual rates of eGFR decline were -0.17, -1.35, -2.74, and -4.69mL/min/1.73m², respectively.

LIMITATIONS

We were unable to compare the results with healthy controls.

CONCLUSIONS

In people with diabetes with reduced eGFRs, the absence of albuminuria or proteinuria is common and carries a much lower risk for ESKD, CKD progression, or rapid decline in eGFR compared with those with albuminuria or proteinuria. The rate of eGFR decline in normoalbuminuric CKD was similar to that reported for the general diabetic population.

Association between vascular access creation and deceleration of estimated glomerular filtration rate decline in late-stage chronic kidney disease patients transitioning to end-stage renal disease

Background

Prior studies have suggested that arteriovenous fistula (AVF) or graft (AVG) creation may be associated with slowing of estimated glomerular filtration rate (eGFR) decline. It is unclear if this is attributable to the physiological benefits of a mature access on systemic circulation versus confounding factors.

Methods

We examined a nationwide cohort of 3026 US veterans with advanced chronic kidney disease (CKD) transitioning to dialysis between 2007 and 2011 who had a pre-dialysis AVF/AVG and had at least three outpatient eGFR measurements both before and after AVF/AVG creation. Slopes of eGFR were estimated using mixed-effects models adjusted for fixed and time-dependent confounders, and compared separately for the pre- and post-AVF/AVG period overall and in patients stratified by AVF/AVG maturation. In all, 3514 patients without AVF/AVG who started dialysis with a catheter served as comparators, using an arbitrary 6-month index date before dialysis initiation to assess change in eGFR slopes.

Results

Of the 3026 patients with AVF/AVG (mean age 67 years, 98% male, 75% diabetic), 71% had a mature AVF/AVG at dialysis initiation. eGFR decline accelerated in the last 6 months prior to dialysis in patients with a catheter (median, from -6.0 to -16.3 mL/min/1.73 m2/year, P < 0.001), while a significant deceleration of eGFR decline was seen after vascular access creation in those with AVF/AVG (median, from -5.6 to -4.1 mL/min/1.73 m2/year, P < 0.001). Findings were independent of AVF/AVG maturation status and were robust in adjusted models.

Conclusions

The creation of pre-dialysis AVF/AVG appears to be associated with eGFR slope deceleration and, consequently, may delay the onset of dialysis initiation in advanced CKD patients.

Uric Acid and the Risks of Kidney Failure and Death in Individuals With CKD

BACKGROUND

Serum uric acid concentrations increase in chronic kidney disease (CKD) and may lead to tubular injury, endothelial dysfunction, oxidative stress, and intrarenal inflammation. Whether uric acid concentrations are associated with kidney failure and death in CKD is unknown.

STUDY DESIGN

Prospective observational cohort study.

SETTINGS & PARTICIPANTS

3,885 individuals with CKD stages 2 to 4 enrolled in the Chronic Renal Insufficiency Cohort (CRIC) between June 2003 and September 2008 and followed up through March 2013.

PREDICTOR

Baseline uric acid concentrations.

OUTCOMES

Kidney failure (initiation of dialysis therapy or transplantation) and all-cause mortality.

RESULTS

During a median follow-up of 7.9 years, 885 participants progressed to kidney failure and 789 participants died. After adjustment for demographic, cardiovascular, and kidney-specific covariates, higher uric acid concentrations were independently associated with risk for kidney failure in participants with estimated glomerular filtration rates (eGFRs) ≥ 45mL/min/1.73m² (adjusted HR per 1-standard deviation greater baseline uric acid, 1.40; 95% CI, 1.12-1.75), but not in those with eGFRs<30mL/min/1.73m². There was a nominally higher HR in participants with eGFRs of 30 to 44mL/min/1.73m² (adjusted HR, 1.13; 95% CI, 0.99-1.29), but this did not reach statistical significance. The relationship between uric acid concentration and all-cause mortality was J-shaped (P=0.007).

LIMITATIONS

Potential residual confounding through unavailable confounders; lack of follow-up measurements to adjust for changes in uric acid concentrations over time.

CONCLUSIONS

Uric acid concentration is an independent risk factor for kidney failure in earlier stages of CKD and has a J-shaped relationship with all-cause mortality in CKD. Adequately powered randomized placebo-controlled trials in CKD are needed to test whether urate lowering may prove to be an effective approach to prevent complications and progression of CKD.

Association between dipstick hematuria and decline in estimated glomerular filtration rate among Japanese patients with type 2 diabetes: A prospective cohort study [Diabetes Distress and Care Registry at Tenri (DDCRT 14)]

AIMS

To assess the association between dipstick hematuria and estimated glomerular filtration rate (eGFR) decline in Japanese patients with type 2 diabetes.

METHODS

Longitudinal data were obtained from 3068 Japanese patients with type 2 diabetes. To assess the independent association between dipstick hematuria and eGFR decline, we used Cox proportional hazard model adjusted for potential confounders.

RESULTS

Median follow-up period was 699.7days. Mean age, body mass index (BMI), and HbA1c level were 65.7years, 24.6kg/m², and 7.5% (58.1mmol/mol), respectively. Positive dipstick hematuria was significantly associated with baseline eGFR and severity of albuminuria (p<0.001). The multivariable-adjusted hazard ratio for eGFR decline in patients with dipstick hematuria compared with those without dipstick hematuria was 2.19 [95% confidence interval (CI): 1.22-3.91]; this association remained significant even after the exclusion of patients who did not have diabetic retinopathy (hazard ratio: 2.39; 95% CI: 1.13-5.04).

CONCLUSION

Positive dipstick hematuria was associated with severity of albuminuria and renal function. A significant association was found between dipstick hematuria and increased risk of eGFR decline among patients with type 2 diabetes. Therefore, our results suggest that dipstick hematuria is perhaps indicative of more severe diabetic nephropathy.

Association between Monocyte Count and Risk of Incident CKD and Progression to ESRD

BACKGROUND AND OBJECTIVES

Experimental evidence suggests a role for monocytes in the biology of kidney disease progression; however, whether monocyte count is associated with risk of incident CKD, CKD progression, and ESRD has not been examined in large epidemiologic studies.

DESIGN, SETTINGS, PARTICIPANTS, & MEASUREMENTS

We built a longitudinal observational cohort of 1,594,700 United States veterans with at least one eGFR during fiscal year 2004 (date of last eGFR during this period designated time zero) and no prior history of ESRD, dialysis, or kidney transplant. Cohort participants were followed until September 30, 2013 or death. Monocyte count closest to and before time zero was categorized in quartiles: quartile 1, >0.00 to ≤0.40 thousand cells per cubic millimeter (k/cmm); quartile 2, >0.40 to ≤0.55 k/cmm; quartile 3, >0.55 to ≤0.70 k/cmm; and quartile 4, >0.70 k/cmm. Survival models were built to examine the association between monocyte count and risk of incident eGFR<60 ml/min per 1.73 m2, risk of incident CKD, and risk of CKD progression defined as doubling of serum creatinine, eGFR decline ≥30%, or the composite outcome of ESRD, dialysis, or renal transplantation.

RESULTS

Over a median follow-up of 9.2 years (interquartile range, 8.3-9.4); in adjusted survival models, there was a graded association between monocyte counts and risk of renal outcomes. Compared with quartile 1, quartile 4 was associated with higher risk of incident eGFR<60 ml/min per 1.73 m2 (hazard ratio, 1.13; 95% confidence interval, 1.12 to 1.14) and risk of incident CKD (hazard ratio, 1.15; 95% confidence interval, 1.13 to 1.16). Quartile 4 was associated with higher risk of doubling of serum creatinine (hazard ratio, 1.22; 95% confidence interval, 1.20 to 1.24), ≥30% eGFR decline (hazard ratio, 1.18; 95% confidence interval, 1.17 to 1.19), and the composite renal end point (hazard ratio, 1.19; 95% confidence interval, 1.16 to 1.22). Cubic spline analyses of the relationship between monocyte count levels and renal outcomes showed a linear relationship, in which risk was higher with higher monocyte count. Results were robust to changes in sensitivity analyses.

CONCLUSIONS

Our results show a significant association between higher monocyte count and risks of incident CKD and CKD progression to ESRD.

Echocardiographic Measures and Estimated GFR Decline Among African Americans: The Jackson Heart Study

BACKGROUND

Cardiac structural abnormalities, common in African Americans, are associated with adverse clinical outcomes. Associations between echocardiography-measured subclinical heart failure and kidney function decline are unknown and may identify novel risk factors for kidney disease in this population.

STUDY DESIGN

Prospective cohort study.

SETTING & PARTICIPANTS

2,418 Jackson Heart Study participants with baseline echocardiograms and longitudinal measures of estimated glomerular filtration rate (eGFR) calculated from the CKD-EPI creatinine equation. 2,219 participants had baseline eGFRs≥60mL/min/1.73m².

PREDICTORS

Left ventricular mass (LVM) and ejection fraction (LVEF) and pulmonary artery systolic pressure (PASP) quantified from baseline echocardiograms.

OUTCOMES

Primary outcome was >30% eGFR decline or progression to end-stage renal disease (ESRD; need for dialysis therapy) over a mean of 8 years. Secondary outcome, eGFR<60mL/min/1.73m² or progression to ESRD and eGFR decline >1mL/min/1.73m² per year among those with baseline eGFRs≥60mL/min/1.73m².

MEASUREMENTS

Logistic regression models, adjusted for demographics, physical characteristics, comorbid conditions, and medication use.

RESULTS

Mean age was 52.2±11.9 (SD) years, 37% of participants were men; mean baseline eGFR was 87.3±17.3mL/min/1.73m². The primary and secondary outcomes occurred in 148 (6.1%) and 162 (7.1%) participants, respectively. In unadjusted models, every 25-g greater LVM was significantly associated with greater odds of eGFR decline > 30% or ESRD (OR, 1.38; 95% CI, 1.26-1.51) and incident eGFR<60mL/min/1.73m² or ESRD (OR, 1.30; 95% CI, 1.20-1.42); only the former remained statistically significant after adjustment. There was no association of LVEF or PASP with either eGFR decline > 30% or ESRD (LVEF: adjusted OR, 0.95 [95% CI, 0.84-1.07]; PASP: adjusted OR, 0.98 [95% CI, 0.87-1.11]) or incident eGFR<60mL/min/1.73m² or ESRD (LVEF: adjusted OR, 0.98 [95% CI, 0.86-1.11]; PASP: adjusted OR, 1.05 [95% CI, 0.94-1.18]) in multivariable models.

LIMITATIONS

No midstudy creatinine measurement at examination 2.

CONCLUSIONS

Greater LVM was significantly associated with eGFR decline > 30% or ESRD among African Americans in a community-based cohort. Treating and reversing elevated LVM may reduce the burden and progression of kidney disease in this high-risk population.

Investigation of Metabolic Factors Associated with eGFR Decline Over 1 Year in a Japanese Population without CKD

Aim: Early intervention before the progression of chronic kidney disease (CKD) is essential to prevent end-stage renal disease (ESRD) and cardiovascular complications. This study evaluated the correlation between metabolic and lifestyle-related factors and the decline of estimated glomerular filtration rate (eGFR) over 1 year in a Japanese population without CKD.

Methods: Subjects who received two consecutive annual health checkups from 2013 to 2015 were involved. Factors associated with eGFR decline were identified using multiple regression models.

Results: A total of 2531 subjects aged 58.9 ± 11.7 years old were included in this study. Baseline levels of HDL-C and ApoA1 correlated with the eGFR decline over 1 year defined as eGFR reduction rate of 15% or more and/or eGFR at the next year < 60 ml/min/m² (odds ratio (OR) 0.87 (per 10 mg/dl); 95% CI, 0.80–0.94; p = 0.0012, 0.90 (per 10 mg/dl); 0.86–0.96; p = 0.0004, respectively). A U-shaped relationship between the eGFR decline and HDL-C or ApoA1 levels was not observed in non-CKD population of this study. Metabolic syndrome was significantly associated with eGFR decline (OR 1.32; 1.04–1.67; p = 0.0205), although obesity-related factors did not show a significant correlation with eGFR decline over 1 year.

Conclusion: Low HDL-C and ApoA1 levels significantly correlated with eGFR decline in a short period of 1 year. Metabolic syndrome also showed a significant association with eGFR decline. This study suggests the importance of hypertension and low HDL-C in the metabolic syndrome effect on eGFR decline rather than obesity in non-CKD population.

The association of urinary sodium excretion and the need for renal replacement therapy in advanced chronic kidney disease: a cohort study

Background

Restriction of dietary sodium is routinely recommended for patients with chronic kidney disease (CKD). Whether or not sodium intake is associated with the progression of CKD and mortality remains controversial. We evaluated the association of urinary sodium excretion (as a surrogate for sodium intake) on the need for renal replacement therapy and mortality in patients with advanced CKD.

Methods

We conducted a retrospective study of patients followed at a CKD clinic of a tertiary care hospital from January 2010 to December 2012. Adult patients with advanced CKD (estimated glomerular filtration rate (eGFR) <30 ml/min/1.73 m²) were included. Using a time-to-event analysis, we examined the association of urinary sodium excretion as a continuous and also as a categorical variable (categorized as low sodium diet - LSD (<100 mEq/day), medium sodium diet - MSD (100–150 mEq/day), and high sodium diet - HSD (>150 mEq/day) and the outcomes of interest. The primary outcome was defined as composite of progression to end-stage renal disease requiring any type of renal replacement therapy and mortality. The secondary outcome was change in eGFR/year.

Results

341 patients (82 LSD, 116 MSD and 143 HSD) were included in the study (mean follow up of 1.5 years) with a mean eGFR decline of 2.7 ml/min/1.73 m²/year. 105 patients (31 %) required renal replacement therapy and 10 (3 %) died. There was no association between urinary sodium excretion and change in the eGFR or need for renal replacement therapy and mortality in crude or adjusted models (unadjusted HR 1.002; 95%CI 1.000–1.004, adjusted HR 1.001; 95%CI 0.998–1.004).

Conclusion

In patients with advanced CKD (eGFR < 30 ml/min/1.73 m²), sodium intake does not appear to impact the progression of CKD to end-stage renal disease; however, more definitive studies are needed.

Electronic supplementary material

The online version of this article (doi:10.1186/s12882-016-0338-z) contains supplementary material, which is available to authorized users.

Geographic Variation and US County Characteristics Associated With Rapid Kidney Function Decline

Introduction

Geographic variation in the prevalence of chronic kidney disease and incidence of end-stage renal disease has been previously reported. However, the geographic epidemiology of rapid estimated glomerular filtration rate (eGFR) decline has not been examined.

Methods

We built a longitudinal cohort of 2,107,570 US veterans to characterize the spatial epidemiology of and examine the associations between US county characteristics and rapid eGFR decline.

Results

There were 169,029 (8.02%) with rapid eGFR decline (defined as eGFR slope < –5 ml/min per 1.73 m²/year). The prevalence of rapid eGFR decline adjusted for age, race, gender, diabetes, and hypertension varied by county from 4.10%–6.72% in the lowest prevalence quintile to 8.41%–22.04% in the highest prevalence quintile (P for heterogeneity < 0.001). Examination of adjusted prevalence showed substantial geographic variation in those with and without diabetes and those with and without hypertension (P for heterogeneity < 0.001). Cohort participants had higher odds of rapid eGFR decline when living in counties with unfavorable characteristics in domains including health outcomes (odds ratio [OR] = 1.15; confidence interval [CI] = 1.09–1.22), health behaviors (OR = 1.08; CI = 1.03–1.13), clinical care (OR = 1.11; CI = 1.06–1.16), socioeconomic conditions (OR = 1.15; CI = 1.09–1.22), and physical environment (OR = 1.15; CI = 1.01–1.20); living in counties with high percentage of minorities and immigrants was associated with rapid eGFR decline (OR = 1.25; CI = 1.20–1.31). Spatial analyses suggest the presence of cluster of counties with high prevalence of rapid eGFR decline.

Discussion

Our findings show substantial geographic variation in rapid eGFR decline among US veterans; the variation persists in analyses stratified by diabetes and hypertension status; results show associations between US county characteristics in domains capturing health, socioeconomic, environmental, and diversity conditions, and rapid eGFR decline.

Estimated GFR Decline Following Sodium Phosphate Enemas Versus Polyethylene Glycol for Screening Colonoscopy: A Retrospective Cohort Study

BACKGROUND

Associations between sodium phosphate enemas and nephropathy have raised concerns about the safety of use as part of a bowel-cleansing regimen administered prior to colonoscopies. The objectives of this analysis are to evaluate the impact of sodium phosphate enema versus polyethylene glycol powder for oral solution (PEG) use prior to colonoscopy screening on estimated glomerular filtration rate (eGFR) decline in Veterans Affairs (VA) patients and identify other risk factors contributing to eGFR decline.

STUDY DESIGN

Retrospective cohort study.

SETTING & PARTICIPANTS

70,499 VA patients receiving sodium phosphate enemas (with or without PEG) or PEG alone prior to colonoscopy screenings.

PREDICTOR

Use of either sodium phosphate or PEG.

OUTCOMES

A 50% increase in serum creatinine level over a 15-month, over a 6-week, and between a 9- and 15-month period was used to define any, acute, or long-term eGFR decline, respectively.

MEASUREMENTS

Multivariable logistic regressions estimated the likelihood of eGFR decline conditional on the use of sodium phosphate enemas versus PEG alone, controlling for potential confounders.

RESULTS

A greater proportion of patients using sodium phosphate enemas versus PEG had any (P<0.001) or long-term (P=0.003) eGFR declines, whereas similar proportions had acute eGFR declines (P=0.9). In the adjusted analyses, use of sodium phosphate enemas (± PEG was associated with an increased likelihood of having any (OR, 1.3; 95% CI, 1.2-1.5) or long-term (OR, 1.4; 95% CI, 1.1-1.8) eGFR decline, but not acute eGFR decline (OR, 1.0; 95% CI, 0.6-1.7). Other risk factors for eGFR decline included diabetes and non-iron deficient anemia.

LIMITATIONS

Unobserved heterogeneity due to volume depletion and potential selection bias due to higher-risk patients preferentially prescribed sodium phosphate enemas.

CONCLUSIONS

Use of sodium phosphate enemas versus PEG alone prior to colonoscopy screening increases the risk for VA patients having long-term eGFR decline. Patients with non-iron deficient anemia are at particularly high risk for eGFR decline. These findings motivate the need to re-examine prescribing practices for sodium phosphate enemas as part of a bowel-cleansing regimen.

Abrupt Decline in Kidney Function Before Initiating Hemodialysis and All-Cause Mortality: The Chronic Renal Insufficiency Cohort (CRIC) Study

BACKGROUND

It is not clear whether the pattern of kidney function decline in patients with chronic kidney disease (CKD) may relate to outcomes after reaching end-stage renal disease (ESRD). We hypothesize that an abrupt decline in kidney function prior to ESRD predicts early death after initiating maintenance hemodialysis therapy.

STUDY DESIGN

Prospective cohort study.

SETTING & PARTICIPANTS

The Chronic Renal Insufficiency Cohort (CRIC) Study enrolled men and women with mild to moderate CKD. For this study, we studied 661 individuals who developed chronic kidney failure that required hemodialysis therapy initiation.

PREDICTORS

The primary predictor was the presence of an abrupt decline in kidney function prior to ESRD. We incorporated annual estimated glomerular filtration rates (eGFRs) into a mixed-effects model to estimate patient-specific eGFRs at 3 months prior to initiation of hemodialysis therapy. Abrupt decline was defined as having an extrapolated eGFR≥30mL/min/1.73m(2) at that time point.

OUTCOMES

All-cause mortality within 1 year after initiating hemodialysis therapy.

MEASUREMENTS

Multivariable Cox proportional hazards.

RESULTS

Among 661 patients with CKD initiating hemodialysis therapy, 56 (8.5%) had an abrupt predialysis decline in kidney function and 69 died within 1 year after initiating hemodialysis therapy. After adjustment for demographics, cardiovascular disease, diabetes, and cancer, abrupt decline in kidney function was associated with a 3-fold higher risk for death within the first year of ESRD (adjusted HR, 3.09; 95% CI, 1.65-5.76).

LIMITATIONS

Relatively small number of outcomes; infrequent (yearly) eGFR determinations; lack of more granular clinical data.

CONCLUSIONS

Abrupt decline in kidney function prior to ESRD occurred in a significant minority of incident hemodialysis patients and predicted early death in ESRD.

Clinical and pathological predictors of estimated GFR decline in patients with type 2 diabetes and overt proteinuric diabetic nephropathy

BACKGROUND

The effect of clinical and pathological parameters on the estimated glomerular filtration rate (eGFR) decline has not been investigated in patients with type 2 diabetes and overt proteinuric biopsy-proven diabetic nephropathy.

METHODS

Among 198 patients with type 2 diabetes who underwent renal biopsy and were confirmed to have pure diabetic nephropathy according to the recent classification, 128 patients with overt proteinuria were enrolled. Receiver operating characteristic, net reclassification improvement (NRI) and integrated discrimination improvement (IDI) analyses were performed using models adjusted for various clinical and pathological covariates to determine the best predictors of rapid eGFR decline [defined as >14.9%/year (median eGFR decline)].

RESULTS

A model that incorporated proteinuria showed the largest area under the curve (AUC) among clinical models, which suggested that proteinuria was the best clinical predictor. Although a model incorporating interstitial fibrosis and tubular atrophy (IFTA) score did not display a significantly larger AUC than the model with proteinuria (0.843 vs 0.812, respectively, p = 0.47), a model with both IFTA score and proteinuria had a significantly larger AUC than the model with proteinuria alone (0.875 vs 0.812, respectively, p = 0.014). Similarly, the addition of IFTA score resulted in a significantly greater net reclassification improvement and integrated discrimination improvement than the model with proteinuria alone [NRI: 0.78 (95% CI: 0.43-1.13; p < 0.001), IDI: 0.13 (95% CI: 0.07-0.19; p < 0.001)].

CONCLUSIONS

Our results suggest that not only proteinuria but also tubulointerstitial lesions should be assessed to predict rapid eGFR decline in patients with type 2 diabetes who have overt proteinuria and biopsy-proven diabetic nephropathy.