Novel Risk Factors for Progression of Diabetic and Nondiabetic CKD: Findings From the Chronic Renal Insufficiency Cohort (CRIC) Study.

RATIONALE & OBJECTIVE: Identification of novel risk factors for chronic kidney disease (CKD) progression may inform mechanistic investigations and improve identification of high-risk subgroups. The current study aimed to characterize CKD progression across levels of numerous risk factors and identify independent risk factors for CKD progression among those with and without diabetes. STUDY DESIGN: The Chronic Renal Insufficiency Cohort (CRIC) Study is a prospective cohort study of adults with CKD conducted at 7 US clinical centers. SETTING & PARTICIPANTS: Participants (N=3,379) had up to 12.3 years of follow-up; 47% had diabetes. PREDICTORS: 30 risk factors for CKD progression across sociodemographic, behavioral, clinical, and biochemical domains at baseline. OUTCOMES: Study outcomes were estimated glomerular filtration rate (eGFR) slope and the composite of halving of eGFR or initiation of kidney replacement therapy. ANALYTICAL APPROACH: Stepwise selection of independent risk factors was performed stratified by diabetes status using linear mixed-effects and Cox proportional hazards models. RESULTS: Among those without and with diabetes, respectively, mean eGFR slope was-1.4±3.3 and-2.7±4.7mL/min/1.73m2 per year. Among participants with diabetes, multivariable-adjusted hazard of the composite outcome was approximately 2-fold or greater with higher levels of the inflammatory chemokine CXCL12, the cardiac marker N-terminal pro-B-type natriuretic peptide (NT-proBNP), and the kidney injury marker urinary neutrophil gelatinase-associated lipocalin (NGAL). Among those without diabetes, low serum bicarbonate and higher high-sensitivity troponin T, NT-proBNP, and urinary NGAL levels were all significantly associated with a 1.5-fold or greater rate of the composite outcome. LIMITATIONS: The observational study design precludes causal inference. CONCLUSIONS: Strong associations for cardiac markers, plasma CXCL12, and urinary NGAL are comparable to that of systolic blood pressure≥140mm Hg, a well-established risk factor for CKD progression. This warrants further investigation into the potential mechanisms that these markers indicate and opportunities to use them to improve risk stratification.

Sex-Related Disparities in CKD Progression.

BACKGROUND: In the United States, incidence of ESRD is 1.5 times higher in men than in women, despite men's lower prevalence of CKD. Prior studies, limited by inclusion of small percentages of minorities and other factors, suggested that men have more rapid CKD progression, but this finding has been inconsistent. METHODS: In our prospective investigation of sex differences in CKD progression, we used data from 3939 adults (1778 women and 2161 men) enrolled in the Chronic Renal Insufficiency Cohort Study, a large, diverse CKD cohort. We evaluated associations between sex (women versus men) and outcomes, specifically incident ESRD (defined as undergoing dialysis or a kidney transplant), 50% eGFR decline from baseline, incident CKD stage 5 (eGFR<15 ml/min per 1.73 m2), eGFR slope, and all-cause death. RESULTS: Participants' mean age was 58 years at study entry; 42% were non-Hispanic black, and 13% were Hispanic. During median follow-up of 6.9 years, 844 individuals developed ESRD, and 853 died. In multivariable regression models, compared with men, women had significantly lower risk of ESRD, 50% eGFR decline, progression to CKD stage 5, and death. The mean unadjusted eGFR slope was -1.09 ml/min per 1.73 m2 per year in women and -1.43 ml/min per 1.73 m2 per year in men, but this difference was not significant after multivariable adjustment. CONCLUSIONS: In this CKD cohort, women had lower risk of CKD progression and death compared with men. Additional investigation is needed to identify biologic and psychosocial factors underlying these sex-related differences.

Longitudinal FGF23 Trajectories and Mortality in Patients with CKD.

Elevated fibroblast growth factor 23 (FGF23) levels, measured at a single time, are strongly associated with increased risk of mortality in patients with CKD. There are minimal data on serial FGF23 measurements in CKD. In a prospective case-cohort study of the Chronic Renal Insufficiency Cohort, we measured FGF23 at two to five annual time points (mean 4.0±1.2) in a randomly selected subcohort of 1135 participants, of whom 203 died, and all remaining 390 participants who died through mid-2013. Higher FGF23 was independently associated with increased risk of death in multivariable-adjusted analyses of time-varying FGF23 (hazard ratio per 1-SD increase in ln-transformed FGF23, 1.84; 95% CI, 1.67 to 2.03). Median FGF23 was stable over 5 years of follow-up, but its gradually right-skewed distribution suggested a subpopulation with markedly elevated FGF23. Trajectory analysis revealed three distinct trajectories: stable FGF23 in the majority of participants (slope of lnFGF23 per year =0.03, 95% CI, 0.02 to 0.04, n=724) and smaller subpopulations with slowly (slope=0.14, 95% CI, 0.12 to 0.16, n=486) or rapidly (slope=0.46, 95% CI, 0.38 to 0.54, n=99) rising levels. Compared with stable FGF23, participants with slowly rising FGF23 trajectories were at 4.49-fold higher risk of death (95% CI, 3.17 to 6.35) and individuals with rapidly rising FGF23 trajectories were at 15.23-fold higher risk of death (95% CI, 8.24 to 28.14) in fully adjusted analyses. Trajectory analyses that used four or three annual FGF23 measurements yielded qualitatively similar results. In conclusion, FGF23 levels are stable over time in the majority of patients with CKD, but serial measurements identify subpopulations with rising levels and exceptionally high risk of death.

GDF-15, Galectin 3, Soluble ST2, and Risk of Mortality and Cardiovascular Events in CKD.

RATIONALE & OBJECTIVE: Inflammation, cardiac remodeling, and fibrosis may explain in part the excess risk for cardiovascular disease (CVD) in patients with chronic kidney disease (CKD). Growth differentiation factor 15 (GDF-15), galectin 3 (Gal-3), and soluble ST2 (sST2) are possible biomarkers of these pathways in patients with CKD. STUDY DESIGN: Observational cohort study. SETTING & PARTICIPANTS: Individuals with CKD enrolled in either of 2 multicenter CKD cohort studies: the Seattle Kidney Study or C-PROBE (Clinical Phenotyping and Resource Biobank Study). EXPOSURES: Circulating GDF-15, Gal-3, and sST2 measured at baseline. OUTCOMES: Primary outcome was all-cause mortality. Secondary outcomes included hospitalization for physician-adjudicated heart failure and the atherosclerotic CVD events of myocardial infarction and cerebrovascular accident. ANALYTIC APPROACH: Cox proportional hazards models used to test the association of each biomarker with each outcome, adjusting for demographics, CVD risk factors, and kidney function. RESULTS: Among 883 participants, mean estimated glomerular filtration rate was 49±19mL/min/1.73m2. Higher GDF-15 (adjusted HR [aHR] per 1-SD higher, 1.87; 95% CI, 1.53-2.29), Gal-3 (aHR per 1-SD higher, 1.51; 95% CI, 1.36-1.78), and sST2 (aHR per 1-SD higher, 1.36; 95% CI, 1.17-1.58) concentrations were significantly associated with mortality. Only GDF-15 level was also associated with heart failure events (HR per 1-SD higher, 1.56; 95% CI, 1.12-2.16). There were no detectable associations between GDF-15, Gal-3, or sST2 concentrations and atherosclerotic CVD events. LIMITATIONS: Event rates for heart failure and atherosclerotic CVD were low. CONCLUSIONS: Adults with CKD and higher circulating GDF-15, Gal-3, and sST2 concentrations experienced greater mortality. Elevated GDF-15 concentration was also associated with an increased rate of heart failure. Further work is needed to elucidate the mechanisms linking these circulating biomarkers with CVD in patients with CKD.

Habitual sleep and kidney function in chronic kidney disease: the Chronic Renal Insufficiency Cohort study.

Physiological evidence suggests that sleep modulates kidney function. Our objective was to examine the cross-sectional association between kidney function and objectively-estimated habitual sleep duration, quality and timing in a cohort of patients with mild to moderate chronic kidney disease. This study involved two US clinical centers of the Chronic Renal Insufficiency Cohort (CRIC) study, including 432 participants in a CRIC ancillary sleep study. Habitual sleep duration, quality and timing were measured using wrist actigraphy for 5-7 days. Validated sleep questionnaires assessed subjective sleep quality, daytime sleepiness and risk of sleep apnea. Kidney function was assessed with the estimated glomerular filtration rate using the Chronic Kidney Disease Epidemiology Collaboration equation, and the urinary protein to creatinine ratio. Lower estimated glomerular filtration rate was associated with shorter sleep duration (-1.1 mL min-1  1.73 m-2 per hour less sleep, P = 0.03), greater sleep fragmentation (-2.6 mL min-1  1.73 m-2 per 10% higher fragmentation, P < 0.001) and later timing of sleep (-0.9 mL min-1  1.73 m-2 per hour later, P = 0.05). Higher protein to creatinine ratio was also associated with greater sleep fragmentation (approximately 28% higher per 10% higher fragmentation, P < 0.001). Subjective sleep quality, sleepiness and persistent snoring were not associated with estimated glomerular filtration rate or protein to creatinine ratio. Thus, worse objective sleep quality was associated with lower estimated glomerular filtration rate and higher protein to creatinine ratio. Shorter sleep duration and later sleep timing were also associated with lower estimated glomerular filtration rate. Physicians treating patients with chronic kidney disease should consider inquiring about sleep and possibly sending for clinical sleep assessment. Longitudinal and interventional trials are needed to understand causal direction.

The Association of Sleep Duration and Quality with CKD Progression.

Evidence suggests that sleep disorders are common in individuals with CKD, but the influence of sleep duration and quality on CKD progression is unknown. We examined the association of habitual sleep duration and quality with CKD progression in 431 Chronic Renal Insufficiency Cohort (CRIC) Study participants, of whom 48% were women and 50% had diabetes (mean age of 60 years old, mean eGFR =38 ml/min per 1.73 m2, and median urine protein-to-creatinine ratio [UPCR] =0.20 g/g). We assessed sleep duration and quality by 5-7 days of wrist actigraphy and self-report. Primary outcomes were incident ESRD, eGFR slope, log-transformed UPCR slope, and all-cause death. Participants slept an average of 6.5 hours per night; mean sleep fragmentation was 21%. Over a median follow-up of 5 years, we observed 70 ESRD events and 48 deaths. In adjusted analyses, greater sleep fragmentation associated with increased ESRD risk (hazard ratio, 1.04; 95% confidence interval, 1.01 to 1.07 per 1% increase in fragmentation). In adjusted mixed effects regression models, shorter sleep duration (per hour less) and greater sleep fragmentation (per 1% more) each associated with greater eGFR decline (-1.12 and -0.18 ml/min per 1.73 m2 per year, respectively; P=0.02 and P<0.01, respectively) and greater log UPCR slope (0.06/yr and 0.01/yr, respectively; P=0.02 and P<0.001, respectively). Self-reported daytime sleepiness associated with increased risk for all-cause death (hazard ratio, 1.11; 95% confidence interval, 1.02 to 1.20 per one-point increase in the Epworth Sleepiness Scale score). These findings suggest that short and poor-quality sleep are unrecognized risk factors for CKD progression.

Growth Differentiation Factor-15 and Risk of CKD Progression.

Growth differentiation factor-15 (GDF-15) is a member of the TGF-ß cytokine superfamily that is widely expressed and may be induced in response to tissue injury. Elevations in GDF-15 may identify a novel pathway involved in loss of kidney function among patients with CKD. Among participants in the Clinical Phenotyping and Resource Biobank (C-PROBE) study and the Seattle Kidney Study (SKS), we tested whether kidney tissue expression of GDF15 mRNA correlates with circulating levels of GDF-15 and whether elevations in circulating GDF-15 are associated with decline in kidney function. In matching samples of 24 patients with CKD from the C-PROBE study, circulating GDF-15 levels significantly correlated with intrarenal GDF15 transcript levels (r=0.54, P=0.01). Among the 224 C-PROBE and 297 SKS participants, 72 (32.1%) and 94 (32.0%) patients, respectively, reached a composite end point of 30% decline in eGFR or progression to ESRD over a median of 1.8 and 2.0 years of follow up, respectively. In multivariable models, after adjusting for potential confounders, every doubling of GDF-15 level associated with a 72% higher (95% confidence interval, 1.21 to 4.45; P=0.003) and 65% higher (95% confidence interval, 1.08 to 2.50; P=0.02) risk of progression of kidney disease in C-PROBE and SKS participants, respectively. These results show that circulating GDF-15 levels strongly correlated with intrarenal expression of GDF15 and significantly associated with increased risk of CKD progression in two independent cohorts. Circulating GDF-15 may be a marker for intrarenal GDF15-related signaling pathways associated with CKD and CKD progression.

Evaluating safety of thrombolysis in chronic kidney disease patients presenting with pulmonary embolism using propensity score matching.

To assess the safety of thrombolytic therapy in chronic kidney disease (CKD) patients who present with pulmonary embolism (PE). We used the Nationwide Inpatient Sample Database to identify patients who underwent thrombolysis for PE between 2010 and 2014. The patients were divided into two groups: (1) No CKD and (2) CKD. Patients with and without CKD were matched using 1:1 propensity score matching and a caliper width of 0.01. The primary outcomes were in-hospital mortality and hemorrhagic events. The secondary outcomes were blood transfusions, length of stay and total hospitalization charge. Two separate, multivariate analyses were also performed to determine the predictors for primary outcomes. The No CKD group had 16,238 and CKD group had 1341 patients prior to matching. Patients with CKD were older (Median age 67 vs. 57 years; p < 0.01), male (60.6 vs. 51.8%) and had a higher prevalence of coronary artery disease, congestive heart failure, diabetes, hyperlipidemia, hypertension, and prior stroke among other comorbidities. They also had significantly higher rate of in-hospital mortality (OR 1.66) and hemorrhagic events (OR 1.47) prior to matching. Post-matching, there was no difference in hospital mortality (22.9 vs. 21.8%; p = 0.51) or hemorrhagic events (3.8 vs. 3.0%; p = 0.27) between CKD and No CKD groups. Patients with CKD had a longer length of stay, but no difference in proportion of patients receiving a blood transfusion and total hospitalization charges post-matching. Multivariate analysis showed that CKD did not predict mortality (OR 0.88, 0.75-1.02; p = 0.09) or hemorrhagic events (OR 0.89, 95% CI 0.76-1.04; 0.13). There was no increase in rate of hospital mortality or hemorrhagic events among CKD patients who underwent thrombolysis for PE.

Prevalence, Predictors, and Outcomes of Pulmonary Hypertension in CKD.

Pulmonary hypertension (PH) is associated with poor outcomes in the dialysis and general populations, but its effect in CKD is unclear. We evaluated the prevalence and predictors of PH measures and their associations with long-term clinical outcomes in patients with nondialysis-dependent CKD. Chronic Renal Insufficiency Cohort (CRIC) Study participants who had Doppler echocardiography performed were considered for inclusion. PH was defined as the presence of estimated pulmonary artery systolic pressure (PASP) >35 mmHg and/or tricuspid regurgitant velocity (TRV) >2.5 m/s. Associations between PH, PASP, and TRV and cardiovascular events, renal events, and all-cause mortality were examined using Cox proportional hazards models. Of 2959 eligible participants, 21% (n=625) had PH, with higher rates among those with lower levels of kidney function. In the multivariate model, older age, anemia, lower left ventricular ejection fraction, and presence of left ventricular hypertrophy were associated with greater odds of having PH. After adjusting for relevant confounding variables, PH was independently associated with higher risk for death (hazard ratio, 1.38; 95% confidence interval, 1.10 to 1.72) and cardiovascular events (hazard ratio, 1.23; 95% confidence interval, 1.00 to 1.52) but not renal events. Similarly, TRV and PASP were associated with death and cardiovascular events but not renal events. In this study of patients with CKD and preserved left ventricular systolic function, we report a high prevalence of PH. PH and higher TRV and PASP (echocardiographic measures of PH) are associated with adverse outcomes in CKD. Future studies may explain the mechanisms that underlie these findings.

Race/Ethnicity and Cardiovascular Outcomes in Adults With CKD: Findings From the CRIC (Chronic Renal Insufficiency Cohort) and Hispanic CRIC Studies.

BACKGROUND: Non-Hispanic blacks and Hispanics with end-stage renal disease have a lower risk for death than non-Hispanic whites, but data for racial/ethnic variation in cardiovascular outcomes for non-dialysis-dependent chronic kidney disease are limited. STUDY DESIGN: Prospective cohort. SETTING & PARTICIPANTS: 3,785 adults with entry estimated glomerular filtration rates of 20 to 70mL/min/1.73m(2) enrolled in the CRIC (Chronic Renal Insufficiency Cohort) Study. PREDICTORS: Race/ethnicity (non-Hispanic white, non-Hispanic black, and Hispanic). OUTCOMES: Cardiovascular outcomes (atherosclerotic events [myocardial infarction, stroke, or peripheral arterial disease] and heart failure) and a composite of each cardiovascular outcome or all-cause death. MEASUREMENTS: Multivariable Cox proportional hazards. RESULTS: During a median follow-up of 6.6 years, we observed 506 atherosclerotic events, 551 heart failure events, and 692 deaths. In regression analyses, there were no significant differences in atherosclerotic events among the 3 racial/ethnic groups. In analyses stratified by clinical site, non-Hispanic blacks had a higher risk for heart failure events (HR, 1.59; 95% CI, 1.29-1.95), which became nonsignificant after adjustment for demographic factors and baseline kidney function. In contrast, Hispanics had similar risk for heart failure events as non-Hispanic whites. In analyses stratified by clinical site, compared with non-Hispanic whites, non-Hispanic blacks were at similar risk for atherosclerotic events or death. However, after further adjustment for cardiovascular risk factors, medications, and mineral metabolism markers, non-Hispanic blacks had 17% lower risk for the outcome (HR, 0.83; 95% CI, 0.69-0.99) than non-Hispanic whites, whereas there was no significant association with Hispanic ethnicity. LIMITATIONS: Hispanics were largely recruited from a single center, and the study was underpowered to evaluate the association between Hispanic ethnicity and mortality. CONCLUSIONS: There were no significant racial/ethnic differences in adjusted risk for atherosclerotic or heart failure outcomes. Future research is needed to better explain the reduced risk for atherosclerotic events or death in non-Hispanic blacks compared with non-Hispanic whites.

Time-updated systolic blood pressure and the progression of chronic kidney disease: a cohort study.

BACKGROUND: Previous reports of the longitudinal association between achieved blood pressure (BP) and end-stage renal disease (ESRD) among patients with chronic kidney disease (CKD) have not incorporated time-updated BP with appropriate covariate adjustment. OBJECTIVE: To assess the association between baseline and time-updated systolic blood pressure (SBP) with CKD progression. DESIGN: Observational, prospective cohort study. (ClinicalTrials.gov: NCT00304148). SETTING: 7 U.S. clinical centers. PATIENTS: Patients in the Chronic Renal Insufficiency Cohort Study (n = 3708) followed for a median of 5.7 years (25th to 75th percentile, 4.6 to 6.7 years). MEASUREMENTS: The mean of 3 seated SBP measurements made up the visit-specific SBP. Time-updated SBP was the mean of that and all previous visits. Outcomes were ESRD and the composite end point of ESRD or halving of the estimated glomerular filtration rate. Analyses investigating baseline and time-updated SBP used Cox proportional hazards models and marginal structural models, respectively. RESULTS: Systolic blood pressure was 130 mm Hg or greater at all visits in 19.2% of patients. The hazard ratio for ESRD among patients with SBP of 130 to 139 mm Hg, compared with SBP less than 120 mm Hg, was 1.46 (95% CI, 1.13 to 1.88) using only baseline data and 2.37 (CI, 1.48 to 3.80) using time-updated data. Among patients with SBP of 140 mm Hg or greater, corresponding hazard ratios were 1.46 (CI, 1.18 to 1.88) and 3.37 (CI, 2.26 to 5.03) for models using only baseline data and those using time-updated data, respectively. LIMITATION: Blood pressure was measured once annually, and the cohort was not a random sample. CONCLUSION: Time-updated SBP greater than 130 mm Hg was more strongly associated with CKD progression than analyses based on baseline SBP. PRIMARY FUNDING SOURCE: National Institute of Diabetes and Digestive and Kidney Diseases.

Sodium Excretion and the Risk of Cardiovascular Disease in Patients With Chronic Kidney Disease.

IMPORTANCE: Patients with chronic kidney disease (CKD) are at an increased risk of cardiovascular disease (CVD) compared with the general population. Prior studies have produced contradictory results on the association of dietary sodium intake with risk of CVD, and this relationship has not been investigated in patients with CKD. OBJECTIVE: To evaluate the association between urinary sodium excretion and clinical CVD events among patients with CKD. DESIGN, SETTING, AND PARTICIPANTS: A prospective cohort study of patients with CKD from 7 locations in the United States enrolled in the Chronic Renal Insufficiency Cohort Study and followed up from May 2003 to March 2013. EXPOSURES: The cumulative mean of urinary sodium excretion from three 24-hour urinary measurements and calibrated to sex-specific mean 24-hour urinary creatinine excretion. MAIN OUTCOMES AND MEASURES: A composite of CVD events defined as congestive heart failure, stroke, or myocardial infarction. Events were reported every 6 months and confirmed by medical record adjudication. RESULTS: Among 3757 participants (mean age, 58 years; 45% women), 804 composite CVD events (575 heart failure, 305 myocardial infarction, and 148 stroke) occurred during a median 6.8 years of follow-up. From lowest (<2894 mg/24 hours) to highest (≥4548 mg/24 hours) quartile of calibrated sodium excretion, 174, 159, 198, and 273 composite CVD events occurred, and the cumulative incidence was 18.4%, 16.5%, 20.6%, and 29.8% at median follow-up. In addition, the cumulative incidence of CVD events in the highest quartile of calibrated sodium excretion compared with the lowest was 23.2% vs 13.3% for heart failure, 10.9% vs 7.8% for myocardial infarction, and 6.4% vs 2.7% for stroke at median follow-up. Hazard ratios of the highest quartile compared with the lowest quartile were 1.36 (95% CI, 1.09-1.70; P = .007) for composite CVD events, 1.34 (95% CI, 1.03-1.74; P = .03) for heart failure, and 1.81 (95% CI, 1.08-3.02; P = .02) for stroke after multivariable adjustment. Restricted cubic spline analyses of the association between sodium excretion and composite CVD provided no evidence of a nonlinear association (P = .11) and indicated a significant linear association (P < .001). CONCLUSIONS AND RELEVANCE: Among patients with CKD, higher urinary sodium excretion was associated with increased risk of CVD.

Urine neutrophil gelatinase-associated lipocalin and risk of cardiovascular disease and death in CKD: results from the Chronic Renal Insufficiency Cohort (CRIC) Study.

BACKGROUND: Chronic kidney disease is common and is associated with increased cardiovascular disease risk. Currently, markers of renal tubular injury are not used routinely to describe kidney health and little is known about the risk of cardiovascular events and death associated with these biomarkers independent of glomerular filtration-based markers (such as serum creatinine or albuminuria). STUDY DESIGN: Cohort study, CRIC (Chronic Renal Insufficiency Cohort) Study. SETTING & PARTICIPANTS: 3,386 participants with estimated glomerular filtration rate of 20 to 70mL/min/1.73m(2) enrolled from June 2003 through August 2008. PREDICTOR: Urine neutrophil gelatinase-associated lipocalin (NGAL) concentration. OUTCOMES: Adjudicated heart failure event, ischemic atherosclerotic event (myocardial infarction, ischemic stroke, or peripheral artery disease), and death through March 2011. MEASUREMENTS: Urine NGAL measured at baseline with a 2-step assay using chemiluminescent microparticle immunoassay technology on an ARCHITECT i2000SR (Abbott Laboratories). RESULTS: There were 428 heart failure events (during 16,383 person-years of follow-up), 361 ischemic atherosclerotic events (during 16,584 person-years of follow-up), and 522 deaths (during 18,214 person-years of follow-up). In Cox regression models adjusted for estimated glomerular filtration rate, albuminuria, demographics, traditional cardiovascular disease risk factors, and cardiac medications, higher urine NGAL levels remained associated independently with ischemic atherosclerotic events (adjusted HR for the highest [>49.5ng/mL] vs lowest [≤6.9ng/mL] quintile, 1.83 [95% CI, 1.20-2.81]; HR per 0.1-unit increase in log urine NGAL, 1.012 [95% CI, 1.001-1.023]), but not heart failure events or deaths. LIMITATIONS: Urine NGAL was measured only once. CONCLUSIONS: Among patients with chronic kidney disease, urine levels of NGAL, a marker of renal tubular injury, were associated independently with future ischemic atherosclerotic events, but not with heart failure events or deaths.

Association between chronic kidney disease progression and cardiovascular disease: results from the CRIC Study.

BACKGROUND AND AIMS: There is limited information on the risk of progression of chronic kidney disease (CKD) among individuals with CVD (cardiovascular disease). We studied the association between prevalent CVD and the risk of progression of CKD among persons enrolled in a long-term observational study. METHODS: A prospective cohort study of 3,939 women and men with CKD enrolled in the chronic renal insufficiency cohort (CRIC) study between June 2003 and June 2008. Prevalent cardiovascular disease (myocardial infarction/revascularization, heart failure, stroke, and peripheral vascular disease) was determined by self-report at baseline. The primary outcome was a composite of either end-stage renal disease or a 50% decline in estimated glomerular filtration rate (eGFR) from baseline. RESULTS: One-third (1,316 of 3,939, 33.4%) of the study participants reported a history of any cardiovascular disease, and 9.6% (n = 382) a history of heart failure at baseline. After a median follow up of 6.63 years, 1,028 patients experienced the primary outcome. The composite of any CVD at baseline was not independently associated with the primary outcome (Hazard Ratio 1.04 95% CI (0.91, 1.19)). However, a history of heart failure was independently associated with a 29% higher risk of the primary outcome (Hazard Ratio 1.29 95% CI (1.06, 1.57)). The relationship between heart failure and risk of CKD progression was consistent in subgroups defined by age, race, gender, baseline eGFR, and diabetes. Neither the composite measure of any CVD or heart failure was associated with the rate of decline in eGFR. CONCLUSIONS: Self-reported heart failure was an independent risk factor for the development of the endpoint of ESRD or 50% decline in GFR in a cohort of patients with chronic kidney disease.

Limited health literacy is associated with low glomerular filtration in the Chronic Renal Insufficiency Cohort (CRIC) study.

BACKGROUND: Low health literacy in the general population is associated with increased risk of death and hospitalization. The evaluation of health literacy in individuals with predialysis chronic kidney disease (CKD) is limited. METHODS: We conducted a cross-sectional study to evaluate the associations of limited health literacy with kidney function and cardiovascular disease (CVD) risk factors in 2,340 non-Hispanic (NH) Whites and Blacks aged 21 - 74 years with mild-to-moderate CKD. Limited health literacy was defined as a Short Test of Functional Health Literacy in Adults (STOFHLA) score ≤ 22. Outcomes evaluated included estimated glomerular filtration rate (eGFR), 24-hour urine protein excretion, and CVD risk factors. RESULTS: The prevalence of limited health literacy was 28% in NH-Blacks and 5% in NH-Whites. Compared with participants with adequate health literacy, those with limited health literacy were more likely to have lower eGFR (34 vs. 42 mL/min/1.73 m2); higher urine protein/24-hours (0.31 vs. 0.15 g); and higher self-reported CVD (61 vs. 37%); and were less likely to have BP < 130/80 mmHg (51 vs. 58%); p ≤ 0.01 for each comparison. After adjustment, limited health literacy was associated with self-reported CVD (OR 1.51, 95% CI 1.13 - 2.03) and lower eGFR (ß -2.47, p = 0.03). CONCLUSION: In this CKD cohort, limited health literacy was highly prevalent, especially among NH-Blacks, and it was associated with lower eGFR and a less favorable CVD risk factor profile. Further studies are needed to better understand these associations and inform the development of health literacy interventions among individuals with CKD.

Increasing use of vitamin D supplementation in the chronic renal insufficiency cohort study.

OBJECTIVE: This study examined rates and determinants of vitamin D supplementation among Chronic Renal Insufficiency Cohort (CRIC) participants and determined the association between dose and 25-hydroxyvitamin D (25(OH)D) level. The 2010 Institute of Medicine Report noted a significant increase in vitamin D supplementation in the general population, but use in chronic kidney disease (CKD) is unknown. METHODS: CRIC is a multicenter prospective observational cohort study of 3,939 participants with a median baseline age of 60 and an estimated glomerular filtration rate (eGFR) of 42.1 mL/minute per 1.73 m2. Of the cohort, 54.9% was male, 42.1% were Black, and 48.4% were diabetic. Multivariable logistic generalized estimating equations were used to examine determinants of supplementation use assessed annually between 2003 and 2011. Cross-sectional linear regression models, based on a subset of 1,155 participants, assessed associations between supplement dose and 25(OH)D level, measured by high-performance liquid chromatography coupled with tandem mass spectrometry. RESULTS: The proportion of participants reporting supplement use increased (P < .0001), from 10% at baseline to 44% at 7-year follow-up visits. This was largely due to initiation of products containing only ergocalciferol or cholecalciferol. The odds of supplementation were greater in older, female, non-Black, married participants with greater education and lower body mass index. Among participants taking supplementation, dose was positively associated with 25(OH)D level, adjusted for race, season, diabetes, dietary intake, eGFR, and proteinuria. Only 3.8% of non-Black and 16.5% of Black participants taking a supplement were deficient (<20 ng/mL), whereas 22.7% of non-Black and 62.4% of black participants not reporting supplement use were deficient. CONCLUSIONS: Vitamin D supplementation rates rose significantly among CRIC participants over 7 years of follow-up and were associated with greater serum 25(OH)D levels. Studies of vitamin D levels on clinical outcomes in CKD and future vitamin D interventional studies should consider these changes in supplementation practices.

Impact of Antihypertensive Medication Changes After Renal Denervation Among Different Patient Groups: SPYRAL HTN-ON MED.

BACKGROUND: The SPYRAL HTN-ON MED (Global Clinical Study of Renal Denervation With the Symplicity Spyral Multi-electrode Renal Denervation System in Patients With Uncontrolled Hypertension in the Absence of Antihypertensive Medications)trial showed significant office and nighttime systolic blood pressure (BP) reductions in patients with hypertension following renal denervation (RDN) compared with sham-control patients, despite similar 24-hour BP reductions. We compared antihypertensive medication and BP changes among prespecified subpopulations. METHODS: The multicenter, randomized, sham-controlled, blinded SPYRAL HTN-ON MED trial (n=337) evaluated BP changes after RDN compared with a sham procedure in patients with hypertension prescribed 1 to 3 antihypertensive drugs. Most patients (n=187; 54%) were enrolled outside the United States, while 156 (46%) US patients were enrolled, including 60 (18%) Black Americans. RESULTS: Changes in detected antihypertensive drugs were similar between RDN and sham group patients in the outside US cohort, while drug increases were significantly more common in the US sham group compared with the RDN group. Patients from outside the United States showed significant reductions in office and 24-hour mean systolic BP at 6 months compared with the sham group, whereas BP changes were similar between RDN and sham in the US cohort. Within the US patient cohort, Black Americans in the sham control group had significant increases in medication burden from baseline through 6 months (P=0.003) but not in the RDN group (P=0.44). CONCLUSIONS: Patients enrolled outside the United States had minimal antihypertensive medication changes between treatment groups and had significant office and 24-hour BP reductions compared with the sham group. Increased antihypertensive drug burden in the US sham cohort, especially among Black Americans, may have diluted the treatment effect in the combined trial population. REGISTRATION: URL: https://www.clinicaltrials.gov; Unique identifier: NCT02439775.

Association of serum bicarbonate with risk of renal and cardiovascular outcomes in CKD: a report from the Chronic Renal Insufficiency Cohort (CRIC) study.

BACKGROUND: The purpose of this study is to evaluate serum bicarbonate level as a risk factor for renal outcomes, cardiovascular events, and mortality in patients with chronic kidney disease (CKD). STUDY DESIGN: Observational cohort study. SETTING & PARTICIPANTS: 3,939 participants with CKD stages 2-4 who enrolled in the Chronic Renal Insufficiency Cohort (CRIC) between June 2003 and December 2008. PREDICTOR: Serum bicarbonate level. OUTCOMES: Renal outcomes, defined as end-stage renal disease (either initiation of dialysis therapy or kidney transplantation) or 50% reduction in estimated glomerular filtration rate (eGFR); atherosclerotic events (myocardial infarction, stroke, or peripheral arterial disease); congestive heart failure events; and death. MEASUREMENTS: Time to event. RESULTS: Mean eGFR was 44.8 ± 16.8 (SD) mL/min/1.73 m(2), and median serum bicarbonate level was 24 (IQR, 22-26) mEq/L. During a median follow-up of 3.9 years, 374 participants died, 767 had a renal outcome, 332 experienced an atherosclerotic event, and 391 had a congestive heart failure event. In adjusted analyses, the risk of developing a renal end point was 3% lower per 1-mEq/L increase in serum bicarbonate level (HR, 0.97; 95% CI, 0.94-0.99; P = 0.01). The association was stronger for participants with eGFR >45 mL/min/1.73 m(2) (HR, 0.91; 95% CI, 0.85-0.97; P = 0.004). The risk of heart failure increased by 14% (HR, 1.14; 95% CI, 1.03-1.26; P = 0.02) per 1-mEq/L increase in serum bicarbonate level over 24 mEq/L. Serum bicarbonate level was not associated independently with atherosclerotic events (HR, 0.99; 95% CI, 0.95-1.03; P = 0.6) and all-cause mortality (HR, 0.98; 95% CI, 0.95-1.02; P = 0.3). LIMITATIONS: Single measurement of sodium bicarbonate. CONCLUSIONS: In a cohort of participants with CKD, low serum bicarbonate level was an independent risk factor for kidney disease progression, particularly for participants with preserved kidney function. The risk of heart failure was higher at the upper extreme of serum bicarbonate levels. There was no association between serum bicarbonate level and all-cause mortality or atherosclerotic events.

Primary hyperaldosteronism decoded: a case of curable resistant hypertension.

Patients with resistant hypertension have a higher incidence of secondary causes of hypertension compared with the general hypertensive population. It is important to screen such patients for secondary causes of hypertension because appropriate treatment can lead to improved blood pressure control or even cure these patients, and thus avoid the cardiovascular morbidity and mortality associated with uncontrolled hypertension. One common cause of secondary hypertension, often associated with hypokalemia, is primary hyperaldosteronism or Conn syndrome. Aldosterone is a mineralocorticoid hormone produced in the outer layer of the adrenal cortex (the zona glomerulosa); its primary action is to increase sodium and water reabsorption by the kidney. Once the diagnosis of primary aldosteronism is made, it is necessary to determine if aldosterone production is unilateral or bilateral. When production is unilateral (most often from a functional adenoma), surgery is potentially curative. The authors report a case and review the diagnostic workup of Conn syndrome in which resistant hypertension and hypokalemia were cured by unilateral adrenalectomy.

Urinary sodium is a potent correlate of proteinuria: lessons from the chronic renal insufficiency cohort study.

BACKGROUND: While higher blood pressure is known to increase proteinuria, whether increased dietary sodium as estimated from 24-hour urinary excretion correlates with increased proteinuria in patients with chronic kidney disease (CKD) is not well studied. METHODS: We measured 24-hour urinary sodium, potassium and protein excretion in 3,680 participants in the Chronic Renal Insufficiency Cohort study, to determine the relationship between urinary sodium and potassium and urinary protein excretion in patients with CKD. We stratified our data based on the presence or absence of diabetes given the absence of any data on this relationship and evidence that diabetics had greater urinary protein excretion at nearly every level of urinary sodium excretion. Multiple linear regressions were used with a stepwise inclusion of covariates such as systolic blood pressure, demographics, hemoglobin A1c and type of antihypertensive medications to evaluate the relationship between urinary electrolyte excretion and proteinuria. RESULTS: Our data demonstrated that urinary sodium (+1 SD above the mean), as a univariate variable, explained 12% of the variation in proteinuria (ß = 0.29, p < 0.0001), with rising urinary sodium excretion associated with increasing proteinuria. The significance of that relationship was only partially attenuated with adjustment for demographic and clinical factors and the addition of 24-hour urinary potassium to the model (ß = 0.13, R(2) = 0.35, p < 0.0001). CONCLUSIONS: An understanding of the relationship between these clinical factors and dietary sodium may allow a more tailored approach for dietary salt restriction in patients with CKD.