Background The purpose of this study is to evaluate serum bicarbonate 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 3939 participants with CKD stages 2-4 who enrolled in the Chronic Renal Insufficiency Cohort (CRIC) between June 2003 - December 2008. Predictor Serum bicarbonate. Outcomes Renal outcomes, defined as end-stage renal disease (either initiation of dialysis or kidney transplantation) or 50% reduction in eGFR; atherosclerotic events (myocardial infarction, stroke, peripheral arterial disease); congestive heart failure events; and death. Measurements Time to event. Results The mean eGFR was 44.8 ± 16.8 (SD) mL/min/1.73 m2, and the median serum bicarbonate was 24 (IQR, 22-26) mEq/L. During a median follow-up of 3.9 years, 374 participants died, 767 had a renal outcome, and 332 experienced an atherosclerotic event and 391 had a congestive heart failure event. In adjusted analyses, the risk of developing a renal endpoint was 3% lower per mEq/L increase in serum bicarbonate (HR, 0.97; 95% CI, 0.94-0.99; p=0.01). The association was stronger for participants with eGFR> 45ml/min/1.73m2 (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 mEq/L increase in serum bicarbonate over 24 mEq/L. Serum bicarbonate was not independently associated 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 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. There was no association between serum bicarbonate and all-cause mortality or atherosclerotic events.

Background and objectives Low health-related quality of life is associated with increased mortality in patients with ESRD. However, little is known about demographic and clinical factors associated with health-related quality of life or its effect on outcomes in adults with CKD.Design, settings, participants, & measurements Data from 3837 adult participants with mild to severe CKD enrolled in the prospective observational Chronic Renal Insufficiency Cohort and Hispanic Chronic Renal Insufficiency Cohort Studies were analyzed. Health-related quality of life was assessed at baseline with the Kidney Disease Quality of Life-36 and its five subscales: mental component summary, physical component summary, burden of kidney disease (burden), effects of kidney disease (effects), and symptoms and problems of kidney disease (symptoms). Low health-related quality of life was defined as baseline score .1 SD below the mean. Using Cox proportional hazards analysis, the relationships between low health-related quality of life and the following outcomes were examined: (1) CKD progression (50% eGFR loss or incident ESRD), (2) incident cardiovascular events, and (3) all-cause death.Results Younger age, women, low education, diabetes, vascular disease, congestive heart failure, obesity, and lower eGFR were associated with low baseline health-related quality of life (P,0.05). During a median follow-up of 6.2 years, there were 1055 CKD progression events, 841 cardiovascular events, and 694 deaths. Significantly higher crude rates of CKD progression, incident cardiovascular events, and all-cause death were observed among participants with low health-related quality of life in all subscales (P,0.05). In fully adjusted models, low physical component summary, effects, and symptoms subscales were independently associated with a higher risk of incident cardiovascular events and death, whereas low mental component summary was independently associated with a higher risk of death (P,0.05). Low health-related quality of life was not associated with CKD progression.Conclusions Low health-related quality of life across several subscales was independently associated with a higher risk of incident cardiovascular events and death but not associated with CKD progression.

Studies of hemodialysis patients have shown a U-shaped association between systolic blood pressure (SBP) and mortality. These studies have largely relied on dialysis-unit SBP measures and have not evaluated whether this U-shape also exists in advanced chronic kidney disease (CKD), prior to starting hemodialysis. We determined the association between SBP and mortality at advanced CKD and again after initiation of hemodialysis. This was a prospective study of Chronic Renal Insufficiency Cohort (CRIC) participants with advanced CKD followed through initiation of hemodialysis. We studied the association between SBP and mortality when participants: 1) had an estimated glomerular filtration rate <30 ml/min/1.73m2 (N=1,705); 2) initiated hemodialysis and had dialysis-unit SBP measures (N=403) and; 3) initiated hemodialysis and had out-of-dialysis-unit SBP measured at a CRIC study visit (N=326). Cox models adjusted for demographics, cardiovascular risk factors and dialysis parameters. A quadratic term for SBP was included to test for a U-shaped association. At advanced CKD, there was no association between SBP and mortality (HR 1.02 [95% CI: 0.98–1.07] per every 10 mm Hg increase). Among participants who started hemodialysis, a U-shaped association between dialysis-unit SBP and mortality was observed. In contrast, there was a linear association between out-of-dialysis-unit SBP and mortality (HR 1.26 [95% CI: 1.14–1.40] per every 10 mm Hg increase). In conclusion, more efforts should be made to obtain out-of-dialysis-unit SBP which may merit more consideration as a target for clinical management and in interventional trials.

Background Little is known regarding chronic kidney disease (CKD) in Hispanics. We compared baseline characteristics of Hispanic participants in the Chronic Renal Insufficiency Cohort (CRIC) and Hispanic-CRIC (H-CRIC) Studies with non-Hispanic CRIC participants. Study Design Cross-sectional analysis Setting and Participants Participants were aged 21–74 years with CKD using age-based glomerular filtration rate (eGFR) at enrollment into the CRIC/H-CRIC Studies. H-CRIC included Hispanics recruited at the University of Illinois from 2005–2008 while CRIC included Hispanics and non-Hispanics recruited at seven clinical centers from 2003–2007. Factor Race/ethnicity Outcomes Blood pressure, angiotensin-converting enzyme (ACE) inhibitor/angiotensin receptor blocker (ARB) use, CKD-associated complications Measurements Demographic characteristics, laboratory data, blood pressure, and medications were assessed using standard techniques and protocols Results Among H-CRIC/ CRIC participants, 497 were Hispanic, 1650 non-Hispanic Black, and 1638 non-Hispanic White. Low income and educational attainment were nearly twice as prevalent in Hispanics compared with non-Hispanics (p<0.01). Hispanics had self-reported diabetes (67%) more frequently than non-Hispanic Blacks (51%) and Whites (40%) (p<0.01). Blood pressure > 130/80 mmHg was more common in Hispanics (62%) compared with Blacks (57%) and Whites (35%) (p<0.05), and abnormalities in hematologic, metabolic, and bone metabolism parameters were more prevalent in Hispanics (p<0.05), even after stratifying by entry eGFR. Hispanics had the lowest receipt of ACE inhibitor/ARB among high-risk subgroups, including participants with diabetes, proteinuria, and blood pressure > 130/80 mmHg. Mean eGFR (ml/min/m2) was lower in Hispanics (39.6) than in Blacks (43.7) and Whites (46.2), while median proteinuria was higher in Hispanics (0.72 g/d) than in Blacks (0.24 g/d) and Whites (0.12 g/d) (p<0.01). Limitations Generalizability; observed associations limited by residual bias and confounding Conclusions Hispanics with CKD in CRIC/H-CRIC Studies are disproportionately burdened with lower socioeconomic status, more frequent diabetes mellitus, less ACE inhibitor/ARB use, worse blood pressure control, and more severe CKD and associated complications than their non-Hispanic counterparts.

Hispanics are the largest racial/ethnic minority group in the United States, and they experience a substantial burden of kidney disease. Although the prevalence of chronic kidney disease (CKD) is similar or slightly lower in Hispanics than non-Hispanic whites, the age- and sex-adjusted prevalence rate of end-stage renal disease is almost 50% higher in Hispanics compared with non-Hispanic whites. This has been attributed in part to faster CKD progression among Hispanics. Furthermore, Hispanic ethnicity has been associated with a greater prevalence of cardiovascular disease risk factors, including obesity and diabetes, as well as CKD-related complications. Despite their less favorable socioeconomic status, which often leads to limited access to quality health care, and their high comorbid condition burden, the risk for mortality among Hispanics appears to be lower than for non-Hispanic whites. This survival paradox has been attributed to a complex interplay between sociocultural and psychosocial factors, as well as other factors. Future research should focus on evaluating the long-term impact of these factors on patient-centered and clinical outcomes. National policies are needed to improve access to and quality of health care among Hispanics with CKD.