Chronic kidney disease (CKD) is a national public health problem. Although the prevalence of early stages of CKD is similar across different racial/ethnic and socioeconomic groups, the prevalence of ...end-stage renal disease is greater for minorities than their non-Hispanic white peers. Paradoxically, once on dialysis, minorities experience survival rates that exceed their non-Hispanic white peers. Advancing our understanding of the unique interplay of biological, genetic, environmental, sociocultural, and health care system level factors may prompt reorientation of our approach to health promotion and disease prevention. The potential of this new approach is to create previously unimagined gains to improve patient outcomes and reduce health inequities for patients with CKD.
Background The prevalence of chronic kidney disease (CKD) is increasing in the United States, caused in part by older age and increasing prevalences of hypertension and type 2 diabetes. CKD is silent ...and undetected until advanced stages. The study of populations with earlier stages of kidney disease may improve outcomes of CKD. Methods The Kidney Early Evaluation Program (KEEP), a National Kidney Foundation program, is a targeted community-based health-screening program enrolling individuals 18 years and older with diabetes, hypertension, or family history of kidney disease, diabetes, or hypertension. Participants who had received transplants or were on regular dialysis treatment were excluded from this analysis. The National Health and Nutrition Examination Survey (NHANES) 1999-2004 was a nationally representative cross-sectional survey; participants were interviewed in their homes and/or received standardized medical examinations in mobile examination centers. Results Of the 61,675 KEEP participants, 16,689 (27.1%) were found to have CKD. In the NHANES sample of 14,632 participants, 2,734 (15.3%) had CKD. Older age, smoking, obesity, diabetes, hypertension, and cardiovascular disease were associated significantly with CKD in both KEEP and NHANES ( P < 0.05 for all). Of note, the likelihood for CKD in African Americans differed between KEEP (odds ratio, 0.81; P < 0.001) and NHANES (odds ratio, 1.10; P = 0.2). Conclusion A greater prevalence of CKD was detected in the KEEP screening than in the NHANES data. KEEP has the limitations common to population-screening studies and conclusions for population-attributable risk may be limited. The targeted nature of the KEEP screening program and the large sample size with clinical characteristics comparable to NHANES validates KEEP as a valuable cohort to explore health associations for the CKD and at-risk-for-CKD populations in the United States.
Background The National Kidney Foundation has recommended that the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equation replace the Modification of Diet in Renal Disease (MDRD) Study ...equation. Before implementing this change in the Kidney Early Evaluation Program (KEEP), we compared characteristics of reclassified individuals and mortality risk predictions using the new equation. Methods Of 123,704 eligible KEEP participants, 116,321 with data available for this analysis were included. Glomerular filtration rate (GFR) was estimated using the MDRD Study (eGFRMDRD ) and CKD-EPI (eGFRCKD-EPI ) equations with creatinine level calibrated to standardized methods. Participants were characterized by eGFR category: >120, 90-119, 60-89, 45-59, 30-44, and <30 mL/min/1.73 m2 . Clinical characteristics ascertained included age, race, sex, diabetes, hypertension, coronary artery disease, congestive heart failure, cerebrovascular disease, peripheral vascular disease, and anemia. Mortality was determined over a median of 3.7 years of follow-up. Results The prevalence of eGFRCKD-EPI <60 mL/min/1.73 m2 was 14.3% compared with 16.8% using eGFRMDRD . Using eGFRCKD-EPI , 20,355 participants (17.5%) were reclassified to higher eGFR categories, and 3,107 (2.7%), to lower categories. Participants reclassified upward were younger and less likely to have chronic conditions, with a lower risk of mortality. A total of 3,601 deaths (3.1%) were reported. Compared with participants classified to eGFR of 45-59 mL/min/1.73 m2 using both equations, those with eGFRCKD-EPI of 60-89 mL/min/1.73 m2 had a lower mortality incidence rate (6.4 95% CI, 5.1-7.7 vs 18.5 95% CI, 17.1-19.9). Results were similar for all eGFR categories. Net reclassification improvement was 0.159 ( P < 0.001). Conclusions The CKD-EPI equation reclassifies people at lower risk of CKD and death into higher eGFR categories, suggesting more accurate categorization. The CKD-EPI equation will be used to report eGFR in KEEP.
Black-white disparities in mortality persist after adjustment for socioeconomic status and health behaviors. We examined whether allostatic load, the physiological profile influenced by repeated or ...chronic life stressors, is associated with black-white mortality disparities independent of traditional sociobehavioral risk factors.
We studied 4515 blacks and whites aged 35 to 64 years from the third National Health and Nutrition Examination Survey (1988-1994), using the linked mortality file, to ascertain participant deaths through 2006. We estimated unadjusted sex-specific black-white disparities in cardiovascular/diabetes-related mortality and noninjury mortality. We constructed baseline allostatic load scores based on 10 biomarkers and examined attenuation of mortality disparities in 4 sets of sex-stratified multivariate models, sequentially adding risk factors: (1) age/clinical conditions, (2) socioeconomic status (SES) variables, (3) health behaviors, and (4) allostatic load.
Blacks had higher allostatic load scores than whites; for men, 2.5 vs 2.1, p < .01; and women, 2.6 vs 1.9, p < .01. For cardiovascular/diabetes-related mortality among women, the magnitude of the disparity after adjustment for other risk factors (hazard ratio HR, 1.63; 95% confidence interval CI, 0.96-2.75) decreased after adjustment for allostatic load (HR, 1.15; 95% CI, 0.70-1.88). For noninjury mortality among women, the magnitude of the disparity after adjustment for other risk factors (HR, 1.43; 95% CI, 1.00-2.04) also decreased after adjustment for allostatic load (HR, 1.26; 95% CI, 0.90-1.78). For men, disparities were attenuated but persisted after adjustment for allostatic load.
Allostatic load burden partially explains higher mortality among blacks, independent of SES and health behaviors. These findings underscore the importance of chronic physiologic stressors as a negative influence on the health and lifespan of blacks in the United States.
Background In maintenance hemodialysis (HD) patients, overweight and obesity are associated with survival advantages. Given the greater survival of maintenance HD patients who are minorities, we ...hypothesized that increased body mass index (BMI) is associated more strongly with lower mortality in blacks and Hispanics relative to non-Hispanic whites. Study Design Retrospective cohort study. Setting & Participants We examined a 6-year (2001-2007) cohort of 109,605 maintenance HD patients including 39,090 blacks, 17,417 Hispanics, and 53,098 non-Hispanic white maintenance HD outpatients from DaVita dialysis clinics. Cox proportional hazards models examined the association between BMI and survival. Predictors Race and BMI. Outcomes All-cause mortality. Results Patients had a mean age of 62 ± 15 (standard deviation) years and included 45% women and 45% patients with diabetes. Across 10 a priori–selected BMI categories (<18-≥40 kg/m2 ), higher BMI was associated with greater survival in all 3 racial/ethnic groups. However, Hispanic and black patients experienced higher survival gains compared with non-Hispanic whites across higher BMI categories. Hispanics and blacks in the ≥40-kg/m2 category had the largest adjusted decrease in death HR with increasing BMI (0.57 95% CI, 0.49-0.68 and 0.63 95% CI, 0.58-0.70, respectively) compared with non-Hispanic whites in the 23- to 25-kg/m2 group (reference category). In linear models, although the inverse BMI-mortality association was observed for all subgroups, overall black maintenance HD patients showed the largest consistent decrease in death HR with increasing BMI. Limitations Race and ethnicity categories were based on self-identified data. Conclusions Whereas the survival advantage of high BMI is consistent across all racial/ethnic groups, black maintenance HD patients had the strongest and most consistent association of higher BMI with improved survival.
Background Uninsured adults in the United States have poor access to health care services and worse health outcomes than insured adults. Little is known about the association between lack of ...insurance and chronic kidney disease (CKD) progression to end-stage renal disease (ESRD) or death in patients at high risk of kidney disease. We used 2000-2011 data from the National Kidney Foundation's Kidney Early Evaluation Program (KEEP) to examine this association. Methods The study population included KEEP participants younger than 65 years. Outcomes were time to ESRD (chronic kidney failure treated by renal replacement therapy) and time to death. Incident ESRD was ascertained by linkage to the US Renal Data System, and vital status, by linkage to the Social Security Administration Death Master File. We used Cox proportional hazard regression to examine the association between insurance and risk of death or ESRD after adjusting for demographic variables. Results Of 86,588 participants, 27.8% had no form of insurance, 10.3% had public insurance, and 61.9% had private insurance; 15.0% had CKD (defined as estimated glomerular filtration rate <60 mL/min/1.73 m2 or urine albumin-creatinine ratio ≥30 mg/g), 63.3% had hypertension, and 27.7% had diabetes. Of participants with CKD, 29.3% had no health insurance. Participants without insurance were younger, more likely to be Hispanic and to have 12 or fewer years of education, and less likely to have seen a physician in the past year. After adjustment for demographic characteristics, uninsured KEEP participants were 82% more likely than privately insured participants to die (HR, 1.82; 95% CI, 1.56-2.12; P < 0.001) and 72% more likely to develop ESRD (HR, 1.72; 95% CI, 1.33-2.22; P < 0.001). The association between insurance and outcomes varied by CKD stage. Conclusions Lack of insurance is an independent risk factor for early death and ESRD in this population at high risk of kidney disease. Considering the high morbidity and mortality and increasing cost associated with ESRD, access to appropriate health insurance coverage is warranted.
Background Observational studies indicate greater survival in African American and Hispanic maintenance hemodialysis patients compared with their non-Hispanic white counterparts, although African ...Americans have shorter life expectancy than whites in the general population. We hypothesized that this apparent survival advantage is due to a more favorable nutritional/inflammatory profile in minority hemodialysis patients. Study Design We examined the association between race/ethnicity and 5-year survival before and after adjustment for case-mix and surrogates of the malnutrition-inflammation complex syndrome (MICS) using Cox regression with or without matched sampling in a large cohort of adult hemodialysis patients. Setting & Participants 124,029 adult hemodialysis patients, including 16% Hispanics, 49% non-Hispanic whites, and 35% African Americans. Predictors Race/ethnicity before and after adjustment for MICS, including values for body mass index, serum albumin, total iron-binding capacity, ferritin, creatinine, phosphorus, calcium, bicarbonate, white blood cell count, lymphocyte percentage, hemoglobin, and protein intake. Outcomes 5-year (July 2001 to June 2006) survival. Results In dialysis patients, blacks and Hispanics had lower mortality overall than non-Hispanic whites after traditional case-mix adjustment. However, after additional control for MICS, Hispanics had mortality similar to non-Hispanic whites, and African Americans had even higher mortality. Unadjusted, case-mix–, and MICS-adjusted HRs for African Americans versus whites were 0.68 (95% CI, 0.66-0.69), 0.89 (95% CI, 0.86-0.91), and 1.06 (95% CI, 1.03-1.09) in the unmatched cohort and, 0.95 (95% CI, 0.90-0.99), 0.89 (95% CI, 0.84-0.94), and 1.16 (95% CI, 1.07-1.26) in the matched cohort, and for Hispanics versus whites, 0.66 (95% CI, 0.64-0.69), 0.84 (95% CI, 0.81-0.87), and 0.97 (95% CI, 0.94-1.00) in the unmatched cohort and 0.89 (95% CI, 0.84-0.95), 0.88 (95% CI, 0.83-0.95), and 0.98 (95% CI, 0.91-1.06) in the matched cohort, respectively. Limitations Adjustment cannot be made for unmeasured confounders. Conclusions Survival advantages of African American and Hispanic hemodialysis patients may be related to differences in nutritional and inflammatory status. Further studies are required to explore these differences.
Background Early identification of anemia of chronic kidney disease may be important for the development of preventive strategies. We compared anemia prevalence and characteristics in the National ...Kidney Foundation Kidney Early Evaluation Program (KEEP) and National Health and Nutrition Examination Survey (NHANES) 1999-2004 populations. Methods Clinical, demographic, and laboratory data were collected from August 2000 to December 31, 2006, from participants in KEEP, a community-based health-screening program targeting individuals 18 years and older with diabetes, hypertension, or family history of kidney disease, diabetes, or hypertension. Anemia was defined as hemoglobin level less than 13.5 g/dL for men and less than 12.0 g/dL for women (Kidney Disease Outcomes Quality Initiative KDOQI 2006) or less than 13.0 g/dL for men and less than 12.0 g/dL for women (World Health Organization WHO). Results In KEEP (n = 70,069), 68.3% of participants, and in NHANES (n = 17,061), 52% of participants, were women. African Americans represented 33.9% of the KEEP and 11.2% of the NHANES cohorts, and Hispanics comprised 12.4% of KEEP and 13.2% of NHANES. Using the KDOQI classification, anemia was present in 13.9% and 6.3% of KEEP and NHANES participants, whereas using the WHO classification, anemia was present in 11.8% and 5.3%, respectively. In adjusted analysis of KEEP data, KDOQI-defined anemia was significantly more likely in men (odds ratio OR, 1.30; 95% confidence interval CI, 1.23 to 1.37); this pattern was reversed when using WHO-defined anemia (OR, 0.68; 95% CI, 0.64 to 0.72). Adjusted odds of anemia were greater for African American than white KEEP participants (OR, 2.98; 95% CI, 2.80 to 3.16; OR, 3.00; 95% CI, 2.81 to 3.20 for KDOQI- and WHO-defined anemia, respectively). Conclusion Anemia was twice as common in the targeted KEEP chronic kidney disease screening program cohort than in the NHANES sample population. African Americans had a 3-fold increased likelihood of anemia compared with whites. Targeted screening can identify anemia in a high-risk population.
Background Recent reports have suggested a close relationship between education and health, including mortality, in the United States. Study Design Observational cohort. Setting & Participants We ...studied 61,457 participants enrolled in a national health screening initiative, the National Kidney Foundation's Kidney Early Evaluation Program (KEEP). Predictor Self-reported educational attainment. Outcomes Chronic diseases (hypertension, diabetes, cardiovascular disease, reduced kidney function, and albuminuria) and mortality. Measurements We evaluated cross-sectional associations between self-reported educational attainment with the chronic diseases listed using logistic regression models adjusted for demographics, access to care, behaviors, and comorbid conditions. The association of educational attainment with survival was determined using multivariable Cox proportional hazards regression. Results Higher educational attainment was associated with a lower prevalence of each of the chronic conditions listed. In multivariable models, compared with persons not completing high school, college graduates had a lower risk of each chronic condition, ranging from 11% lower odds of decreased kidney function to 37% lower odds of cardiovascular disease. During a mean follow-up of 3.9 (median, 3.7) years, 2,384 (4%) deaths occurred. In the fully adjusted Cox model, those who had completed college had 24% lower mortality compared with participants who had completed at least some high school. Limitations Lack of income data does not allow us to disentangle the independent effects of education from income. Conclusions In this diverse contemporary cohort, higher educational attainment was associated independently with a lower prevalence of chronic diseases and short-term mortality in all age and race/ethnicity groups.
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