Differences in survival between black and white patients with diabetic end-stage renal disease.

OBJECTIVE: To evaluate whether the longer survival of blacks with diabetic end-stage renal disease (ESRD) relative to whites is due to racial differences in type of diabetes, comorbidity at ESRD onset, and ESRD treatment modality and to examine whether survival differences between blacks and whites occur only in certain population subgroups. RESEARCH DESIGN AND METHODS: The Michigan Kidney Registry was used to ascertain all blacks and whites (n = 594) with diabetic ESRD in southeastern Michigan, with ESRD onset at age < 65 years during 1974-1983. Patients were followed through 1988. Medical records were abstracted for type of diabetes, comorbidity at ESRD onset, and other factors. RESULTS: Median survival among insulin-dependent diabetes mellitus patients was 27 months in blacks and 17 months in whites, and among non-insulin-dependent diabetes mellitus patients was 30 months in blacks and 16 months in whites. After adjustment for confounding factors by Cox proportional hazards analysis, the death rate was 45% lower in blacks than in whites on dialysis (relative death rate [RDR] = 0.55, 95% confidence interval [CI] = 0.44-0.69), but was similar in blacks and whites with a renal transplant (RDR = 0.99, 95% CI = 0.64-1.52). Compared with dialysis, transplantation was associated with lower mortality in both races (white, RDR = 0.50, 95% CI = 0.36-0.70; blacks, RDR = 0.89, 95% CI = 0.60-1.34), although the effect was not statistically significant in blacks. Racial differences in survival did not vary by type of diabetes or any additional factor. CONCLUSIONS: Survival after ESRD onset is longer in blacks than in whites treated with dialysis, even after adjusting for comorbidity and other factors that affect survival. Survival does not differ by race among transplant patients.

Variance estimation for complex surveys using replication techniques.

The analysis of survey data requires the application of special methods to deal appropriately with the effects of the sample design on the properties of estimators and test statistics. The class of replication techniques represents one approach to handling this problem. This paper discusses the use of these techniques for estimating sampling variances, and the use of such variance estimates in drawing inferences from survey data. The techniques of the jackknife, balanced repeated replication (balanced half-samples), and the bootstrap are described, and the properties of these methods are summarized. Several examples from the literature of the use of replication in analysing large complex surveys are outlined.

Effect of multiple risk factors on differences between blacks and whites in the prevalence of non-insulin-dependent diabetes mellitus in the United States.

The higher prevalence of non-insulin-dependent diabetes mellitus (NIDDM) in US blacks as compared with whites may be due to a higher frequency of NIDDM risk factors in blacks, a higher inherent susceptibility to NIDDM among blacks, or the risk factors' having a greater effect in blacks. The authors evaluated 4,379 subjects from the Second National Health and Nutrition Examination Survey (1976-1980) for whom NIDDM was ascertained by medical history and oral glucose tolerance test, and for whom data on a number of risk factors were available. The prevalence of NIDDM was 60% higher in blacks than in whites (p < 0.001) and was highest in black women. Although most risk factors for NIDDM were more common in blacks, this higher frequency did not completely explain the racial disparity in the prevalence of NIDDM. After adjustment for all risk factors by logistic regression, an elevated risk of NIDDM was particularly evident at higher obesity levels in blacks as compared with whites; the odds were 70% higher for blacks at a percentage of desirable weight of 150 (95% confidence interval 1.1-2.8). The risk of NIDDM associated with obesity was greatest in black women: The odds in this group were sevenfold higher at a percentage of desirable weight of 150 versus 100 (95% confidence interval 2.6-18.8). The possibility of racial differences in metabolic adaptation to obesity highlights the importance of preventing this condition in blacks, particularly in black women.