Discrepancy in the epidemiology of nondiabetic chronic renal insufficiency and end-stage renal disease in black and white Americans: the third National Health and Nutrition Examination Survey and United States Renal Data System.

BACKGROUND

Epidemiologic data regarding the prevalence of chronic renal insufficiency (CRI) [from the third National Health and Nutrition Examination Survey (NHANES III)] and the incidence of end-stage renal disease (ESRD) [from the United States Renal Data System (USRDS)] are available. However, reconciliation of these separate particulars has not been performed objectively. The present work examines the epidemiology of CRI of nondiabetic etiology and ESRD in black and white Americans aged 20 years or greater.

METHODS

Based on the incidence of ESRD in the study population (USRDS), the numbers of subjects with decreased Modification of Diet in Renal Disease (MDRD) glomerular filtration rate (GFR) <80 ml/min/1.73 m(2), <60 ml/min/1.73 m(2) and <30 ml/ min/1.73 m(2) in 1991 (on December 31 1991) were mathematically obtained based on a linear model of GFR decline. Similarly, the corresponding estimated prevalence figures of CRI were derived based on analyses of NHANES III data and the 1991 census counts of black and white Americans (aged 20 years or more). Unadjusted and adjusted (correcting for calibration differences between the NHANES III and MDRD laboratory) prevalences were calculated. Subsequently, the prevalence of different degrees of CRI based on the incidence of ESRD (USRDS) was compared to the corresponding figures of the estimated prevalence of CRI (NHANES III).

RESULTS

By analyses of USRDS data, on December 31 1991, the prevalence of different degrees of reduced GFR in the study population was estimated to be as follows: 396,863 subjects with GFR <80 ml/min/1.73 m(2); 272,932 subjects with GFR <60 ml/min/1.73 m(2), and 115,065 subjects with GFR <30 ml/min/1.73 m(2). Using actual NHANES III creatinine values, the prevalence of different degrees of CRI in the study population was estimated as follows: 92,595,211 people with GFR <80 ml/min/1.73 m(2); 20,754,099 people with GFR <60 ml/min/1.73 m(2), and 415,082 people with GFR <30 ml/min/1.73 m(2). The data suggest that approximately 0.43% of subjects with GFR <80 ml/min/1.73 m(2), 1.32% of subjects with GFR <60 ml/min/1.73 m(2) and 27.72% of subjects with GFR <30 ml/ min/1.73 m(2) reached ESRD (USRDS). Using adjusted NHANES III creatinine values (downwardly correcting the NHANES III creatinine values to account for calibration differences with the MDRD measurements), the prevalence of different degrees of CRI in the study population was estimated as follows: 28,512,939 people with MDRD GFR <80 ml/min/1.73 m(2) (17.86%); 5,364,136 people with MDRD GFR <60 ml/min/1.73 m(2) (3.36%), and 255,435 people with MDRD GFR <30 ml/min/1.73 m(2) (0.16%). Of these, about 1.39% of the people with MDRD GFR <80 ml/min/1.73 m(2), 5.09% of the people with MDRD GFR <60 ml/min/1.73 m(2) and 45.07% of the people with MDRD GFR <30 ml/min/1.73 m(2) in 1991 reached ESRD.

CONCLUSION

There is a major discrepancy in the epidemiology of nondiabetic CRI and ESRD amongst black and white Americans. The reasons for this need further study.