Autosomal dominant polycystic kidney disease in blacks: Clinical course and effects of sickle-cell hemoglobin

Autosomal dominant polycystic kidney disease (ADPKD) is a frequent cause of ESRD, but its frequency in blacks has not been well delineated and its course and the effects of sickle hemoglobin in this disease in blacks have not been previously reported. The occurrence of ADPKD in blacks and whites was determined in two ESRD populations: all ESRD patients seen over a 16-yr period in one area of Southeast Tennessee and all ESRD patients in 15 hemodialysis units in Tennessee and Atlanta, GA. The frequency of sickle hemoglobin was determined and compared in a group of nonrelated blacks with ESRD with and without ADPKD. The age at onset of ESRD and factors that might affect ADPKD such as gender, hypertension, and hemoglobin type were examined. ADPKD was a less frequent cause of ESRD in blacks than whites (1.4 versus 6.8%). However, after adjusting for the population rate, the incidence rates in blacks and whites were similar (0.48 and 0.47 of 100,000). There was a higher incidence of sickle hemoglobin in nonrelated blacks with ADPKD versus other black ESRD patients (50 versus 7.5%; P<0.005). Blacks had an earlier onset of ESRD than whites (43.2 versus 55.4 yr; P < 0.0001), as did blacks with sickle-cell trait versus blacks without (38.2 versus 48.1 yr; P< 0.003). In this population, hypertension and gender had no effect on the onset of ESRD. ADPKD accounted for a smaller percentage of blacks than whites with ESRD because of the high percentage of blacks with renal disease from other causes. However, the frequency of ESRD due to ADPKD was similar in blacks and whites. Sickle-cell hemoglobin occurred more frequently than expected, and there was evidence of more severe disease as measured by earlier onset of ESRD in blacks when compared with whites and blacks with sickle-cell trait when compared with blacks without the trait.