[Association between race and incidence of end-stage renal disease secondary to glomerulonephritis: influence of the histologic type and presence of arterial hypertension]

Abstract

Objective: To assess, retrospectively, the association between race and incidence of end-stage renal disease (ESRD) in patients with glomerulonephritis in a University Hospital of Bahia, Brazil.

Methods: The sample was comprised of 79 patients with focal segmental glomerulosclerosis (FSG), 50 with membranoproliferative glomerulonephritis (MPGN) and 49 with other types of glomerulonephritis (OTGN), followed-up between 1970 and 1996 for at least 6 months. It was not included patients with acute glomerulonephritis, minimal change disease, crescentic glomerulonephritis, connective tissue diseases or patients with serum creatinine level greater than or equal to 4.0 mg/dl. The patients were classified according to race as caucasian (white), mulatto or negro. For patients older than 18 yr, not taking antihypertensives drugs, hypertension was defined as a mean of three blood pressure measurements greater than or equal to 140 mmHg for systolic or 90 mmHg for diastolic; for ages </= 18 years. The definition was based on criteria recommended by the Task Force on Blood Pressure in Children.

Results: In the normotensive group, the incidence of ESRD was 72% lower in mulattos and negroes (relative risk (RR)=0.28; 95% confidence interval (CI)=0.11-0.67). In the group with hypertension, the direction of association between race and ESRD was opposite to that observed in the normotensive group (RR=1.49; 95% CI= 0.68-4.34). The modification in the RR depending on the presence or the absence of hypertension was statistically significant (p=0.01). In the normotensive group the RR shifted toward the null hypothesis after the inclusion of histologic type in the Cox model.

Conclusions: Among normotensive patients with glomerulonephritis the incidence of ESRD was greater in caucasians (whites) than in negroes or mulattoes. By contrast among hypertensive patients there was a trend for a higher risk of ESRD in negroes. The study suggests that hypertension and the histologic type of glomerulonephritis influence the association between race and ESRD.