THE JOINT EFFECTS OF RACE AND AGE ON THE RISK OF END-STAGE RENAL-DISEASE ATTRIBUTED TO HYPERTENSION

To describe the joint effects of race and age on the risk of end-stage renal disease (ESRD) attributed to hypertension (ESRD-HT), we analyze d data for white and black adults, 20 to 84 years of age, reported by the United States Renal Data System during the period 1987 to 1990. Th e risk of ESRD-HT increased substantially with age for both blacks and whites; however, at each age, the risk was greater for blacks. A more in-depth description of the combination of effects involving race and age on ESRD-HT incidence was provided by two models of joint effects, one additive and the other multiplicative. Both models used the 20- t o 24-year age group as the referent. Under the additive model the risk of ESRD-HT in blacks attributable to the joint effects between race a nd age increased continuously from younger to older groups. This indic ates that although ESRD-HT risk increases with age for both blacks and whites, the increase for blacks is greater than expected if the effec ts of race were independent of the effects of age. However, the multip licative model indicated that the proportional increase with age in ES RD-HT risk among blacks, as compared with whites, was more striking fo r younger ages (less than or equal to 50 years among women and less th an or equal to 40 years among men), and especially so for men. This su ggests a more accelerated course of hypertension toward ESRD for black s (especially younger men) than for whites. A conceptual model to expl ain these patterns of race-age joint effects is proposed. The model co nsiders two pathogenic patterns of progression to ESRD among hypertens ive patients: (1) a rapidly progressive disease, particularly for youn ger black men, and (2) a slower progressive disease that culminates in ESRD at older ages. The implications of this conceptual model for fut ure research, and the empirical findings on which it is based, are dis cussed. (C) 1994 by the National Kidney Foundation, Inc.