Renal function change in hypertensive members of the Multiple Risk Factor Intervention Trial. Racial and treatment effects. The MRFIT Research Group

Abstract

Objective: To evaluate the contribution of mild to moderate hypertension to progressive loss of renal function by analysis of renal function data from the Multiple Risk Factor Intervention Trial.

Design: The cohort of men with mild to moderate hypertension (baseline diastolic blood pressure > or = 90 mm Hg), randomized to a special intervention (SI) group or usual care (UC) group, were examined for change in renal function based on individual reciprocal creatinine slopes over an average of 7 years' follow-up as the outcome measure. Contribution of blood pressure control during follow-up, age, race, and blood pressure at entry were assessed.

Participants: The cohort of 5524 (463 black, 5061 nonblack) hypertensive men receiving no therapy at entry provided the data for the present analysis.

Results: Blood pressure control was similar for black and white participants, but significant decline in reciprocal creatinine slope was found for black men (mean slope, -0.0090 +/- 0.0013 dL/mg/y) compared with white men (+0.0018 +/- 0.0004 dL/mg/y) (P < .001 for difference between blacks and whites). Decline in renal function was also greater among individuals with elevated systolic (P < .001) as well as diastolic blood pressure (P < .001), and older individuals (P < .001). No difference between the SI and UC groups was seen in reciprocal creatinine slopes, but in both groups combined, treatment that maintained diastolic blood pressure below an average value of 95 mm Hg was associated with stable or improving renal function, whereas participants whose blood pressure remained 95 mm Hg or greater continued to decline at -0.0013 +/- 0.0009 dL/mg/y (P = .007 for difference). Separate examination of the subset of black men (n = 463) failed to show such a difference.

Conclusions: Effective blood pressure control was associated with stable or improving renal function in nonblacks but not in blacks. These findings emphasize the importance of blood pressure control to maintain adequate renal function in hypertensive white men and raise important questions about the relationship of pressure reduction and renal function change in blacks.