Risk factors for the decline of renal function in hypertensive men: A non-concurrent cohort study
Description
Objective. To examine the relationship between race, blood pressure (BP), and illicit drug use with the decline in renal function in hypertensive males Methods. This study uses a non-concurrent cohort study design with repeated measurements on risk factors and outcome over follow-up. Data was collected by abstraction and patient interviews of 890 male hypertension patients attending the Hypertension Clinic at the Veterans Administration Medical Center of New Orleans. Change in renal function was assessed by the annual change in the reciprocal of serum creatinine and by early decline in renal function (defined as a change in serum creatinine over follow-up of ≥ 0.6 mg/dl). Mixed effects models were used to assess the relationship between risk factors and annual change in the reciprocal of serum creatinine. Cox models were used to examine the relationship between risk factors and incidence of early decline in renal function Results. The annual change in systolic BP, diastolic BP and serum creatinine were -0.983 mm Hg/year, -1.75 mm Hg/year, and 0.021 mg/dl/year, respectively, over a maximum of 23 years of follow-up in our study population of 816 hypertensive, predominantly African-American men. The incidence of early decline in renal function over 15 years of follow-up was 17.8% for African-Americans and 15.6% for white, although this difference was not statistically significant. The crude and multivariate adjusted relative risks of early decline in renal function for African-Americans compared to whites was also not statistically significant among the study participants, who have similar SES, access to health and health care provider. Treated systolic and diastolic BPs, as well as BP control of ≥160/95 (systolic/diastolic) compared to <140/90, were significantly and positively associated with early decline in renal function. A one standard deviation difference in systolic BP (18 mmHg) and diastolic BP (10mmHg) was associated with a 1.9 and 1.4-fold greater risk of early renal function decline (both p < 0.01), respectively. BP control of >160/95 (systolic/diastolic) compared to <140/90 was associated with a 4.3-fold greater risk of early decline in renal function (p < 0.001); and BP control of 140--159/90--94 compared to <140/90 was associated with a 2.4-fold greater risk of early decline in renal function (p < 0.05) after adjustment for important covariables. Our study also demonstrated that the use of illicit drugs was associated with a 2.3-fold greater risk of developing early renal function decline (p < 0.05). Specifically, cocaine/crack users and hallucinogen users had a 3.0 and 3.9-fold greater risk of early decline in renal function (both p < 0.05), respectively, after adjusting for important covariables Conclusions. Our study suggests that modifiable risk factors such as SES, access to health care and health care provider may be responsible for the excess risk of renal disease experienced by African-Americans. In addition, our results indicate that more aggressive control of blood pressure among hypertensive men may slow the progression of renal disease and may delay the onset of end-stage renal disease. Finally, we showed that the use of illicit drugs, specifically cocaine/crack and hallucinogens, may be associated with early deterioration of renal function