Prognostic importance of ambulatory blood pressure recordings in patients with chronic kidney disease

Abstract

Ambulatory systolic blood pressure (BP) correlates better with risk factors for progression of chronic kidney disease (CKD) compared to clinic measured BP, but its role in predicting end-stage renal disease (ESRD) and death in patients with CKD is unknown. In a cohort study of 217 Veterans with CKD BP was measured by ambulatory monitoring and in the clinic. Twenty-four hour ambulatory BP was 133.5 +/- 16.6/73.1 +/- 11.1 mm Hg and clinic BP was 155.2 +/- 25.6/84.7 +/- 14.2 mm Hg. The composite renal end point of ESRD or death over a median follow-up of 3.5 years occurred in 75 patients (34.5%), death occurred in 52 patients (24.0%), and ESRD in 36/178 patients (20.2%). Thirty-nine patients died before reaching ESRD. One standard deviation (s.d.) increase in systolic BP increased the risk of composite outcome to 1.69 (95% confidence interval (CI) 1.32-2.17) for standard clinic measurement and to 1.88 (95% CI 1.48-2.39) for 24 h ambulatory BP recording. One s.d. increase in 24 h ambulatory systolic BP increased the risk of ESRD to 3.04 (95% CI 2.13-4.35) and to 2.20 (95% CI 1.43-3.39) when adjusted for standard clinic systolic BP. Non-dipping was associated with increased risk of total mortality and composite end point. In patients with CKD, BPs obtained by ambulatory monitoring are a stronger predictor of ESRD or death compared to BPs obtained in the clinic. Systolic ambulatory BP and nondipping are independent predictors for ESRD after adjusting for clinic BP. However, adjustment for other risk factors for CKD progression removes the independent prognostic value of ambulatory BP.