Prognostic value of 24-hour ambulatory blood pressure monitoring and of night/day ratio in nondiabetic, cardiovascular events-free hemodialysis patients

Abstract

The use of 24-hour ambulatory blood pressure monitoring is increasing in end-stage renal disease (ESRD) patients but the prediction power for cardiovascular complications of time-averaged ambulatory blood pressure components has been little investigated in these patients. We analyzed the prognostic power of 24-hour ambulatory blood pressure monitoring for all-cause and cardiovascular mortality in 168 nondiabetic, events-free hemodialysis patients selected from a total dialysis population of about 450 patients. During the follow-up period (38 +/- 22 months), 48 patients died, 29 of them of cardiovascular causes. On univariate Cox regression analyses, the night/day systolic ratio resulted to be the sole blood pressure indicator to be associated with all-cause and cardiovascular mortality while left ventricular hypertrophy (LVH) was a strong predictor of these outcomes. In multivariable Cox models not including LVH, the night/day systolic ratio maintained an independent prognostic value for incident outcomes. However, when both risk factors, LVH and night/day systolic ratio, were introduced into Cox models, LVH was no longer a significant predictor while the night/day systolic ratio became a predictor of marginal statistical significance. The night/day ratio emerges as the sole ambulatory blood pressure monitoring-derived indicator providing significant prognostic information in patients with ESRD. However, this indicator as well as LVH loses substantial prediction power in statistical models including both risk factors. The results suggest that the night/day systolic ratio and LVH provide overlapping prognostic information, a phenomenon in keeping with the hypothesis that they represent a common pathway leading to adverse outcomes in ESRD.