Increased Nighttime Pulse Pressure Variability but Not Ambulatory Blood Pressure Levels Predicts 14-Year All-Cause Mortality in Patients on Hemodialysis

Abstract

Increased short-term blood pressure (BP) variability is associated with adverse cardiovascular outcomes in patients with hypertension. The present study investigated the long-term prognostic significance of the short-term blood pressure variability in patients on hemodialysis. A total of 149 patients (53.0% male; mean age: 54.5±15.1 years) receiving regular hemodialysis for >6 months were enrolled. They completed a 44-hour (excluding the hemodialysis session) ambulatory BP monitoring and comprehensive hemodynamic assessments, including carotid-femoral pulse wave velocity and pressure waveform decomposition (forward and backward wave amplitude). Blood pressure variability parameters, including average real variability (ARV) of systolic BP, diastolic BP, and pulse pressure (ARVp) during daytime, nighttime, and overall 44 hours were calculated. During a median follow-up of 14 years, 78 deaths (52.4%) were confirmed. In multivariable Cox regression analysis, none of the ambulatory BP parameters were predictive of mortality. In contrast, nighttime ARVp was consistently and significantly associated with all-cause mortality in multivariable Cox models adjusting for age, sex, albumin, hemodialysis treatment adequacy, and 44-hour systolic BP (continuous variable analysis, per 1-SD, hazard ratio=1.348; 95% CI, 1.029-1.767; categorical variable analysis, ≥8.5 versus <8.5 mm Hg; hazard ratio=1.825; 95% CI, 1.074-3.103). Forward wave amplitude and 44-hour systolic BP were identified as the 2 most important determinants of nighttime ARVp. Addition of nighttime ARVp to the base model significantly improved prediction of all-cause mortality (Net reclassification improvement =0.198; P=0.0012). In hemodialysis patients, increased short-term nighttime pulse pressure variability but not ambulatory BP levels were significantly predictive of long-term all-cause mortality.