Superiority of Ambulatory Over Clinic Blood Pressure Measurement in Predicting Mortality

TLDR

The study aimed to determine whether ambulatory blood pressure measurement predicts total and cardiovascular mortality beyond clinic blood pressure and other risk factors in 5,292 untreated hypertensive patients. Time‑to‑event analyses used Cox regression to model mortality outcomes with ambulatory blood pressure, adjusting for clinic blood pressure and baseline risk factors. In an 8.4‑year follow‑up of 5,292 patients, ambulatory blood pressure independently predicted cardiovascular mortality, with each 10‑mmHg increase in systolic BP raising risk by 12% daytime and 21% nighttime, and nighttime BP emerging as the most powerful predictor, demonstrating ambulatory measurement’s superiority over clinic readings.

Abstract

The purpose of this study was to determine if ambulatory blood pressure measurement predicted total and cardiovascular mortality over and beyond clinic blood pressure measurement and other cardiovascular risk factors; 5292 untreated hypertensive patients referred to a single blood pressure clinic who had clinic and ambulatory blood pressure measurement at baseline were followed up in a prospective study of mortality outcome. Multiple Cox regression was used to model time to total and cause-specific mortality for ambulatory blood pressure measurement while adjusting for clinic blood pressure measurement and other risk factors at baseline. There were 646 deaths (of which 389 were cardiovascular) during a median follow-up period of 8.4 years. With adjustment for gender, age, risk indices, and clinic blood pressure, higher mean values of ambulatory blood pressure were independent predictors for cardiovascular mortality. The relative hazard ratio for each 10-mm Hg increase in systolic blood pressure was 1.12 (1.06 to 1.18; P <0.001) for daytime and 1.21 (1.15 to 1.27; P <0.001) for nighttime systolic blood pressure. The hazard ratios for each 5-mm Hg increase in diastolic blood pressure were 1.02 (0.99 to 1.07; P =NS) for daytime and 1.09 (1.04 to 1.13; P <0.01) for nighttime diastolic pressures. The hazard ratios for nighttime ambulatory blood pressure remained significant after adjustment for daytime ambulatory blood pressure. These results have 2 important clinical messages: ambulatory measurement of blood pressure is superior to clinic measurement in predicting cardiovascular mortality, and nighttime blood pressure is the most potent predictor of outcome.