Prognostic value of different indices of blood pressure variability in hypertensive patients

Abstract

Background: The independent prognostic significance of different indices of blood pressure (BP) variability is not clear. We investigated the prognostic value of BP variability estimated as s.d. or average real variability (ARV) of daytime and night time BP, in hypertensive patients.

Methods: The occurrence of fatal and nonfatal cardiovascular events was evaluated in 1,280 sequential hypertensive patients (550 initially untreated and 730 initially treated) aged > or =40 years. Subjects with s.d. or ARV of daytime or night time systolic or diastolic BP below or above the median were classified as having low or high BP variability.

Results: During the follow-up (4.75 +/- 1.8 years), 104 cardiovascular events occurred. The event rate per 100 patient-years was 1.71 in the global population. After adjustment for other covariates, Cox regression analysis showed that cardiovascular risk was higher in subjects with high ARV of daytime systolic BP in initially untreated, initially treated, and all the subjects (high vs. low ARV, hazard ratio (HR) 2.29 (1.06-4.94), HR 1.90 (1.06-3.39), and HR 2.07 (1.31-3.28), respectively). ARV of daytime diastolic BP and night time BP, and s.d. of daytime and night time BP were not significantly associated with risk or were not independent predictors of outcome.

Conclusions: In this study, high ARV of daytime systolic BP resulted in an independent predictor of cardiovascular risk in hypertensive patients, while high s.d. did not. Our data suggest that, in comparison to s.d., ARV could be a more appropriate index of BP variability and a more useful predictor of outcomes.