Abstract
We aim to determine if visit-to-visit blood pressure variability (BPV) adds prognostic value for all-cause mortality independently of the Framingham risk score (FRS) in the systolic blood pressure intervention trial (SPRINT). We defined BPV as variability independent of the mean (VIM) and the difference of maximum minus minimum (MMD) of the systolic blood pressure (SBP). Multivariable Cox proportional hazards models were used to estimate the hazard ratio (HR) and 95% confidence interval (CI). Based on FRS stratification, there were 1035, 2911, and 4050 participants in the low-, intermediate-, and high-risk groups, respectively. During the trial, 230 deaths occurred since the 12th month with an average follow-up of 2.5 years. In continuous analysis, 1-SD increase of SBP VIM and MMD were significantly associated with all-cause mortality (HR 1.18, 95% CI 1.05-1.32, p = .005; and HR 1.21, 95% CI 1.09-1.35, p < .001, respectively). In category analysis, the highest quintile of BPV compared with the lowest quintile had significantly higher risk of all-cause mortality. Cross-tabulation analysis showed that the 3rd tertile of SBP VIM in the high-risk group had the highest HR of all-cause mortality in total population (HR 4.99; 95% CI 1.57-15.90; p = .007), as well as in intensive-therapy group (HR 7.48; 95% CI 1.01-55.45; p = .05) analyzed separately. Cross-tabulation analysis of SBP MMD had the same pattern as VIM showed above. In conclusion, visit-to-visit BPV was an independent predictor of all-cause mortality, when accounting for conventional risk factors or FRS. BPV combined with FRS conferred an increased risk for all-cause mortality in the SPRINT trial.