Blood Pressure Indexes Associated With Mortality and Cardiovascular Outcomes

Abstract

To the Editor Dr Yang and colleagues reported that higher 24-hour and nighttime blood pressure (BP) measurements were significantly associated with greater risks of death and a composite cardiovascular outcome, even after adjusting for other office-based or ambulatory BP measurements.¹ We have several comments on the study. First, after further adjustment for 24-hour systolic BP in multivariable analyses, daytime BP was inversely associated with the risk of mortality (hazard ratio, 0.78; 95% CI, 0.69-0.88) and cardiovascular outcomes (hazard ratio, 0.77; 95% CI, 0.67-0.89). This suggests that patients with higher daytime BP have improved outcomes. Could such counterintuitive results be caused by overadjustment of the Cox regression model?