Within-Visit Blood Pressure Variability and All-Cause and Stroke Mortality: Thai Epidemiologic Stroke Study

Abstract

Introduction: The association between within-visit blood pressure variability (BPV) and all-cause and stroke mortality remains uncertain. The aim of our study was to assess the association of within-visit BPV with all-cause and stroke mortality. Methods: The study was conducted among participants from Thai Epidemiologic Stroke Study, which is a prospective community-based cohort study that recruited participants from the general population from five regions of Thailand. This study included 19,614 participants aged 45–80 years, who were free of stroke and had three blood pressure (BP) measurements, taken 1 min apart, at baseline. Within-visit systolic blood pressure (SBP) and diastolic blood pressure (DBP) variability were expressed as the maximum absolute difference (MAD) between any two readings among the three repeated sequential measurements of SBP and DBP, respectively. The participants were followed up for mortality. Cox regression analysis was used to identify the association of within-visit BPV with all-cause and stroke mortality. Hazard ratio (HR) and 95% confidence intervals were used to illustrate the associations. Sensitivity analysis restricted to participants with mean SBP above 130 mm Hg and mean DBP above 90 mm Hg (n = 1,895) was performed. Results: During a median follow-up of 11.1 years, 305 participants died of stroke, and 3,173 participants died of nonstroke cause. In unadjusted analyses, high within-visit MAD of SBP was significantly associated with all-cause (HR, 1.19; 95% CI, 1.09–1.31; p < 0.001) and stroke mortality (HR, 1.87; 95% CI, 1.35–2.59; p < 0.001); high within-visit MAD of DBP was also significantly associated with all-cause mortality (HR, 1.19; 95% CI, 1.08–1.31; p < 0.001), in quartile 4 versus quartile 1. These associations did not persist after further adjustment for sex, age, and other potential confounders including mean BP. However, sensitivity analysis showed some inconsistent results regarding associations of within-visit MAD of SBP and DBP with all-cause and stroke mortality, respectively. Conclusion: In general population, within-visit systolic BPV and within-visit diastolic BPV do not have prognostic significance on stroke mortality and all-cause mortality, respectively.