Associations Between Five-year Blood Pressure Variability and Risk of Cardiovascular Events and Mortality: A Territory-wide Family Medicine Cohort Study

Introduction: Blood pressure variability, in addition to blood pressure itself, has been used as a predictor for mortality. This study examined the predictive power of baseline/latest/mean/median blood pressure and blood pressure variability measures for all-cause mortality and adverse cardiovascular outcomes. Methods: The retrospective observational study analyzed patients who presented to family medicine clinics between 1st January, 2000 and 31st December, 2001. Blood pressure measurements were obtained over a five-year period. Standard deviation (SD), root mean square (RMS), coefficient of variation (CV) and a variability score (number of ≥ 5 mmHg blood pressure change) were used as measures of blood pressure variability. The primary outcome was all-cause mortality and the secondary outcomes were heart failure, acute myocardial infarction, and transient ischemic attack (TIA)/ stroke, with follow-up until 31 December 2019. Results: This study included 37,540 patients (n ¼ 29,597 patients with ≥ 3 blood pressure measurements). A nonlinear inverse U-shaped relationship was observed between baseline/latest/maximum/minimum/mean/median/RMS measures of diastolic blood pressure and time-to-death for all-cause mortality (P < 0.001). Higher variance/SD/CV/variability score of both systolic and diastolic blood pressure was significantly associated with increased risks of all-cause mortality and heart failure, acute myocardial infarction and TIA/stroke (P < 0.001). Low baseline/latest/maximum/minimum/mean/median/ RMS systolic blood pressure was significantly associated with shorter time-to-death for all-cause mortality (P < 0.001). Conclusion: Nonlinear inverse U-shaped relationships were observed between blood pressure and its variability measures and all-cause mortality. Higher blood pressure variability was associated with increased risk of all-cause mortality, heart failure, acute myocardial infarction and TIA/stroke.