1. From a post-hoc analysis of an antihypertensive therapy trial, increased variability in blood pressure was associated with increased risk for mortality and stroke.
Evidence Rating Level: 2 (Good)
Study Rundown: Although elevated blood pressure is a known risk factor for cardiovascular disease, blood pressure measurements often vary between outpatient visits. However, the association between blood pressure variability and negative outcomes remains unclear. This study analyzed data from a large clinical trial in which participants’ blood pressure was measured every four months for over two years. After adjustment for a number of factors known to be associated with heart disease and hypertension, as well as average blood pressure, visit-to-visit variability (VVV) in blood pressure between study visits was analyzed in relation to cardiovascular disease outcomes and death from any cause. Patients with the highest amount of VVV had significantly increased rates of fatal coronary heart disease or nonfatal heart attack, stroke, and all-cause mortality compared to patients with the lowest amount of VVV. Notably, this study only followed patients for five years after the end of blood pressure assessments, a relatively short period of time to determine cardiovascular outcomes. In addition, a complete series of blood pressure measurements was missing from one fifth of participants, which, although accounted for in the study’s analysis, potentially limits its results. Nevertheless, the results from this study suggest that in addition to blood pressure, blood pressure variability may be a significant risk factor for cardiovascular disease and death.
In-Depth [prospective cohort study]: This study was a post-hoc analysis of data from the ALLHAT (Antihypertensive and Lipid-Lowering Treatment to Prevent Heart Attack Trial), a prospective, community-based, outpatient trial of antihypertensive medications. Participants underwent at least five blood pressure measurements over two years. Visit-to-visit variability (VVV) in systolic blood pressure was defined as the standard deviation (SD) in blood pressure for each participant across study visits, and SD quintiles were compared. After full adjustment for an extensive list of cofounders, participants in the highest quintile of blood pressure VVV had a significantly higher incidence of fatal coronary heart disease or nonfatal myocardial infarction (HR 1.30, 95%CI 1.06-1.59), stroke (HR 1.46, 95%CI 1.06-2.01), and all-cause mortality (HR 1.58, 95%CI 1.32-1.90), compared to participants in the lowest quintile of blood pressure VVV. Notably, there was no significant difference in incidence of heart failure between highest and lowest quintiles in the fully adjusted model of blood pressure VVV.
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