Baseline Diastolic BP and BP-Lowering Effects on Cardiovascular Outcomes and All-Cause Mortality: A Meta Analysis

Background: Lowering blood pressure (BP) in persons with low diastolic BP could be harmful. Hence, we examined whether baseline diastolic BP modifies the effects of BP lowering on clinical outcomes in a meta-analysis of five large BP lowering trials. Methods: In a study-level meta-analysis based on individual participant data of the Systolic Blood Pressure Intervention Trial (N = 9361), the Action to Control Cardiovascular Risk in Diabetes Blood Pressure (N = 2362), the Secondary Prevention of Small Subcortical Strokes (N = 3020), the African American Study of Kidney Disease and Hypertension (N = 1094) and the Modification of Diet in Renal Disease (N = 840) studies, we used DerSimonian-Laird random-effects models to examine the dependence of the effect of the BP lowering intervention on baseline diastolic BP for cardiovascular, all-cause mortality and kidney outcomes. Results: Mean baseline age was 65 ± 10 years old. Mean baseline systolic and diastolic BP were 141 ± 17 and 79 ± 12 mm Hg, respectively. More intensive BP control resulted in lower risk of composite cardiovascular outcome (HR 0.79, 95% CI 0.72, 0.87) and all-cause mortality (HR 0.86, 95% CI 0.75, 0.99) without evidence that the BP intervention effects differed by level of baseline diastolic BP (interaction p = 0.76 for cardiovascular composite and 0.85 for all-cause mortality). The mean baseline diastolic BP in the lowest and the upper three quartiles of baseline diastolic BP were 65 ± 6 mm Hg and 84 ± 9 mm Hg, respectively but the effects of the BP interventions on the outcomes were similar in both groups. Furthermore, there was no evidence of interaction of the BP intervention and baseline diastolic BP for kidney outcomes. Conclusions: Within the included diastolic BP range, there was no evidence that baseline diastolic BP modified the beneficial effects of intensive BP lowering.