Effects of blood pressure reduction in mild hypertension: a systematic review and meta-analysis

BACKGROUND: Effects of blood pressure reduction in persons with grade 1 hypertension are unclear. PURPOSE: To investigate whether pharmacologic blood pressure reduction prevents cardiovascular events and deaths in persons with grade 1 hypertension. DATA SOURCES: Trials included in the BPLTTC (Blood Pressure Lowering Treatment Trialists' Collaboration) and trials identified from a previous review and electronic database searches. STUDY SELECTION: Patients without cardiovascular disease with blood pressures in the grade 1 hypertension range (140 to 159/90 to 99 mm Hg) who were randomly assigned to an active (antihypertensive drug or more intensive regimen) or control (placebo or less intensive regimen) blood pressure-lowering regimen. DATA EXTRACTION: Individual-patient data from BPLTTC trials and aggregate data from other trials were extracted. Risk of bias was assessed for all trials. DATA SYNTHESIS: Individual-patient data involved 10 comparisons from trials where most patients had diabetes, and aggregate data involved 3 comparisons from trials of patients without diabetes. The average blood pressure reduction was about 3.6/2.4 mm Hg. Over 5 years, odds ratios were 0.86 (95% CI, 0.74 to 1.01) for total cardiovascular events, 0.72 (CI, 0.55 to 0.94) for strokes, 0.91 (CI, 0.74 to 1.12) for coronary events, 0.80 (CI, 0.57 to 1.12) for heart failure, 0.75 (CI, 0.57 to 0.98) for cardiovascular deaths, and 0.78 (CI, 0.67 to 0.92) for total deaths. Results were similar in secondary analyses. Withdrawal from treatment due to adverse effects was more common in the active groups. LIMITATION: Blood pressure reductions and numbers of events were small. CONCLUSION: Blood pressure-lowering therapy is likely to prevent stroke and death in patients with uncomplicated grade 1 hypertension. PRIMARY FUNDING SOURCE: Swedish Heart-Lung Foundation, Swedish Research Council, Australian Research Council, and National Health and Medical Research Council of Australia