What evidence do we have about the effectiveness of antihypertensive drugs in preventing cardiovascular diseases?
Studies to answer this question must be randomized, controlled, and double-blind to prevent bias and must be large and of sufficient duration. In 1990 a meta-analysis of the 14 trials which met defined criteria was published.(1) This analysis (mean age 52 years, 53% male), demonstrated that a 5-6 mm Hg decrease in diastolic blood pressure produced a 14% reduction in coronary heart disease, and a 42% reduction in cerebrovascular accidents over a 5 year follow-up period. Since 1990, five additional trials have been published. These trials have confirmed and strengthened the original meta-analysis, and demonstrated a greater relative and absolute risk reduction, particularly for coronary artery disease in the elderly (2) plus the benefit of treating isolated systolic hypertension.(3) Most of the patients in these trials received thiazide diuretics as the only drug or as a component of the treatment. We therefore have compelling evidence of the effectiveness of this class of drugs in reduc
