Systematic review of the effectiveness of specific anti-hypertensive drug therapy

Article type
Authors
Wright JM, Lee CH, Adams SP, Chambers GK
Abstract
Introduction: Hypertension is a common condition associated with an increased risk of cardiovascular disease and mortality. Anti-hypertensive treatment is important because of evidence that it is effective in reducing this increased morbidity and mortality. Data on the effectiveness of different classes and doses of drugs would be helpful to physicians to make selection of anti-hypertensive therapy more evidence-based.

Objective: To assess the comparative effectiveness of antihypertensive therapy based on (1) low-dose thiazides, high-dose thiazides and beta-blockers vs. placebo and (2) thiazides vs. beta-blockers, in preventing cardiovascular morbidity and mortality.

Methods: All published randomized controlled trials (RCT) examining either the effectiveness of individual drugs vs. placebo or the relative effectiveness of thiazide and beta-blocker were identified through MEDLINE search and reference lists of articles. The identified trials were reviewed independently by 3 reviewers against a pre-established set of criteria. Only the results from the trials meeting the criteria were included in the meta-analysis and all the comparisons were made in terms of four outcomes: total cardiovascular events, total mortality, total stroke events and total CHD events.

Results: In the placebo RCT of individual treatment low-dose thiazide based treatment was found to statistically lower total mortality ( odds ratio, 0.80; 99% CI. 0.68 to 0.95; p less than 0.01), and the risk of total CHD (odds ratio 0.70; CI, 0.57 to 0.86) while high-dose thiazide based treatment did not. Beta-blocker based treatments did not show statistically significant risk reduction in any of the endpoint categories. In the comparison between thiazide and beta-blocker based treatments, there is a trend for thiazides to be better for all outcomes, but none was statistically significant.

Discussion: In placebo controlled trials, low-dose thiazides appear to reduce adverse cardiac outcomes better than high-dose thiazides or beta-blockers. In thiazide vs. beta-blocker RCT's, there a trend towards a better outcome with thiazide.