New meta-analysis of treatment trials of hypertension: improving the estimate of therapeutic benefit.

The objectives of this sub group meta-analysis on the treatment of hypertension was to: (1) high-light specific results of well-designed trials; (2) group trials according to their specific clinical context; (3) express results of the meta-analysis in absolute reduction terms; and (4) estimate the bias of withdrawal because of blood pressure increase. This meta-analysis is based on summarised published results from randomised controlled trials, comparing a drug treatment versus placebo or no treatment, with morbi-mortality as the principle outcome. The following data were analysed: (1) total mortality; (2) cardiovascular mortality; (3) stroke; (4) major coronary events; and (5) congestive heart failure. The treatment significantly reduced the incidence of all outcomes in trials involving older patients, avoiding up to nine strokes (OR = 0.66, 95% Cl: 0.56-0.77) and four major coronary events (OR = 0.79, 95% Cl: 0.68-0.92) every 1000 patient-years when the bias of withdrawal was taken into account. The only outcome significantly influenced by treatment in younger patients with mild-to-moderate hypertension was stroke, with one stroke avoided every 1000 patient-years (OR = 0.51, 95% Cl: 0.39-0.66). There was insufficient statistical power in the trials which enrolled patients with non-moderate hypertension to reach clinical significance, except for the reduction in the incidence of congestive heart failure. However, the results indicated a trend towards greater absolute benefit under treatment. Trials enrolling patients with post-stroke hypertension also had insufficient power, but suggested benefit by the reduction of the incidence of stroke recurrence and congestive heart failure under treatment. In conclusion, the most constant treatment benefit concerned stroke, although the absolute reduction was very modest in younger patients with mild-to-moderate hypertension. Only the results from trials in older patients showed a significant reduction of major coronary events. Such results need further analyses, ideally based on individual patient data.