Eighteen studies (n=127,879) were included. Of these, 13 studies (n=105,591) compared beta-blockers with other drugs, and 7 studies (n=27,433) compared beta-blockers with placebo or no antihypertensive treatment; 2 trials had three treatment arms and were included in both analyses.
The risk of stroke was significantly increased by 16% for beta-blockers compared with other antihypertensive drugs (12 studies; RR 1.16, 95% CI: 1.04, 1.3). The risk of stroke was significantly decreased by 19% for beta-blockers compared with placebo (7 studies; RR 0.81, 95% CI: 0.71, 0.93). There was statistically significant heterogeneity between study results for the comparison with other drugs (P=0.02), but not for the comparison with placebo (P=0.23).
The risk of MI was not statistically significantly different for beta-blockers compared with other antihypertensive drugs (12 studies; RR 1.02, 95% CI: 0.93, 1.12) or with placebo (7 studies; RR 0.93, 95% CI: 0.83, 1.05). There was statistically significant heterogeneity between study results for the comparison with other drugs (P=0.04), but not for the comparison with placebo (P=0.85).
In terms of all-cause mortality, the risk of death was not statistically significantly different for beta-blockers compared with other antihypertensive drugs (13 studies; RR 1.03, 95% CI: 0.99, 1.08) or with placebo (7 studies; RR 0.95, 95% CI: 0.86, 1.04). There was no evidence of significant heterogeneity for either comparison (P=0.2 and P=0.13, respectively).
Subgroup analyses.
For the comparison of atenolol with other antihypertensive drugs, the risk of stroke was significantly increased by 26% (6 studies; RR 1.26, 95% CI: 1.15, 1.38); the risk of death was significantly increased by 8% (6 studies; RR 1.08, 95% CI: 1.02, 1.14); and the results for MI were similar to the primary analysis. For the comparisons of atenolol with placebo, and mixed treatments with other drugs, the results for all outcomes were similar to the primary analysis. There were insufficient data to draw conclusions about non-atenolol beta-blockers.