Thirteen RCTs (n = 12,491) were included in the review. All trials were considered to be high quality. Follow-up time ranged from six months to two years.
Antibiotics did not significantly differ from placebo in the prevention of composite outcome of cardiac events (death, nonfatal MI, angina or unplanned revascularisation) (RR 0.96, 95% CI: 0.89, 1.05). Similar results were found for individual outcomes of mortality and MI or unstable angina. Subgroup analysis revealed no effect of antibiotic used or whether anti-Chlamydia immunoglobulin titres were an inclusion criterion. There was a trend toward significance for patients with unstable coronary artery disease (RR 0.92, 95% CI: 0.84, 1.01), however, the RD was 0.016 (95%CI: -0.003, 0.034), indicating a range from a NNT of 29 to a number need to harm (NNH) of 333. A sensitivity analysis using a fixed-effect model produced similar results.
Funnel plots suggested the presence of publication bias.