Methods: A meta-analysis was performed according to PRISMA and MOOSE guidelines for reporting of systematic reviews of observational studies. PubMed, Embase, and Cochrane central were searched and two authors independently screened studies for eligibility. The quality of studies was assessed with the Newcastle Ottawa scale. The primary outcome of interest was all-cause mortality, cardiovascular (CV) mortality and major adverse cardiovascular events (MACE) in diabetic patients with and without BB therapy. A generic inverse variance model was used to pool the odds ratio or hazards ratio from included studies to calculate the overall effect estimate. The significance threshold was set at p-value <0.05. Heterogeneity was assessed by I2.
Results: Four non-randomized studies with 9,515 participants were selected for the analyses. Four studies were post-hoc analyses of randomised controlled trials, and 1 article was an analysis of a nationally representative survey. In a fixed effects model, BB therapy in diabetic patients with stable CHD was found to be associated with increased risk of CV mortality, and MACE (27%, and 32% respectively; p-value <0.05) and was not associated with a reduction in all-cause mortality (HR 1.12; 95% CI 0.94-1.33; p-value =0.22).
Conclusion: BB therapy in diabetic patients with stable CHD appears to be linked to higher mortality. Large randomised trials are needed in this population to confirm these findings.