Objective: We studied the influence of the methodologic quality of individual trials on the outcome of a landmark meta-analysis on thrombolytic therapy in acute myocardial infarction. From each study we extracted the number of patients in both groups who died in hospital or during follow-up. Methodologic quality was assessed using the Delphi list. We first recalculated pooled odds ratios (ORs) and 95% confidence intervals (CIs), on the studies found and compared them with the original results of Yusuf et al. Next we incorporated the results of quality assessment in five different ways in the calculation of the pooled ORs: a) component analysis; b) visual plot; c) quality score as a threshold score; d) quality score as a weighting factor; and e) cumulative pooling.

Results and Conclusion: No correlation between quality scores and ORs was found. Studies with a proper description of the different quality components provided an estimate close to the true treatment effect. No major differences were found between the results of the five different methods of incorporating the quality scores into the final conclusion.