Methodological and Clinical Heterogeneity and Extraction Errors in Meta-Analyses of Catheter Ablation for Atrial Fibrillation in Heart Failure.

Background Meta-analyses are expected to follow a standardized process, and thus, they have become highly formulaic, although there is little evidence that such regimentation yields high-quality results. Methods and Results This article describes the results of a critical examination of 14 published meta-analyses of catheter ablation for atrial fibrillation in heart failure that were based on a nearly identical core set of 4 to 6 primary trials. Methodological issues included (1) the neglect of primary data or the failure to report any primary data; (2) the inaccurate recording of the number of randomized patients; (3) the lack of attention to data missingness or baseline imbalances; (4) the failure to contact investigators of primary trials for additional data; (5) the incorrect extraction of data, the misidentification of events, and the assignment of events to the wrong treatment groups; (6) the calculation of summary estimates based on demonstrably heterogenous data, methods of differing reliability, or unrelated end points; and (7) the development of conclusions based on sparse numbers of events or overly reliant on the results of 1 dominant trial. Conclusions These findings reinforce existing concerns about the methodological validity of meta-analyses and their current status in the hierarchy of medical evidence, and they raise new questions about the process by which meta-analyses undergo peer review by medical journals.