Our results for all reviews (combined MMR of 1,08) are very similar to the results reported by reviews conducted in a similar manner. Therefore, we got similar conclusions; on average, there is very little evidence indicating significant differences in the estimate of effect between observational studies and RCTs, regardless of specific observational study design, heterogeneity, or inclusion studies of pharmacological interventions. Factors other than the study design itself should be considered when exploring the reasons for disagreement between the results of RCTs and observational studies. Our results underscore that it is important for review authors to consider not only study design, but also level of heterogeneity in meta-analyzes of RCTs or observational studies. A better understanding of how these factors influence the effects of studies could lead to representative estimates of actual effectiveness.
(Translated) https://www.cochranelibrary.com/cdsr/do ... anguage=fr