Umbrella Reviews: What, Why, and How

The number of systematic reviews or secondary-level evidence is proliferating, even more than the increase in primary studies. Controversial topics, biased findings, and inconclusive evidence have led policymakers and researchers toward the tertiary level of evidence, that is, “umbrella review”. Despite the fact that umbrella reviews are a relatively new methodology, their numbers have steeply risen in the last decades, suggesting a growing interest and need in this line of research. Several guidelines have been published on conducting umbrella reviews; however, the existing incongruities leave researchers confused about the best way of practice. In the current study, we aimed to clarify the necessity, circumstances, challenges, and pitfalls of umbrella reviews. Lastly, step-by-step guidelines are proposed for the procedure of conducting and drafting the report of an umbrella review. We hope that the present text and the provided practical instructions draw the attention of the Iranian academic community to umbrella reviews s.