Author Reply: A critical reflection on the grading of the certainty of evidence in umbrella reviews.

I would like to thank Dr. Schlesinger and colleagues for their critical reflection on the grading of the certainty of evidence in umbrella reviews. The classification for meta-analyses is described as Convincing (Class I), Highly suggestive (Class II), Suggestive (Class III) and Weak (Class VI). There may be no formal consensus yet on the use of this classification from recognized professional organizations but they have been repeatedly used from large teams with long lasting expertise in evidence synthesis. [Extracted from the article]