AMSTAR 2

AMSTAR 2 is a checklist for judging how well a systematic review was conducted. The name stands for A MeaSurement Tool to Assess systematic Reviews, in its second version, published in 2017. It has 16 items covering the protocol, the literature search, study selection and data extraction in duplicate, assessment of risk of bias in the included studies, the methods used for pooling, and the handling of funding and conflicts of interest. Seven of the 16 are marked critical: registration of a protocol before the review began, adequacy of the search, justification of excluded studies, appropriate risk of bias assessment, suitable statistical methods, consideration of risk of bias when interpreting results, and assessment of publication bias. The instrument does not produce a score. It produces one of four overall confidence ratings: high, moderate, low, or critically low. One critical flaw drops a review to low, more than one to critically low. Reporting an AMSTAR score out of 16 is a common misuse, because the items are not equally weighted and the tool was never designed to be summed. The difference from GRADE matters: this tool appraises the conduct of the review, while GRADE appraises the certainty of the underlying evidence. A flawless review of weak trials still yields low certainty. The two are used together.

Last reviewed: August 25, 2026

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