What is the difference between AMSTAR and AMSTAR 2?

AMSTAR 2 replaced the original AMSTAR tool in 2017. Key differences include the addition of items for non-randomized studies, revised response options that go beyond simple yes/no, the introduction of critical versus non-critical domain classifications, and a structured approach to generating an overall confidence rating. AMSTAR 2 is not a revised scoring tool but rather a critical appraisal instrument that assesses the impact of methodological weaknesses on the reliability of results.

Can AMSTAR 2 be used for scoping reviews?

No, AMSTAR 2 was specifically designed for systematic reviews of intervention studies (both randomized and non-randomized). It is not appropriate for scoping reviews, qualitative systematic reviews, or diagnostic test accuracy reviews. For scoping reviews, the JBI critical appraisal checklist or the PRISMA-ScR checklist are more appropriate tools.

How do you calculate an AMSTAR 2 score?

AMSTAR 2 does not produce a numerical score. Instead, it generates an overall confidence rating of high, moderate, low, or critically low based on the pattern of weaknesses identified. If no critical flaws and up to one non-critical weakness are found, confidence is rated high. One critical flaw drops the rating to low. Two or more critical flaws result in critically low confidence.

Who should use AMSTAR 2?

AMSTAR 2 is used by researchers conducting umbrella reviews to assess the quality of included systematic reviews, by guideline development groups to evaluate the reliability of systematic reviews informing clinical recommendations, by peer reviewers assessing submitted systematic review manuscripts, and by clinicians and policymakers evaluating whether a systematic review's findings are trustworthy enough to inform decisions.

AMSTAR 2 Checklist: Assess Systematic Review Quality

AMSTAR 2 (A MeaSurement Tool to Assess systematic Reviews, version 2) is the standard critical appraisal instrument for evaluating the methodological quality of systematic reviews. Published in 2017 by Shea and colleagues, AMSTAR 2 contains 16 items organized into critical and non-critical domains that assess whether a systematic review was conducted with sufficient rigor to produce reliable results.

AMSTAR 2 is used in umbrella reviews to assess included systematic reviews, by clinical guideline development groups to evaluate evidence quality, by peer reviewers assessing manuscripts, and by researchers and clinicians who need to determine whether a systematic review's conclusions can be trusted. Understanding how to apply and interpret AMSTAR 2 is essential for anyone who reads, conducts, or commissions systematic reviews.

The 16 AMSTAR 2 Items

Sixteen AMSTAR 2 items in a 4 by 4 grid, with the seven critical items (2, 4, 7, 9, 11, 13, 15) marked in red borders — AMSTAR 2: sixteen items, seven of them critical for the overall verdict. Source: Shea et al., 2017, BMJ.

AMSTAR 2 evaluates systematic reviews across 16 methodological domains. Seven are designated as critical domains (marked with an asterisk below) that can independently lower the overall confidence rating.

#	Item	Critical?
1	Did the research questions and inclusion criteria include PICO components?	No
2	Was the review protocol registered before the review began, and were significant deviations reported?*	Yes
3	Did the review authors explain their selection of study designs for inclusion?	No
4	Did the review authors use a comprehensive literature search strategy?*	Yes
5	Was study selection performed in duplicate?	No
6	Was data extraction performed in duplicate?	No
7	Did the review authors provide a list of excluded studies and justify the exclusions?*	Yes
8	Did the review describe the included studies in adequate detail?	No
9	Did the review use a satisfactory technique to assess risk of bias in individual studies?*	Yes
10	Did the review report funding sources for included studies?	No
11	If meta-analysis was performed, did the review use appropriate methods for statistical combination?*	Yes
12	If meta-analysis was performed, did the review assess the potential impact of risk of bias on the results?*	Yes
13	Did the review account for risk of bias when interpreting and discussing results?*	Yes
14	Did the review provide a satisfactory explanation for any heterogeneity observed?	No
15	If quantitative synthesis was performed, did the review carry out adequate investigation of publication bias and discuss its likely impact?*	Yes
16	Did the review authors report any potential sources of conflict of interest, including funding?	No

The 7 Critical Domains Explained

The critical domains represent methodological elements whose absence or inadequacy is most likely to affect the validity of the review's conclusions.

Item 2: Protocol Registration

The review should have a registered protocol (on PROSPERO or equivalent) published before the review began. The protocol should follow PRISMA-P and any deviations from the protocol should be reported and justified. Protocol registration prevents selective reporting and post-hoc methodological changes.

Item 4: Comprehensive Search Strategy

The search should cover at least two relevant databases with a documented Boolean search strategy. The search should include reference list checking, expert consultation, and grey literature searching where appropriate. See our search strategy guide for what constitutes a comprehensive search.

Item 7: List of Excluded Studies With Justifications

The review should provide a list of studies excluded at the full-text screening stage with specific reasons for each exclusion, following the eligibility criteria defined in the protocol. This enables readers to assess whether relevant studies were inappropriately excluded.

Rating	Criteria
High	No critical flaws and no more than one non-critical weakness
Moderate	No critical flaws but more than one non-critical weakness
Low	One critical flaw with or without non-critical weaknesses
Critically Low	More than one critical flaw with or without non-critical weaknesses

AMSTAR 2 Checklist: How to Assess Systematic Review Quality

Key Takeaways

The 16 AMSTAR 2 Items

The 7 Critical Domains Explained

Item 2: Protocol Registration

Item 4: Comprehensive Search Strategy

Item 7: List of Excluded Studies With Justifications

Item 9: Risk of Bias Assessment

Frequently Asked Questions

Related Articles

Quality Assessment Takes Expertise. Our Team Does It Daily.

Dr. Sarah Mitchell

Quality Assessment Takes Expertise. Our Team Does It Daily.

Item 11: Appropriate Meta-Analytical Methods

Item 12: Impact of Risk of Bias on Meta-Analysis Results

Item 13: Risk of Bias in Interpretation

How to Rate Overall Confidence

Applying AMSTAR 2: Practical Tips

Calibrate Before Starting

Use the Detailed Guidance

Document Your Assessments

Present Results in Tables

Limitations of AMSTAR 2

Related Articles