explain AMSTAR (A MeaSurement Tool to Assess Systematic Reviews)
AMSTAR (A MeaSurement Tool to Assess Systematic Reviews)
AMSTAR (A MeaSurement Tool to Assess Systematic Reviews) is a widely used critical appraisal tool designed to evaluate the methodological quality of systematic reviews (SRs), including meta-analyses. The original AMSTAR-1 (2007) was updated to AMSTAR-2 (2017) to improve its applicability to both randomized and non-randomized studies of healthcare interventions.
Key Features of AMSTAR-2
AMSTAR-2 consists of 16 items (compared to 11 in AMSTAR-1), assessing different aspects of a systematic review’s methodology. Unlike the original version, AMSTAR-2 does not provide a numerical score but instead evaluates confidence in the review’s results based on critical weaknesses.
Domains Assessed by AMSTAR-2
- Protocol Registration
- Was a review protocol registered before starting the study? (Reduces bias from post-hoc changes).
- Comprehensive Literature Search
- Did the review use multiple databases, grey literature, and manual searches?
- Justification for Study Selection
- Were inclusion/exclusion criteria clearly defined?
- Duplicate Study Selection & Data Extraction
- Were screening and data extraction performed by at least two reviewers independently?
- Risk of Bias (RoB) Assessment in Individual Studies
- Did the review assess RoB (e.g., using Cochrane’s RoB tool, Newcastle-Ottawa Scale)?
- Appropriate Meta-Analysis Methods
- Were statistical methods (e.g., fixed/random effects) justified?
- Consideration of RoB in Synthesis
- Did the review account for RoB when interpreting results?
- Publication Bias Assessment
- Was a test for publication bias conducted (e.g., funnel plot, Egger’s test)?
- Conflict of Interest (COI) Reporting
- Were funding sources and author COIs disclosed?
(Additional items cover heterogeneity, subgroup analysis, and more.)
AMSTAR-2 Rating System
Instead of a numerical score, AMSTAR-2 classifies confidence in the review’s findings as:
| Rating | Description |
|---|---|
| High | No or one non-critical weakness. |
| Moderate | More than one non-critical weakness. |
| Low | One critical flaw (e.g., no RoB assessment). |
| Critically Low | Multiple critical flaws. |
Strengths of AMSTAR-2
✔ Broad Applicability: Works for both randomized and non-randomized reviews.
✔ Detailed Assessment: Covers all key methodological aspects.
✔ No Overemphasis on Scoring: Prevents misleading “quality scores.”
Limitations
✖ Subjective Judgments: Some items require interpretation.
✖ Not a Reporting Guideline: Unlike PRISMA, it assesses methodology, not just reporting.
When to Use AMSTAR-2?
- Evaluating SRs for clinical guidelines.
- Peer-reviewing manuscripts.
- Conducting umbrella reviews (reviews of reviews).
Example AMSTAR-2 Checklist in Practice
If a review:
✅ Registered a protocol (Item 2)
✅ Used multiple databases (Item 4)
❌ Did not assess publication bias (Critical flaw)
→ It would likely be rated “Critically Low” confidence.
Conclusion
AMSTAR-2 is the gold standard for assessing systematic review quality. While it doesn’t generate a score, its structured approach helps identify flaws that could undermine a review’s reliability.
Would you like a downloadable AMSTAR-2 checklist or guidance on applying it to a specific review?
