• Systematic reviews of studies of healthcare interventions effects often include non-randomised studies
  
  
• AMSTAR is a popular instrument for critically appraising ONLY systematic reviews of randomised controlled clinical trials
  
  
• AMSTAR underwent further development to enable appraisal of systematic reviews of randomised and non-randomised studies of healthcare interventions

• The revised instrument (AMSTAR 2) retains 10 of the original domains
  
  
• Has 16 items in total (compared with 11 in the original)
  
  
• Has simpler response categories than the original AMSTAR
  
  
• Includes a more comprehensive user guide
  
  
• The overall rating is based on weaknesses in critical domains.
  
  
• AMSTAR 2 is not intended to generate an overall score.
  

Read the full article

High - Zero or one non-critical weakness: The systematic review provides an accurate and comprehensive summary of the results of the available studies that address the question of interest

Moderate - More than one non-critical weakness*: The systematic review has more than one weakness, but no critical flaws. It may provide an accurate summary of the results of the available studies that were included in the review.

Low - One critical flaw with or without non-critical weaknesses: The review has a critical flaw and may not provide an accurate and comprehensive summary of the available studies that address the question of interest.

Critically low - More than one critical flaw with or without non-critical weaknesses: The review has more than one critical flaw and should not be relied on to provide an accurate and comprehensive summary of the available studies.

*Note: Multiple non-critical weaknesses may diminish confidence in the review and it may be appropriate to move the overall appraisal down from moderate to low confidence

Download AMSTAR 2 here and it's guidance document here