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Research Methods & Reporting

AMSTAR 2: a critical appraisal tool for systematic reviews that include randomised or non-randomised studies of healthcare interventions, or both

BMJ 2017; 358 doi: (Published 21 September 2017) Cite this as: BMJ 2017;358:j4008
  1. Beverley J Shea, senior methodologist, clinical investigator, and adjunct professor1 2 3,
  2. Barnaby C Reeves, professor4,
  3. George Wells, director and professor3 5,
  4. Micere Thuku, research associate1 2,
  5. Candyce Hamel, senior clinical research associate1,
  6. Julian Moran, research student6,
  7. David Moher, senior scientist, associate professor, and university research chair1 3,
  8. Peter Tugwell, senior scientist and professor1 2 3 7,
  9. Vivian Welch, clinical investigator and assistant professor2 3,
  10. Elizabeth Kristjansson, professor8,
  11. David A Henry, professor and senior scientist9 10 11
  1. 1Ottawa Hospital Research Institute, Clinical Epidemiology Program, Ottawa, Canada
  2. 2Bruyère Research Institute, Ottawa, Canada
  3. 3School of Epidemiology and Public Health, Faculty of Medicine, University of Ottawa, Ottawa, Canada
  4. 4School of Clinical Sciences, University of Bristol, Bristol, UK
  5. 5University of Ottawa Heart Institute, Ottawa, Canada
  6. 6The Hospital for Sick Children, the Genetics and Genome Biology Program, Toronto, Canada
  7. 7Department of Medicine, The Ottawa Hospital, Ottawa, Canada
  8. 8Centre for Research in Educational and Community Services, School of Psychology, Faculty of Social Sciences, University of Ottawa, Canada
  9. 9Centre for Research in Evidence-Based Practice, Bond University, Gold Coast, Australia;
  10. 10Dalla Lana School of Public Health, University of Toronto, Toronto, Canada
  11. 11Institute for Clinical Evaluative Sciences, Toronto, Canada
  1. Correspondence to: B J Shea bevshea{at}
  • Accepted 4 August 2017

The number of published systematic reviews of studies of healthcare interventions has increased rapidly and these are used extensively for clinical and policy decisions. Systematic reviews are subject to a range of biases and increasingly include non-randomised studies of interventions. It is important that users can distinguish high quality reviews. Many instruments have been designed to evaluate different aspects of reviews, but there are few comprehensive critical appraisal instruments. AMSTAR was developed to evaluate systematic reviews of randomised trials. In this paper, we report on the updating of AMSTAR and its adaptation to enable more detailed assessment of systematic reviews that include randomised or non-randomised studies of healthcare interventions, or both. With moves to base more decisions on real world observational evidence we believe that AMSTAR 2 will assist decision makers in the identification of high quality systematic reviews, including those based on non-randomised studies of healthcare interventions.

Summary points

  • Systematic reviews of studies of healthcare interventions effects often include non-randomised studies

  • AMSTAR is a popular instrument for critically appraising 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, and has an overall rating based on weaknesses in critical domains

  • AMSTAR 2 is not intended to generate an overall score

  • With moves to base more decisions on real world observational evidence, AMSTAR 2 should assist in the identification of high quality systematic reviews

With the rapid increase in biomedical publishing, keeping up with primary research has become almost impossible for healthcare practitioners and policy makers.1 Consequently, healthcare decision …

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