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Evidence Based Medicine

What is Evidence Grading?

Evidence grading is a systematic method for assessing and rating the quality of evidence that is produced from a research study, clinical guideline, a systematic review, or expert opinion.

GRADE Approach

Reporting Evidence

Always consider existing standards for reporting the findings of scientific and medical research in a way that will limit bias and aid in evidence based critical appraisal. We have listed a few below. For more, see the the Equator Network's reporting guidelines page.

Tools for Evidence Grading

  • CASP Checklists
  • This set of eight critical appraisal tools are designed to be used when reading research, these include tools for Systematic Reviews, Randomised Controlled Trials, Cohort Studies, Case Control Studies, Economic Evaluations, Diagnostic Studies, Qualitative studies and Clinical Prediction Rule.

  • Cochrane Collaboration's Risk of Bias Tool
  • This set of eight critical appraisal tools are designed to be used when reading research, these include tools for Systematic Reviews, Randomised Controlled Trials, Cohort Studies, Case Control Studies, Economic Evaluations, Diagnostic Studies, Qualitative studies and Clinical Prediction Rule.

  • The JADAD scale for reporting Randomized Controlled Trials
  • Jadad, A. R., Moore, R. A., Carroll, D., Jenkinson, C., Reynolds, D. J., Gavaghan, D. J., & McQuay, H. J. (1996). Assessing the quality of reports of randomized clinical trials: is blinding necessary? Controlled clinical trials, 17(1), 1–12. https://doi.org/10.1016/0197-2456(95)00134-4

  • GRADE Working Group
  • The Grading of Recommendations Assessment, Development and Evaluation (short GRADE) working group began in the year 2000 as an informal collaboration of people with an interest in addressing the shortcomings of grading systems in health care. The working group has developed a common, sensible and transparent approach to grading quality (or certainty) of evidence and strength of recommendations.

  • Newcastle-Ottawa Scale
  • The Newcastle-Ottawa Scale (NOS) is an ongoing collaboration between the Universities of Newcastle, Australia and Ottawa, Canada. It was developed to assess the quality of nonrandomised studies with its design, content and ease of use directed to the task of incorporating the quality assessments in the interpretation of meta-analytic results.

  • OHAT Risk of Bias Rating Tool
  • The OHAT Risk of Bias Rating Tool can be used for human and animal studies.

  • Oxford Centre for Evidence-based Medicine Levels of Evidence
  • The CEBM Levels of Evidence framework sets out one approach to systematizing this grading process for different question types.

  • SYRCLE's Risk of Bias Tool
  • This tool is based on the Cochrane RoB tool and has been adjusted for aspects of bias that play a specific role in animal intervention studies.

  • U.S. Preventive Services Task Force
  • The U.S. Preventive Services Task Force (USPSTF) assigns one of five letter grades (A, B, C, D, or I). The USPSTF changed its grade definitions based on a change in methods in May 2007 and again in July 2012, when it updated the definition of and suggestions for practice for the grade C recommendation.