Levels of Evidence and Study Design: Rating Systems

Oxford University’s Centre for Evidence-Based Medicine (CEBM) has created critical appraisal worksheets to help appraise clinical evidence by its applicability, importance and reliability. There are separate worksheets for systematic reviews, prognosis, diagnosis, random controlled trials and qualitative studies.

The Grading of Recommendations Assessment, Development and Evaluation (GRADE) working group created the GRADE approach to rating the quality of evidence and strength of recommendations. This group first started collaborating in 2000 with the goal of addressing shortcomings found in grading systems in health care.

The journal, American Family Physician, provides information on the Strength of Recommendation Taxonomy (SORT) as a section of their Evidence-based Medicine Toolkit. This rating system, used by many family medicine journals, helps to evaluate the strength of recommendations based on a body of evidence.

The U.S. Preventive Services Task Force (USPSTF) is an independent, volunteer panel of experts in prevention and evidence-based medicine. Members come from the fields of preventive medicine and primary care. The Task Force uses a letter grade to rank peer-reviewed evidence with the goal of helping primary care physicians and patients to appraise preventive services.