Levels of Evidence

Select an evidence rating scale to display detailed information.

• Centre for Evidence-Based Medicine, Oxford (1a-5)
• SORT: Strength-of-Recommendation Taxonomy (A,B,C)
• GRADE: Grading of Recommendations Assessment, Development and Evaluation (A,B,C,D)
• Practice Guidelines rading scales (various)

Strength-of-Recommendation Taxonomy (SORT)

Code	Definition
A	Consistent, good-quality patient-oriented evidence *
B	Inconsistent or limited-quality patient-oriented evidence *
C	Consensus, disease-oriented evidence *, usual practice, expert opinion, or case series for studies of diagnosis, treatment, prevention, or screening

* Patient-oriented evidence measures outcomes that matter to patients: morbidity, mortality, symptom improvement, cost reduction, and quality of life. Disease-oriented evidence measures immediate, physiologic, or surrogate end points that may or may not reflect improvements in patient outcomes (e.g. blood pressure, blood chemistry, physiologic function, pathologic findings).