Table 1.

Strength of Recommendation Taxonomy

Strength of RecommendationDefinition
ABased on consistent and good-quality, patient-oriented evidence*
BBased on inconsistent or limited-quality patient-oriented evidence*
CBased on consensus, usual practice, opinion, or case series
Study QualityDefinitionExamples
Level 1Good-quality, patient-oriented evidence*High-quality RCT
SR or MA of high-quality studies
High-quality prospective cohort study or SR or MA of such studies
Level 2Limited-quality, patient-oriented evidence*Lower-quality clinical trial
Lower-quality cohort study
Retrospective cohort study
SR or MA of lower-quality studies or studies with inconsistent findings
SR or MA of lower-quality cohort studies or studies with inconsistent results
Case-control study
Level 3Other evidenceConsensus guidelines
Expert opinion
Case series
  • Adapted from Ebell et al.22

  • * Patient-oriented evidence measures outcomes that matter to patients, such as morbidity, mortality, symptom improvement, and quality of life. Measures of disease activity or surrogate outcomes may or may not matter to the patient.

  • MA, meta-analysis; RCT, randomized controlled trial; SR, systematic review.