Strength of Recommendations Taxonomy20
| Strength of Recommendations | Definition |
| A | Recommendation based on consistent* and good quality† patient-oriented evidence‡ |
| B | Recommendation based on inconsistent or limited quality patient-oriented evidence |
| C | Recommendation based on consensus, usual practice, opinion, disease-oriented evidence or case series |
For a detailed discussion, see http://www.aafp.org/afp/2004/0201/p548.html.
*Consistency: most studies found similar or at least coherent conclusions, or high-quality and up-to-date systematic reviews exist and support the recommendation.
†Good quality: validated clinical decision rules, meta-analyses of high-quality studies and high-quality individual cohort studies for diagnosis; meta-analyses of RCTs, high-quality individual RCTs and all or none studies for treatment and prevention; and meta-analyses of good quality cohort studies and individual cohort studies with good follow-up for prognosis.
‡Patient-oriented evidence: outcomes that matter to patients, such as morbidity, mortality, symptom improvement, cost reduction and quality of life.
RCT, randomised controlled trial.