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Am Fam Physician. 2011;84(11):1296-1297

AFP uses the Strength-of-Recommendation Taxonomy (SORT),1 to label key recommendations in clinical review articles. In general, only key recommendations are given a Strength-of-Recommendation grade. Grades are assigned on the basis of the quality and consistency of available evidence. Table 1 shows the three grades recognized.

As the table indicates, the strength-of-recommendation grade depends on the quality and consistency of the evidence for the recommendation. Quality and consistency of evidence are determined as indicated in Table 2 and Table 3.

An alternative way to understand the significance of a strength-of-recommendation grade is through the algorithm generally followed by authors and editors in assigning grades based on a body of evidence (Figure 1). While this algorithm provides a general guideline, authors and editors may adjust the strength of recommendation based on the benefits, harms, and costs of the intervention being recommended.

Strength of recommendationBasis for recommendation
AConsistent, good-quality patient-oriented evidence*
BInconsistent or limited-quality patient-oriented evidence*
CConsensus, disease-oriented evidence,* usual practice, expert opinion, or case series for studies of diagnosis, treatment, prevention, or screening
Study qualityDiagnosisTreatment/prevention/screeningPrognosis
Level 1: good-quality, patient-oriented evidenceValidated clinical decision ruleSR/meta-analysis or RCTs with consistent findingsSR/meta-analysis of good-quality cohort studies
SR/meta-analysis of high-quality studies
High-quality individual RCTProspective cohort study with good follow-up
High-quality diagnostic cohort study*
All-or-none study
Level 2: limited-quality patient-oriented evidenceUnvalidated clinical decision ruleSR/meta-analysis of lower quality clinical trials or of studies with inconsistent findingsSR/meta-analysis of lower quality cohort studies or with inconsistent results
SR/meta-analysis of lower quality studies or studies with inconsistent findings
Lower quality diagnostic cohort study or diagnostic case-control studyLower quality clinical trialRetrospective cohort study or prospective cohort study with poor follow-up
Cohort study
Case-control studyCase-control study
Case series
Level 3: other evidenceConsensus guidelines, extrapolations from bench research, usual practice, opinion, disease-oriented evidence (intermediate or physiologic outcomes only), or case series for studies of diagnosis, treatment, prevention, or screening
ConsistentMost studies found similar or at least coherent conclusions (coherence means that differences are explainable).
If high-quality and up-to-date systematic reviews or meta-analyses exist, they support the recommendation.
InconsistentConsiderable variation among study findings and lack of coherence
If high-quality and up-to-date systematic reviews or meta-analyses exist, they do not find consistent evidence in favor of the recommendation.

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