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. Author manuscript; available in PMC: 2016 Apr 20.
Published in final edited form as: J Acquir Immune Defic Syndr. 2015 Apr 15;68(Suppl 3):S253–S256. doi: 10.1097/QAI.0000000000000495

Table 2.

Criteria for rating the quality of evidence* for individual studies

Level of evidence Description
1=STRONG Systematic review/meta-analysis of randomized controlled trials (RCTs) with consistent findings; high-quality individual RCT
2=MEDIUM Systematic review/meta-analysis of lower-quality clinical trials or of studies with inconsistent findings; lower-quality clinical trial; cohort study; case-control study
3=WEAK Consensus guidelines; usual practice; expert opinion; case series
*

Criteria for rating the quality of evidence for each study were adapted from the U.S. Preventive Services Task Force Procedure Manual7. For purposes of these reviews, ratings could be modified by other factors, including the number of study participants and an assessment of the internal and external validity of the study data.