CriteriaGood RatingFair RatingPoor Rating
Initial assembly of comparable groups (adequate randomization, including first concealment and whether potential confounders were distributed equally among groups)Met all criteria: comparable groups were assembled initially and maintained throughout the study (overall followup at least 90% and difference in followup between groups no greater than 10 percentage points); reliable and valid measurement instruments were used and applied equally to the groups; interventions were spelled out clearly; all important outcomes were considered; appropriate attention to confounders in analysis; and participants were analyzed in the groups to which they were randomized. Conservative data substitution methods were used, such as baseline observation carried forward or multiple imputation, where data substitution is used.Studies were graded “fair” if any or all of the following problems occurred, without the fatal flaws noted in the “poor” category: generally comparable groups were assembled initially but some question remained whether some (although not major) differences occurred with followup; measurement instruments were acceptable (although not the best) and generally applied equally; some but not all important outcomes were considered; and some but not all potential confounders were accounted for. Participants were analyzed in the groups to which they were randomized.Studies were graded “poor” if any of the following fatal flaws existed: groups assembled initially were not close to being comparable or maintained throughout the study; unreliable or invalid measurement instruments were used or not applied at all equally among groups (including not masking outcome assessment); key confounders were given little or no attention; or participants were analyzed according to intervention received, rather than an intention-to-treat approach.
Maintenance of comparable groups (includes attrition, cross-overs, adherence, contamination)
Important differential loss to followup or overall high loss to followup
Equal, reliable, and valid measurements (includes masking of outcome assessment)
Clear definition of interventions
All important outcomes considered
Analysis (analyzed according to randomization status [intention-to-treat] rather than intervention received)

From: Appendix F, U.S. Preventive Services Task Force Quality Criteria and Ratings

Cover of Primary Care Relevant Interventions for Tobacco Use Prevention and Cessation in Children and Adolescents
Primary Care Relevant Interventions for Tobacco Use Prevention and Cessation in Children and Adolescents: A Systematic Evidence Review for the U.S. Preventive Services Task Force [Internet].
Evidence Syntheses, No. 97.
Patnode CD, O'Connor E, Whitlock EP, et al.

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