Summary of the Evidence: Behavioral Counseling Interventions in Primary Care to Reduce Risky/Harmful Alcohol Use by Adults

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Table 1. Criteria for Grading the Internal Validity of Individual Studies^a

Randomized, controlled trials:

Adequate randomization, including concealment and equal distribution of potential confounders among groups.

Maintenance of comparable groups (includes attrition, crossovers, adherence, contamination).

Important differential loss to follow-up or overall high loss to follow-up.

Equal, reliable, and valid measurements (includes masking of outcome assessment).

Clear definition of interventions.

Important outcomes considered.

Intention-to-treat analysis.

^aThe Methods Work Group of the U.S. Preventive Services Task Force developed a set of criteria to determine how well individual studies were conducted (internal validity)⁴⁶. The Task Force defined a 3-category rating of "good," "fair," and "poor" based on these criteria. In general, a good study meets all criteria well. A fair study does not meet, or it is not clear that it meets, at least one criterion but has no known important limitation that could invalidate its results. A poor study has important limitations. These specifications are not meant to be rigid rules but rather are intended to be general guidelines; individual exceptions, when explicitly explained and justified, can be made.

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Table 1. Criteria for Grading the Internal Validity of Individual Studiesa

Table 1. Criteria for Grading the Internal Validity of Individual Studies^a