The relationship between eligibility criteria for participation in alcohol brief intervention trials and other alcohol and health-related variables

In clinical trials of brief interventions for alcohol use, individuals typically are defined as eligible for the research through meeting quantity-frequency (QF) of alcohol consumption criteria, alcohol-related problems criteria, or both. The purpose of this study was to evaluate preintervention and posttreatment differences among three groups of research participants eligible for participation in a brief intervention clinical trial by meeting the AUDIT total score criterion only, the QF criterion only, or both. The participants were 301 men and women 21 years of age or older who presented for medical treatment at one of twelve primary care clinics and mere screened for participation in the clinical trial. Participants completed an assessment protocol at preintervention and 1, 3, 6, 9, and 12 months postintervention. The analyses showed statistical differences among the three subgroups on three outcome dimensions of alcohol consumption, related consequences and behaviors, and medical complications; for both con sumption and complications, the AUDIT + QF participants showed greater severity than participants in either of the other two groups. For consequences, AUDIT + QF participants scored higher than the QF participants on one variable constituting this dimension. The overall subgroup differences were maintained at six months in the consumption and consequences data. The implications of these findings for sensitivity of brief intervention trial design, the discovery of patient moderators of intervention effectiveness, and clinical practice are discussed.