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Participant selection biases can reduce the generalizability of research findings and lead to misestimates of intervention effectiveness. The authors examined factors associated with study participation and attrition among psychiatric outpatients recruited for the initial phase of a health promotion trial. Medical records were reviewed to obtain HIV-risk and substance abuse data, as well as psychiatric and demographic characteristics of potential participants. Of 895 eligible outpatients, 67% (n = 601) consented to participate, among whom 69% (n = 415) completed all baseline appointments. Compared with nonconsenters, consenters were more likely to be at risk for drug problems and to receive care from clinics serving more impaired patients. Study completion was associated with older age, a psychiatric diagnosis other than adjustment disorder, and a recent sexually transmitted disease diagnosis. These findings suggest that patients who could most benefit from risk reduction interventions are more likely to participate.

Do clinic-referred children and their parents agree on the problems for which treatment is undertaken? The authors asked 381 outpatient-clinic-referred children and their parents to list, independently, the child's target problems. Of the parent-child pairs, 63% failed to agree on even a single problem. When problems were grouped into broad categories (e.g., delinquent, withdrawn), more than a third of the pairs still failed to agree on a single broad problem area. Parent-child agreement was higher for externalizing than for internalizing problem categories (though poor for both). Low parent-child agreement may help explain the poor outcomes often reported for clinic-based child therapy.