Follow-up contact bias in evaluation of substance abuse treatment programs

This study examined the problem of follow-up contact bias in evaluation of substance abuse treatment programs using administrative data sets. Completed discharges in Iowa were compared to clients contacted 6 months after treatment. The percent of clients reporting no substance use doubled between admission to treatment and follow-up. Unemployment, arrests, and number of days of work or school missed declined. However, clients included in the follow-up sample were significantly different in terms of risk factors for adverse outcomes. The authors conclude that improvements in social functioning 6 months after discharge cannot be generalized to the entire population of clients treated, since those not found have a different combination of risk factors.