Treatment retention and follow-up outcomes in the Drug Abuse Treatment Outcome Study (DATOS)

Clients in the national Drug Abuse Treatment Outcome Study reported significant overall improvements in drug use and related measures during a 12-month follow-up period. A quasi-experimental design was used to examine the relationship of treatment duration with outcomes in each of the 3 major modalities represented. Client subsamples with longer retention in long-term residential programs and in outpatient methadone treatment had significantly better outcomes than those with shorter lengths of stay (results were inconclusive for outpatient drug-free programs because of sample limitations). This study used several methodological enhancements and showed general continuity of findings on retention effects from previous national evaluations of treatment effectiveness. It supports the need for more careful study of treatment process in relation to outcomes.