Interaction effects of treatment setting and client characteristics on retention and completion.

Client-treatment matching assumes treatment outcome will be improved if characteristics of clients are matched to specific elements of treatment. Few empirical studies, however, have examined matching across different types of treatment settings. The present research examined differences in demographics and substance-related problems in populations admitted to three substance abuse treatment settings--outpatient (n = 1132), intensive outpatient (n = 1190), and residential (n = 149)--and tested whether interactions between client characteristics and type of setting predicted rates of 30-day retention and treatment completion. In addition, three specific hypotheses based on prior theoretical and empirical investigations were tested. Client characteristics included demographic information (e.g., sex, age, race) and Addiction Severity Index (ASI) composite scores. Client-setting interactions were found for both retention and completion. All three hypotheses received at least partial support. Implications for client assignment and future research are discussed.