Predicting readmission to substance abuse treatment using state information systems. The impact of client and treatment characteristics.

The purpose of this study was to use administrative records of admissions to substance abuse treatment to construct episodes of care for publicly funded clients in Washington State, and then to analyze readmissions to treatment after an index episode. The study population was those clients who began and ended an index episode in 1995 (N = 10,284). The population was divided into two groups, which were separately analyzed based on programs run by the Washington State Division of Alcohol and Substance Abuse (DASA) [Alcohol and Drug Abuse Treatment and Support Act (ADATSA) and Non-ADATSA, named for legislation defining these programs]. Clients in each program were followed for 13 months, and proportional hazards regression was used to estimate the relationship between our treatment measures and readmission, controlling for several covariates. We compared clients based on several aspects of treatment, but our primary interest was in comparing clients that completed the index episode with those that did not complete it. For both ADATSA and Non-ADATSA clients, those completing their episode of treatment had significantly lower risks for readmission. Females and those arrested in the year prior to treatment had increased risks of readmission, while males and those receiving a combination of inpatient and outpatient treatments had lower risks of readmission. The discussion concludes with suggestions for improving statewide systems of care.