Study 1
Chan and colleagues (2005) employed a quasi-experimental design to compare the outcome of drug-involved women who were assigned either to probation case management (PCM) or to standard probation, based on availability of case management services (i.e., as long as slots were available for PCM, eligible participants were assigned to receive PCM). Women were recruited between June 1997 to February 1998 and were eligible to participate in the study if they:
- Were residents of the City and County of San Francisco, Calif.
- Were 18 years of age or older
- Had a substance abuse problem
- Were involved in the criminal justice system (either incarcerated, presentence, or on probation/parole)
Women also had to show a willingness to participate in PCM and substance abuse treatment. Women were excluded if they were currently involved in a drug court or were court-ordered to receive PCM services. This exclusion criterion was necessary to ensure that all eligible women had an equal probability of being assigned to either probation condition, based only on availability of PCM slots; women who were court-ordered were excluded because they had no probability of assignment to standard probation.
Eligible women were placed into the PCM treatment group until all slots were filled (n=65). Women who met eligibility had the choice of entering the study in the comparison condition (n=44) and could receive PCM services on completion of the 12-month follow-up study interview. The treatment group members had an average age of 31.8 years, and were 60 percent African American, 32 percent white, 3 percent Hispanic, and 5 percent “other.” The comparison group members had an average age of 33 years, and were 66 percent African American, 14 percent white, 9 percent Hispanic, 5 percent Asian, and 7 percent “other.” There were no statistically significant differences between the groups on age, education, major drug problem, or history of incarceration. Treatment group members were more often white, more often reported a history of injection drug use, were more likely to be on probation or parole, and had a higher number of prior drug treatment episodes.
The outcome measures of interest included scores on the Addiction Severity Index (ASI), the Beck Depression Inventory (BDI), the Brief Symptom Inventory (BSI), the Social Support Evaluation List, and a questionnaire developed for the study that measured women’s needs. The ASI composite score measured the problem severity in seven areas (medical, employment, legal, alcohol, drug, social, and psychological) over the previous 30 days. The BDI and BSI measured depression and psychiatric symptoms, respectively, in the past 7 days. The Social Support Evaluation List asked questions about self-esteem, emotional support, and social interactions. The women’s need questionnaire was designed to address gender-specific problems, such as child custody issues. Data was collected from study participants at baseline and at 6-month and 12-month follow-up periods.
Change over time in the outcome scores was assessed within and between groups using generalized estimating equation (GEE) and mixed effects regression. The GEE analyses were applied to ASI scores, because outcome measures were dichotomized, and showed the probability of having a high versus a low ASI score. The mixed effects regression analyses were used for the BDI, BSI, and Social Support scores because they were continuous outcome measures. In the analysis of each outcome, time was treated categorically and included main effects for group (PCM versus standard probation); time (baseline, 6-month follow-up, and 12-month follow-up); and group by time interaction.