Testing mechanisms of action for intensive case management.

Aim: This study identified factors that predict, mediate or moderate the effects of intensive case management (ICM) on longer-term drug abstinence outcomes in women on welfare.

Design: In a parent study women were assigned randomly to usual care (UC) or intensive case management (ICM). Treatment was provided for 12 weeks and follow-up continued for 15 months after study intake. A set of hypothesized mediators was assessed at month 3 and a rigorous four-step mediational model was tested using outcomes in months 4-15.

Participants: Participants were 302 drug-dependent women applying and eligible for federal welfare and not currently in drug abuse treatment. Interventions ICM provided intensive treatment engagement including voucher incentives for treatment attendance and case management services; UC provided primarily referral to community treatment programs.

Measurement: Substance use outcomes were assessed using the time-line follow-back interview and confirmed using biological and collateral measures.

Findings: Participants in ICM had more case manager contacts, better treatment engagement and more self-help attendance than did those in UC. Each of these variables predicted, and was shown to be a mediator of outcome, but case management contact was an especially robust mediator. Further, ICM effects were strongest for those who attended treatment least. Contrary to prediction, greater psychopathology and environmental stressors did not predict worse outcomes.

Conclusions: Findings suggest that case management is an active intervention that may both facilitate and substitute for formal drug abuse treatment.