Cost and cost-effectiveness of computerized vs. in-person motivational interventions in the criminal justice system.

Introduction: Although substance use is common among probationers in the United States, treatment initiation remains an ongoing problem. Among the explanations for low treatment initiation are that probationers are insufficiently motivated to seek treatment, and that probation staff have insufficient training and resources to use evidence-based strategies such as motivational interviewing. A web-based intervention based on motivational enhancement principles may address some of the challenges of initiating treatment but has not been tested to date in probation settings. The current study evaluated the cost-effectiveness of a computerized intervention, Motivational Assessment Program to Initiate Treatment (MAPIT), relative to face-to-face Motivational Interviewing (MI) and supervision as usual (SAU), delivered at the outset of probation.

Methods: The intervention took place in probation departments in two U.S. cities. The baseline sample comprised 316 participants (MAPIT = 104, MI = 103, and SAU = 109), 90% (n = 285) of whom completed the 6-month follow-up. Costs were estimated from study records and time logs kept by interventionists. The effectiveness outcome was self-reported initiation into any treatment (formal or informal) within 2 and 6 months of the baseline interview. The cost-effectiveness analysis involved assessing dominance and computing incremental cost-effectiveness ratios and cost-effectiveness acceptability curves. Implementation costs were used in the base case of the cost-effectiveness analysis, which excludes both a hypothetical license fee to recoup development costs and startup costs. An intent-to-treat approach was taken.

Results: MAPIT cost $79.37 per participant, which was ~$55 lower than the MI cost of $134.27 per participant. Appointment reminders comprised a large proportion of the cost of the MAPIT and MI intervention arms. In the base case, relative to SAU, MAPIT cost $6.70 per percentage point increase in the probability of initiating treatment. If a decision-maker is willing to pay $15 or more to improve the probability of initiating treatment by 1%, estimates suggest she can be 70% confident that MAPIT is good value relative to SAU at the 2-month follow-up and 90% confident that MAPIT is good value at the 6-month follow-up.

Conclusions: Web-based MAPIT may be good value compared to in-person delivered alternatives. This conclusion is qualified because the results are not robust to narrowing the outcome to initiating formal treatment only. Further work should explore ways to improve access to efficacious treatment in probation settings.