The cost-effectiveness of financial incentives to achieve heroin abstinence in individuals with heroin use disorder starting new treatment episodes: A cluster randomised controlled trial-based economic evaluation

OBJECTIVES: Cost-effectiveness analysis of two 12-week contingency management (CM) schedules targeting heroin-abstinence or attendance at weekly keyworker appointments for opioid agonist treatment (OAT), compared to treatment as usual (TAU). METHODS: Cost-effectiveness analysis was conducted alongside a cluster randomised trial of 552 patients from 34 clusters (drug treatment clinics) randomly allocated 1:1:1 to OAT plus weekly keyworker appointments with either: i) CM targeted at heroin-abstinence (CM Abstinence); ii) CM targeted at on-time attendance at weekly appointments (CM Attendance); or, iii) no CM (TAU). The primary cost-effectiveness analysis at 24 weeks post-randomisation took a societal cost perspective with effects measured in heroin-negative urine samples. RESULTS: At 24-weeks, mean differences in weekly heroin-negative urine results compared with TAU were 0.252 (95%CI -0.397 to 0.901) for CM Abstinence and 0.089 (95%CI -0.223 to 0.402) for CM Attendance. Mean differences in costs were £2562 (95%CI £32 to £5092) for CM Abstinence and £317 (95%CI -£882 to £1518) for CM Attendance. Incremental cost-effectiveness ratios were £10,167 per additional heroin-free urine for CM Abstinence and £3,562 for CM Attendance with low probabilities of cost-effectiveness of 3.5% and 36%, respectively. Results were sensitive to timing of follow-up for CM Attendance, which dominated TAU (better outcomes, lower costs) at 12-weeks, with an 88.4% probability of being cost-effective. Probability of cost-effectiveness remained low for CM Abstinence (8.6%). CONCLUSIONS: Financial incentives targeted toward heroin-abstinence and treatment-attendance were not cost-effective over the 24-week follow-up. However, CM Attendance was cost-effective over the treatment period (12-weeks), when participants were receiving keyworker appointments and incentives