Cost-effectiveness analysis of two 12-week contingency management (CM) schedules targeting heroin abstinence or attendance at weekly keyworker appointments for opioid agonist treatment compared with treatment as usual (TAU).
A cost-effectiveness analysis was conducted alongside a cluster randomized trial of 552 patients from 34 clusters (drug treatment clinics) randomly allocated 1:1:1 to opioid agonist treatment plus weekly keyworker appointments with (1) CM targeted at heroin abstinence (CM abstinence), (2) CM targeted at on-time attendance at weekly appointments (CM attendance), or (3) no CM (TAU). The primary cost-effectiveness analysis at 24 weeks after randomization took a societal cost perspective with effects measured in heroin-negative urine samples.
At 24 weeks, mean differences in weekly heroin-negative urine results compared with TAU were 0.252 (95% confidence interval [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-£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 £3562 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%).
Financial incentives targeted toward heroin abstinence and treatment attendance were not cost-effective over the 24-week follow-up. Nevertheless, CM attendance was cost-effective over the treatment period (12 weeks), when participants were receiving keyworker appointments and incentives.