Adding the Coping Power Programme to parent management training: the cost-effectiveness of stacking interventions for children with disruptive behaviour disorders.

Parent management training (PMT) programmes and child cognitive behavioural therapy are recommended approaches for treatment of oppositional defiant disorder in children, and combining these may be effective. However, little is known regarding the economic efficiency of this additive effect. A within-trial cost-effectiveness analysis was carried out in Sweden including 120 children aged 8-12 who screened positive for disruptive behaviour disorders, within a psychiatric care setting, and their parents. They were randomly assigned to either the Swedish group-based PMT Comet, or to an enhanced version, where an additional child component was provided, the Coping Power Programme (CPP). Child behaviour problems as well as healthcare and educational resource use were measured at baseline, post-test and at two-year follow-up. A net benefit regression framework was used to estimate differences in costs and health outcomes between the two intervention arms during the two-year period. Comet with CPP cost on average 820 EURO more per family than Comet only. At the 2-year follow-up, there were 37% recovered cases of ODD in Comet with CPP, in comparison to 26% in the Comet only arm. At a willingness-to-pay of approximately 62,300 EURO per recovered case of ODD, Comet with CPP yielded positive net benefits, in comparison to Comet only. Offering children the CPP simultaneously as their parents receive PMT, in comparison to only providing PMT, yields clinically relevant gains. Despite the relatively small cost for CPP, investment in combining PMT and CPP should be guided by resource prioritisation. Trial registration number: ISRCTN10834473, date of registration: 23/12/2015.