Cost-effectiveness of internet-delivered cognitive-behavioural therapy for adolescents with irritable bowel syndrome

Objective To assess whether exposure-based internetdelivered cognitive-behavioural therapy (internet-CBT) is a cost-effective treatment for adolescents with irritable bowel syndrome (IBS) compared with a waitlist control, from a societal perspective, based on data from a randomised trial. Design Within-trial cost-effectiveness analysis. Setting Participants were recruited from the whole of Sweden via primary, secondary and tertiary care clinics reached through news media and advertising. Participants Adolescents (aged 13-17) with a diagnosis of IBS. Interventions Participants were randomised to either an exposure-based internet-CBT, including 10 weekly modules for adolescents and five modules for parents, or a waitlist. Outcome measures The main health outcome was the quality-adjusted life-year (QALY) estimated by mapping Pediatric Quality-of-Life Inventory (PedsQL) scores onto EQ-5D-3L utilities. The secondary outcome was the point improvement on the PedsQL scale. Data on health outcomes and resource use were collected at baseline and 10 weeks post-treatment. Resource use was measured using the Trimbos and Institute of Medical Technology Assessment Cost Questionnaire for Psychiatry (TIC-P). Incremental cost-effectiveness ratios (ICER) were calculated as the difference in average costs by the difference in average outcomes between groups. Results The base-case results showed that internetCBT costs were on average US$ 170.24 (95% CI 63.14 to 315.04) more per participant than the waitlist. Adolescents in the internet-CBT group showed small QALY gains (0.0031; 95% CI 0.0003 to 0.0061), and an average improvement of 5.647 points (95% CI 1.82 to 9.46) on the PedsQL compared with the waitlist. Internet-CBT yielded an ICER of $54 916/QALY gained and a probability of cost-effectiveness of 74% given the Swedish willingnessto-pay threshold. The ICER for the outcome PedsQL was US$ 85.29/ point improvement. Conclusions Offering internet-CBT to adolescents with IBS improves health-related quality of life and generates small QALY gains at a higher cost than a waitlist control. Internet-CBT is thus likely to be cost-effective given the strong efficacy evidence, small QALY gains and low cost.