Comparing Health System Costs for Recipients of Minimally Guided Internet-Based Cognitive Behavioural Therapy (iCBT) and Therapist-Guided CBT in Routine Care: A Cohort Study Using Ontario's Linked Health-Administrative Data: Comparaison des coûts pour le système de santé entre les personnes suivant une thérapie cognitivo-comportementale par Internet (TCCI) avec des orientations minimales et les personnes suivant une TCC menée par un ou une thérapeute en soins courants : étude de cohorte utilisant les données administratives de santé liées en Ontario

Objective Internet-based Cognitive Behavioural Therapy (iCBT) is a scalable alternative to therapist-guided CBT, requiring fewer therapist resources. We compared health system costs in individuals receiving minimally guided iCBT (self-directed online modules with asynchronous therapist support) to those receiving therapist-guided CBT (scheduled, one-on-one sessions) in Ontario, Canada (January 2020–August 2021). Methods This retrospective cohort study leveraged linked health-administrative data to estimate person-centred health system costs, overall and mental health (MH)-related, one- and two-years post-treatment for all major healthcare services (emergency departments, hospitalizations, physician visits, long-term/home care, and outpatient prescription drugs). Generalized linear models were used to examine the effect of treatment modality on costs, adjusting for patient sociodemographic characteristics, clinical factors, and pre-treatment healthcare utilization. Results Among N = 167 individuals enrolled in iCBT and N = 300 receiving CBT, we found that iCBT recipients were more likely to use MH-related acute care and outpatient services (primary care physicians and psychiatrists) following treatment. The average MH-specific costs per person were $1,668 for iCBT (95% CI $0, $7,299) and $979 ($0, $4,821) for standard CBT 1-year post-treatment and $4,086 ($0, $17,049) and $2,023 ($0, $9,027), respectively, 2 years post-treatment. However, following regression adjustment for sociodemographic characteristics, baseline symptoms, and pre-treatment MH-related service use, there were no statistically significant differences in one-year and two-year post-treatment total or MH-related costs between the groups ( P > .05). This finding remained robust among individuals meeting criteria for anxiety and depression treatment effectiveness. Conclusions iCBT may represent a scalable approach to expanding access to MH care without significantly increasing long-term health system costs.