Abstract
This study investigated the long-term effectiveness and cost-effectiveness of guided internet-based cognitive behavioral therapy (ICBT) for obsessive-compulsive disorder (OCD). Twenty-five patients with OCD who had undergone guided ICBT in a randomized controlled trial or a single-arm trial were followed up for 6, 12, and 24 months. Missing data were imputed using the mice package in R, and a one-way analysis of variance with repeated measures was performed. The total Yale-Brown Obsessive-Compulsive Scale (Y-BOCS) score significantly decreased from baseline to all endpoints (p < 0.001). OCD remission (the total Y-BOCS score < 14) rates significantly increased from post-treatment (48 %) at the 12 months (80 %) and 24 months (76 %) follow-up (χ2 (1) = 7.11-11.08, p < 0.01) post guided ICBT. Regression analysis predicted the maintenance of remission at 12 and 24 months following post-treatment remission (z = 2.20, p = 0.03). An incremental cost-effectiveness ratio was calculated to assess the cost-effectiveness of guided ICBT. The incremental cost-effectiveness ratio was JPY 999,495, below the JPY 5 million threshold for willingness to pay in Japan. Our findings demonstrate the long-term effectiveness and cost-effectiveness of guided ICBT for OCD. Guided ICBT can mitigate the severity of OCD even after treatment.