Reducing Maximal Support in OCD: Efficacy of Stepped-Care Online CBT

This study is conducted to explore the efficacy and cost-effectiveness of stepped-care internet-based cognitive behavior therapy (sc-ICBT) with reduced support compared to cognitive-behavioral group therapy(CBGT), to identify the optimal transition points for shorter effective stepped treatments, to find clinical indicators that can predict the effectiveness of CBT interventions, and to investigate predictive outcomes. The main questions the investigators aim to answer are: 1. Is the reduction in YBOCS scores following stepped-care Internet-based cognitive-behavioral therapy (SC-ICBT) with reduced support non-inferior to that observed in traditional cognitive-behavioral group therapy (CBGT)? 2. Does SC-ICBT for obsessive-compulsive disorder offer better health economic benefits compared to CBGT? 3. What is the optimal time point for transitioning to shorter effective stepped care, and what clinical indicators can predict the efficacy of CBT interventions post-treatment?