2 - (OP27) The Outcome of Three-day Intensive Group Behavior Therapy for OCD and Related Disorders: Real-world Data of Three Hundreds Patients

Background: Exposure and response prevention (ERP) has been the first-line treatment for obsessive–compulsive disorder (OCD) since the 1990s, and its concepts have increasingly reached the general public. Nevertheless, effective implementation remains challenging. Many clinicians struggle to motivate patients to refrain from compulsions, and self-directed ERP is often carried out incompletely, leading to relapse. To address these barriers, we developed a three-day intensive group behavior therapy (3DI) program for OCD and related disorders in 1998 and established a dedicated outpatient clinic offering 3DI in central Tokyo in 2019.

Methods: We reviewed clinical outcomes for all patients who attended the clinic between 2019 and 2025. During this period, 1,433 individuals presented for evaluation for OCD and related conditions—OCD, hoarding disorder, body dysmorphic disorder, and social anxiety disorder. Of these, 358 elected to participate in 3DI. The program consists of (Day 1) structured psychoeducation; (Day 2) therapist-guided, daylong exposure and response prevention delivered in a small-group format (mean group size 5.5); and (Day 3) repeated exposure practice combined with relapse-prevention planning. Exposure tasks included direct contact with feared stimuli and imagery-based procedures with audio recordings for patients with aggressive or harm-related obsessions.

Outcome measures: OCD severity was assessed using the Yale–Brown Obsessive Compulsive Scale (Y-BOCS). Treatment response (recovery status) was defined as ≥35% reduction from baseline.

Results: Pre-treatment Y-BOCS scores ranged from 16–37 (mean 27.1±4.1), declining to 3–30 post-treatment (mean 12.8±5.2). More than three-quarters of patients met criteria for recovery.

Conclusions: Although uncontrolled, these naturalistic data suggest that 3DI is a feasible and highly effective intervention for OCD and related disorders in routine outpatient practice. Twelve patients required to repeat 3DI due to relapse. Clinical and procedural factors associated with relapse, along with strategies to sustain gains and enhance long-term social functioning, will be discussed.