Brief intervention, lasting impact: One-year outcomes of the Bergen 4-day treatment for OCD in Germany

Background Obsessive–compulsive disorder (OCD) is a prevalent and highly disabling mental disorder. Worldwide, it is associated with substantial individual suffering and long-term societal costs. Although exposure and response prevention (ERP) is the recommended first-line treatment, access to effective care remains limited for reasons such as long treatment duration. These barriers contribute to persistent global treatment gaps. The Bergen 4-Day Treatment (B4DT) is a brief, concentrated form of ERP (cERP) designed to improve treatment efficiency and access. Although initial outcomes are promising, long-term data from countries other than Norway are limited. This study evaluated the 12-month outcomes of the B4DT in a German day-patient treatment setting, exploring its sustained effectiveness and feasibility outside its original context. Methods Fifty-eight adults with OCD received B4DT in an uncontrolled study and were reassessed 12 months after treatment. The primary outcome was OCD severity, assessed with the Yale-Brown Obsessive Compulsive Scale (Y-BOCS). Secondary outcomes included depressive symptoms, global functioning, self-efficacy, experiential avoidance, self-esteem, quality of life, and mental health service utilization. Results Large reductions in OCD symptom severity (Y-BOCS) and significant improvements across most secondary outcomes were sustained at the 12-month follow-up. One year after treatment, 69% of participants met criteria for treatment response, 51% had achieved remission, and 78% showed reliable clinical improvement. No clinically relevant symptom deterioration was observed, and treatment acceptability and follow-up retention were high. Importantly, only a small proportion of patients ( n = 4; 7%) required inpatient treatment during the follow-up period. Conclusion These findings demonstrate that brief cERP can achieve durable clinical benefits for patients with OCD when implemented outside its original context. From a global mental health and health policy perspective, the combination of short treatment duration, sustained effectiveness, and low subsequent use of inpatient services suggests that cERP represents a scalable and resource-efficient strategy to expand access to evidence-based OCD treatment across diverse health care systems.