Remission Trajectories During Low-Intensity Cognitive Behavioural Therapy for Obsessive–Compulsive Disorder: A 2-Year Naturalistic Follow-Up Study

Abstract

Background and Objectives: Cognitive-behavioural therapy (CBT) for obsessive–compulsive disorder (OCD) has primarily been evaluated in short-term, high-intensity treatment protocols. However, remission trajectories during low-intensity CBT (LiCBT) delivered in routine clinical practice remain insufficiently characterised. The aim of this study was to examine 2-year remission trajectories among patients with OCD receiving LiCBT in routine outpatient care. Materials and Methods: This study was a secondary analysis of an ongoing prospective cohort of patients with OCD treated at Hyogo Medical University Hospital, Japan. Patients who had received inpatient treatment or high-intensity CBT were excluded. Symptom severity was assessed using the Yale–Brown Obsessive–Compulsive Scale at baseline, 1 year, and 2 years. Patients were retrospectively classified into early remission, delayed remission, and non-remission groups according to remission timing. Results: Of 62 eligible patients, 47 completed the 2-year follow-up and were included in the remission trajectory analyses. Remission was achieved in 18 patients at 1 year and in an additional 10 patients at 2 years. At baseline, Y-BOCS scores were significantly lower in the early remission group than in the non-remission group, whereas by the 1-year follow-up, Y-BOCS scores differed significantly across all three groups. The delayed remission group did not meet the remission criteria at 1 year and subsequently achieved remission by 2 years. Conclusions: In this naturalistic multimodal treatment setting that included LiCBT, remission followed heterogeneous temporal trajectories rather than a single uniform course. The findings suggest that remission should not be evaluated solely within the first year of treatment and highlight the clinical importance of longitudinal assessment in routine outpatient care.