Outcome measures

The clinical severity of OCD symptoms will be measured by the Yale-Brown Obsessive Compulsive Scale (Y-BOCS),^32–34 a self-report, 10-item questionnaire extensively used in research and clinical practice to monitor improvement during treatment. The Y-BOCS consists of two parts: the Symptom Checklist for evaluating the presence of current and past symptoms, and the 10-item Severity Scale (rated 0–4 per item) that assesses obsessions and compulsions separately in five dimensions (time spent, interference, distress, resistance and control). Separate Obsession (items 1–5) and Compulsion (items 6–10) subscale scores (range 0–20) are summed to yield a total Y-BOCS score (range 0–40).³⁵ Depressive symptoms will be assessed by the Beck Depression Inventory-II (BDI-II),^{36 37} a 21-question, multiple-choice, self-report inventory widely used for measuring the severity of depression.