Defining clinical severity in adults with obsessive-compulsive disorder

Objective: The Yale Brown Obsessive Compulsive Scale (Y-BOCS) is the most commonly used instrument to assess the clinical severity of obsessive compulsive symptoms. Treatment determinations are often based on Y-BOCS score thresholds. However, these benchmarks are not empirically based, which may result in non-evidence based treatment decisions. Accordingly, the present study sought to derive empirically-based benchmarks for defining obsessive compulsive symptom severity. Method: Nine hundred fifty-four adult patients with obsessive compulsive disorder (OCD), recruited through the Brazilian Research Consortium on Obsessive Compulsive Spectrum Disorders, were evaluated by experienced clinicians using a structured clinical interview, the Y-BOCS, and the Clinical Global Impressions Severity scale (CGI-Severity). Results: Similar to results in treatment-seeking children with OCD, our findings demonstrated convergence between the Y-BOCS and global OCD severity assessed by the CGI-Severity (Nagelkerke R-2 = .48). Y-BOCS scores of 0-13 corresponded with 'mild symptoms' (CGI-Severity = 0-2), 14-25 with 'moderate symptoms' (CGI-Severity = 3), 26-34 with 'moderate-severe symptoms' (CGI-Severity = 4) and 35-40 with 'severe symptoms' (CGI-Severity = 5-6). Neither age nor ethnicity was associated with Y-BOCS scores, but females demonstrated more severe obsessive compulsive symptoms than males (d = .34). Time spent on obsessions/compulsions, interference, distress, resistance, and control were significantly related to global OCD severity although the symptom resistance item pairing demonstrated a less robust relationship relative to other components of the Y-BOCS. Conclusions: These data provide empirically-based benchmarks on the Y-BOCS for defining the clinical severity of treatment seeking adults with OCD, which can be used for normative comparisons in the clinic and for future research. (C) 2015 Elsevier Inc. All rights reserved.