Clinical validation of the parent-report Toronto Obsessive-Compulsive Scale (TOCS): A pediatric open-source rating scale

Laura J Lambe; Christie L Burton; Evdokia Anagnostou; Elizabeth Kelley; Robert Nicolson; Stelios Georgiades; Noam Soreni; Russell J Schachar; Gregory L Hanna; Paul D Arnold; Jennifer Crosbie

doi:10.1002/jcv2.12056

Clinical validation of the parent-report Toronto Obsessive-Compulsive Scale (TOCS): A pediatric open-source rating scale

JCPP Adv. 2021 Dec 3;1(4):e12056. doi: 10.1002/jcv2.12056. eCollection 2021 Dec.

Authors

Laura J Lambe¹, Christie L Burton¹, Evdokia Anagnostou^{2

3}, Elizabeth Kelley⁴, Robert Nicolson⁵, Stelios Georgiades⁶, Noam Soreni^{6

7}, Russell J Schachar^{1

8}, Gregory L Hanna⁹, Paul D Arnold^{10

11

12}, Jennifer Crosbie^{1

8}

Affiliations

¹ Program of Neurosciences and Mental Health Hospital for Sick Children Toronto Ontario Canada.
² Bloorview Research Institute Holland Bloorview Kids Rehabilitation Hospital Toronto Ontario Canada.
³ Department of Pediatrics University of Toronto Toronto Ontario Canada.
⁴ Department of Psychology Queen's University Kingston Ontario Canada.
⁵ Schulich School of Medicine and Dentistry University of Western Ontario London Ontario Canada.
⁶ Department of Psychiatry & Behavioural Neurosciences McMaster University Hamilton Ontario Canada.
⁷ Department of Psychiatry St. Joe's Healthcare Hamilton Ontario Canada.
⁸ Department of Psychiatry University of Toronto Toronto Ontario Canada.
⁹ Department of Psychiatry University of Michigan Ann Arbor Michigan USA.
¹⁰ The Mathison Centre for Mental Health Research & Education Calgary Alberta Canada.
¹¹ Departments of Psychiatry and Medical Genetics, Cumming School of Medicine University of Calgary Calgary Alberta Canada.
¹² Program of Genetics and Genome Biology Hospital for Sick Children Toronto Ontario Canada.

Abstract

Background: There is a need to develop a multipurpose obsessive-compulsive disorder (OCD) measure that is useful for cross disorder research and as a reliable clinical rating scale. The current study examined the psychometric properties and established clinical cutoffs for the parent-report version of the Toronto Obsessive-Compulsive Scale (TOCS), a 21-item rating scale of obsessive-compulsive traits.

Method: Participants ranged in age from 6 to 21 years old and had a primary diagnosis of OCD (n = 350, 50% female), attention-deficit/hyperactivity disorder (ADHD) (n = 820, 25% female), autism spectrum disorder (ASD) (n = 794, 22% female), or were typically developing controls (n = 391, 51% female). Confirmatory factor analyses, internal consistency reliability, and convergent and divergent validity of the TOCS were examined in the OCD group. Using various scoring approaches, receiver operating characteristic (ROC) analyses were used to establish a clinical cut-off by splitting the OCD group into a discovery sample (166 OCD cases, 164 controls) and a validation sample (184 OCD cases, 227 controls). Classification accuracy and TOCS scores were compared across OCD, ADHD, and ASD groups.

Results: The psychometric properties of the TOCS were confirmed. ROC analyses across TOCS scoring approaches in the discovery sample indicated excellent diagnostic discrimination (AUC ≥0.95, sensitivity 77%-92%, specificity 92%-98%). Established cutoffs, when applied in the independent validation sample of OCD cases and controls, showed an overall classification accuracy of 85%-90%. The TOCS total score and symptom count showed good discrimination of OCD from ADHD (AUC ≥0.86) and ASD (AUC ≥0.81). The OCD group scored significantly higher on all TOCS dimensions (except Hoarding) than the ADHD and ASD groups.

Conclusion: The TOCS is a reliable and valid rating scale with strong sensitivity and specificity in discriminating OCD cases from controls, as well as from ASD and ADHD. It is a quantitative OCD measure with important clinical and research applications, with particular relevance for cross disorder phenotyping and population-based studies.

Keywords: ROC analysis; cross‐disorder phenotyping; neurodevelopmental disorders; obsessive–compulsive disorder; obsessive–compulsive traits; scale development.