Cutoff Points for Commonly Used Instruments to Assess Mental Health Problems Among Adults With Tourette's Syndrome

Attention-deficit hyperactivity disorder, obsessive-compulsive disorder, depression, and anxiety are highly comorbid in Tourette's syndrome. Cutoff points of screening instruments for these conditions have been validated in the general population. The authors assessed whether established cutoff points on the General Anxiety Disorder-7 (GAD-7) scale; Patient Health Questionnaire-9 (PHQ-9); PHQ-2; Adult ADHD Self-Report Scale, version 1.1 (ASRS v1.1); and Obsessive-Compulsive Inventory (OCI) need to be adjusted for adults with Tourette's syndrome.

Thirty-six adults with Tourette's syndrome completed these instruments and a diagnostic psychiatric interview. Measures of diagnostic accuracy were calculated (area under the receiver operating characteristic curve [AUC], sensitivity, specificity, positive predictive value, negative predictive value, positive likelihood ratio, and negative likelihood ratio) for each instrument at various cutoffs. Cutoffs for the sample of adults with Tourette's syndrome were suggested by the lowest value derived from a Euclidean distance method.

In this sample of adults with Tourette's syndrome, the optimal cutoff points were a GAD-7 score ≥13 (sensitivity, 67%; specificity, 91%; and AUC, 79%), a PHQ-9 score ≥15 (sensitivity, 67%; specificity, 73%; and AUC, 70%), a PHQ-2 score ≥3 (sensitivity, 67%; specificity, 67%; and AUC, 67%), an ASRS v1.1 score ≥14 (sensitivity, 83%; specificity, 77%; and AUC, 80%), and an OCI score ≥63 (sensitivity, 70%; specificity, 89%; and AUC, 79%). The best-performing instrument was the ASRS v1.1, followed by the GAD-7 and OCI; the PHQ-9 and PHQ-2 performed least well in this population.

Further research is needed to adapt screening instruments for the assessment of comorbid conditions among patients with Tourette's syndrome.