Objective: To examine the optimal Yale Global Tic Severity Scale (YGTSS) percent reduction and raw cutoffs for predicting treatment response among children and adolescents with tic disorders.
Method: Youth with a tic disorder (N=108; range=5-17 years) participated in several clinical trials involving varied medications or psychosocial treatment, or received naturalistic care. Assessments were conducted before and after treatment and included the YGTSS and response status on the Clinical Global Impressions-Improvement Scale (CGI-I).
Results: A 35% reduction on the YGTSS total tic severity score or a YGTSS raw total tic severity score change of 6 or 7 points were the best indicators of clinical treatment response in youth with tic disorders.
Conclusions: A YGTSS total tic severity score reduction of 35% or a raw total tic severity score change of 6 or 7 appears optimal for determining treatment response. A consistent definition of treatment response on the YGTSS may facilitate cross-study comparability. Practitioners can use these values for treatment planning decisions (e.g., change medications, etc.).