Factor-analytic study of the Yale Global Tic Severity Scale.

We report on the factor structure of the Yale Global Tic Severity Scale. Participants were 76 children and adolescents diagnosed with tic disorders. Overall, the model proposed by Leckman et al. [Leckman, J.F., Riddle, M.A., Hardin, M.T., Ort, S.I., Swartz, K.L., Stevenson, J., Cohen, D.J., 1989. The Yale Global Tic Severity Scale: initial testing of a clinician-rated scale of tic severity. Journal of the American Academy of Child and Adolescent Psychiatry 28, 566-573.] represented an adequate fit. The internal consistency of the factors was acceptable and the convergent and divergent validity was supported vis-à-vis correlations with parent ratings of Tourette's Disorder symptoms. These findings support the use of the original scoring structure in assessing pediatric tic severity.