Psychometric Assessment of the Unified Tic Severity Scale (UTSS)

Grant Type
Grant Year
Institution Location
Institution Organization Name
University of Rochester
Investigators Name
Como, Peter, PhD

Development of a rating scale to be universally applied for the measurement of tic severity was initiated by the Tourette Syndrome Association (TSA) in May, 1988. Sponsored by the TSA, a workshop meeting was convened in New York City and included nationally recognized experts in Tourette Syndrome (TS) representing areas of basic science, genetics and clinical practice. Both clinicians and researchers have used a variety of rating scales for TS, including ratings of tic characteristics and associated behavioral features such as attention deficit hyperactivity disorder (ADHD) and obsessive-compulsive disorder (OCD). However, research studies of TS have been hampered by the lack of a single, unified rating scale of tic characteristics. Moreover, the existing tic rating scales do not adequately address all aspects of tic characteristics (e.g., frequency, suppression) and only a small number of published tic rating scales have been subjected to rigorous psychometric assessment. Earlier versions of the group’s Unified Tic Severity Scale (UTSS) were field tested and psychometrically assessed. Based upon these results and the feedback of the rating scale steering committee, the UTSS has been significantly revised and now requires careful psychometric assessment before it can be used universally. We plan to assess the psychometric properties of the UTSS via: (1) an interrater reliability study using 36 subjects with TS and 3 raters, (2) a test-retest (intrarater) reliability study, and (3) a validity study using 26 additional subjects. Raters for the interrater reliability study will include two outside experts in TS and two in Rochester, NY. Subjects will be interviewed by the raters who will complete the UTSS. The subjects interviewed by the two Rochester raters will return for a second interview approximately two weeks after the first interview to complete the test-retest reliability portion of this study. For the validity study, scores on the UTSS will be correlated with existing tic rating scales and a videotaped rating. The intraclass correlation coefficient will be used to analyze data obtained from the interrater and test-retest reliability studies. Spearman and Pearson correlation coefficients will be used to analyze data from the validity study. A universally-accepted tic rating scale has widespread implications. Most importantly, it can aid in the quantification and clarification of TS features which, by definition, are heterogeneous and difficult to evaluate. Consequently, a unified rating scale can provide a more standardized method for evaluating TS among clinicians and researchers. In addition, a unified tic rating scale can serve as an impetus for developing a centralized TS database for multicenter research studies such as clinical therapeutic trials and genetic studies. Peter G. Como, Ph.D., Michael McDermott, Ph.D., University of Rochester Medical Center, Rochester, NY Patrick Shrout, Ph.D., New York University, New York, NY Award $24,530 Tourette Association of America Inc. – Research Grant Award 1995