Glenn T Stebbins, Charles H Adler, Alberto Albanese, Richard L Barbano, Anna Rita Bentivoglio, Carlo Colosimo, Maria Fiorella Contarino, Dirk Dressler, Stewart A Factor, Susan H Fox, Victor S C Fung, Christopher G Goetz, Joseph Jankovic, Hyder A Jinnah, Wolfgang H Jost, Marina A J Tijssen, Elena Moro, Joel S Perlmutter, Stephen G Reich, Ramon L Rodriguez, Lawrence Severt, Natividad P Stover, Marie Vidailhet, Julianne Lee, Cynthia L Comella, David A Peterson
The TWSTRS-Delphi yields reproducible Total and item scores across movement disorder raters. The data pinpoint Sagittal Shift, Duration, and Sensory Tricks as the principal sources of between-rater variability, defining immediate priorities for scale modification and focused training.
BACKGROUND: Cervical dystonia (CD) motor severity is typically quantified with the Toronto Western Spasmodic Torticollis Rating Scale (TWSTRS). An expanded version of the Motor Severity section of the TWSTRS ("TWSTRS-Delphi") has been previously evaluated for its clinimetric properties but not for inter- and intrarater reliability.
OBJECTIVE: In this study we quantified inter- and intrarater reliability of the Motor Severity section of the TWSTRS-Delphi for CD.
METHODS: Ten raters familiar with the TWSTRS-Delphi and ten raters unfamiliar with it independently scored standardized videos from 90 patients with CD. We computed one-way random intraclass correlation coefficient (ICC, absolute agreement) for total and item scores. We repeated assessments and calculations with a subset of raters to assess intrarater reliability.
RESULTS: Interrater reliability for the Total score was good for Familiar raters (ICC = 0.697) and fair for Unfamiliar raters (ICC = 0.566). Most individual items achieved fair-excellent interrater agreement in both groups (Familiar 0.415-0.763; Unfamiliar 0.416-0.769). Sagittal Shift, Duration, and Sensory Tricks showed poor agreement. Intrarater reliability was fair-excellent for most items in both groups (Familiar 0.494-0.927; Unfamiliar 0.413-0.877), but poor for Sagittal Shift and Duration among Familiar raters.
CONCLUSIONS: The TWSTRS-Delphi yields reproducible Total and item scores across movement disorder raters. The data pinpoint Sagittal Shift, Duration, and Sensory Tricks as the principal sources of between-rater variability, defining immediate priorities for scale modification and focused training.