A teaching videotape for the assessment of essential tremor

Teaching videotapes, developed to aid in the evaluation of several movement disorders, have not been used in essential tremor research. As part of the Washington Heights-Inwood Genetic Study of Essential Tremor (WHIGET), we developed a reliable and valid tremor rating scale. Because this rating scale is currently being used by investigators at other centers, we developed a teaching videotape to aid in the consistent application of this scale. OBJECTIVE: To develop a teaching videotape for a revised version of the WHIGET Tremor Rating Scale and to assess the interrater agreement among raters who used this videotape to rate tremor. METHODS: The revised WHIGET Tremor Rating Scale was used to rate action tremor from 0 to 4 during six tests: arm extension, pouring, drinking, using a spoon, finger-to-nose, and drawing spirals. A 22-minute teaching videotape was developed that includes a 29-item educational section and a self-assessment section consisting of 20 examples of tremor ratings chosen by the two WHIGET study neurologists. Eight raters, including senior movement disorder specialists, movement disorder fellows, general neurologists, and a movement disorder nurse practitioner, independently viewed the videotape and rated tremor during the self-assessment section. Interobserver reliability was assessed with weighted kappa statistics (κ_w). RESULTS: Eight raters each rated 20 items (160 ratings total). Total κ_w was 0.97 (nearly perfect agreement). Interrater reliability was as follows: κ_w = 0.99 (movement disorder specialists), κ_w = 0.98 (movement disorder fellows), and κ_w = 0.97 (general neurologists); all κ_w were nearly perfect. CONCLUSIONS: This teaching videotape may be used to improve the uniform application of the revised WHIGET Tremor Rating Scale by raters with various levels of experience in movement disorders.