Measurement Properties of the Dysphagiameter for the Assessment of Dysphagia in Oculopharyngeal Muscular Dystrophy.

Oculopharyngeal muscular dystrophy (OPMD) is a rare late-onset muscle disease with progressive dysphagia as a major symptom. The Dysphagiameter is a newly developed patient-reported outcome measure (PROM) to assess the severity of dysphagia and its impact in patients with OPMD. This article reports on item reduction and a first assessment of the Dysphagiameter's psychometrics properties, in a French and English-speaking population of individuals with OPMD. Classical test theory and Rasch model were used for item reduction and scoring (n = 162). Construct validity was assessed using the time to drink 80 ml of cold water and the Sydney Swallow Questionnaire (SSQ) (n = 40). Part A of the final PROM resulted in a 21-item scale assessing the capacity to swallow foods of various textures and a 3-item scale assessing the capacity to swallow liquids (Cronbach Alpha = 0.90); the hierarchical structure of the 21-item scale was confirmed with a Rasch analysis (Person separation index = 0.95). Part B resulted in a 6 item-scale assessing the impact on mealtime and a 2-item scale assessing discomfort related to thick saliva (Alpha Cronbach = 0.91 and 0.79). Convergent validity was demonstrated by significant correlations with the SSQ. Known-group validity was supported by the ability of the Dysphagiameter to detect significant differences according to the severity of dysphagia. In summary, the Dysphagiameter-OPMD, a newly developed PROM, exhibits strong psychometric properties and holds promise as a valuable tool for assessing the severity of dysphagia and its impact on individuals with OPMD.