Supplementary Material for: Psychosocial Impact of Dysarthria: The Patient-Reported Outcome as Part of the Clinical Management

Background: Dysarthria in neurological disorders can have psychosocial consequences. The dysarthric speaker’s perspective towards the disorder’s psychosocial impact is essential in its global assessment and management. For such purposes, assessment tools such as the Dysarthria Impact Profile (DIP) are indispensable. Objective: We aimed to confirm the relevance of using the DIP to quantify the psychosocial consequences of dysarthria in neurological diseases. Methods: We studied 120 participants, 15 healthy controls and 105 patients with different kinds of dysarthria induced by several neurological disorders (Parkinson’s disease [PD], Huntington’s disease, dystonia, cerebellar ataxia, progressive supranuclear palsy [PSP], multiple system atrophy, lateral amyotrophic sclerosis). All participants underwent a cognitive evaluation and a speech intelligibility assessment and completed three self-reported questionnaires: the 36-Item Short Form Health Survey, the Voice Handicap Index (VHI), and the DIP. Results: The psychometric properties of the DIP were confirmed, including internal consistency (α = 0.93), concurrent validity (correlation with the VHI: r = –0.77), and discriminant validity (accuracy = 0.93). Psychosocial impact of dysarthria was revealed by the DIP for all patients. Intelligibility loss was found strongly correlated with the psychosocial impact of dysarthria: for a similar level of intelligibility impairment, the DIP total score was similar regardless of the pathological group. However, our findings suggest that the psychosocial impact measured by the DIP could be partially independent from the severity of dysarthria (indirectly addressed here via speech intelligibility): the DIP was able to detect patients without any intelligibility impairment, but with a psychosocial impact. Conclusions: All patients reported a communication complaint, attested by the DIP scores, despite the fact that not all patients, notably PD, ataxic, and PSP patients, had an intelligibility deficit. The DIP should be used in clinical practice to contribute to a holistic evaluation and management of functional communication in patients with dysarthria.