Evaluating swallowing function in patients with Huntington disease enrolled in the first-HD study

Objective: The Swallowing Disturbance Questionnaire (SDQ) was administered to patients with Huntington disease (HD) as part of a randomized, controlled study of deutetrabenazine for the treatment of chorea of HD. Here we describe the impact of deutetrabenazine on swallowing. Background: Swallowing function is an important clinical problem in patients with HD, but dysphagia severity is not surveyed or quantified in the Unified Huntington Disease Rating Scale (UHDRS). The SDQ is a 15‐item survey developed and validated to assess swallowing dysfunction in Parkinson's disease (PD) and has been shown to reliably detect swallowing impairment arising from various etiologies other than PD. It is recommended in the Parkinsonism National Institute of Neurological Disorders and Stroke Common Data Elements. This is the first time the SDQ was used as a screening tool and swallowing assessment in HD. Methods: Participants with HD (N=90) were randomized 1:1 to receive deutetrabenazine or placebo in a 12‐week multicenter Phase III trial that included an eight‐week titration. A normal SDQ score (<11) was required at screening. SDQ and patient weight data were collected at baseline and Weeks 2, 4, 6, 9, and 12. Reports of dysphagia as an adverse event were monitored up to Week 12. Results: A number of screening failures were attributed to high SDQ scores at baseline (n=8). Deutetrabenazine improved SDQ score 1.2 (SE 0.4) versus worsening placebo 0.3 (SE 0.4) at Week 9 (P=.014), which was maintained up to Week 12 (P=.016). No deutetrabenazine‐treated patients and one patient given placebo reported dysphagia as an adverse event. There was a 2.1‐kg treatment effect for weight gain in deutetrabenazine‐treated patients at Week 12, Conclusions: Deutetrabenazine significantly improved swallowing function, as measured by SDQ, which may have contributed to the observed weight gain in deutetrabenazine‐treated patients with HD. However, since swallowing was in the normal range for all participants, given the improved swallowing function in deutetrabenazine‐treated patients, further study of chorea‐associated dysphagia is warranted. These results obtained using the SDQ in HD support future validation of this scale including HD specific "normal" cutoffs to assess swallowing function in this population.