Objective: To enhance understanding of the composite Unified Huntington’s Disease Rating Scale (cUHDRS) scoring by linking to established measures of meaningful daily function and independence in individuals with early-to-moderate-manifest Huntington’s disease (HD).

Background: The cUHDRS is a novel scoring algorithm that provides a relatively holistic and sensitive outcome assessment of cognitive, motor and functional impairment in early-to-moderate-manifest HD. It combines the Total Functional Capacity (TFC), Total Motor Score, Symbol Digit Modalities Test and Stroop Word Reading measures into a single metric. To aid score interpretation, it is important to understand what this score means in terms of typical functional status.

Method: Data from Enroll-HD were evaluated. For patients meeting the reference population for the cUHDRS (manifest HD, TFC 5–13, ≥20 years; N=3,490), the cUHDRS score range was calculated. Patients were divided into groups around each integer score (e.g., for cUHDRS=11: 10.5≤cUHDRS score<11.5). For each grouping, the mean HD stage, Independence Scale (IS) score, mean Functional Assessment (FA) score and number of FA items that ≥50% of individuals can achieve were calculated.

Results: In this population, cUHDRS score groupings ranged 2–18; however, only six individuals were cUHDRS=2, and so this grouping was excluded from subsequent analyses, leaving a range of 3–18 (N=3,484). For those patients in the 14–18 cUHDRS score groupings, ≥50% were able to achieve all 25 FA items and had a mean IS of 95. As cUHDRS scores declined, the number of FA items achievable and the level of independence declined. For patients in the lowest cUHDRS score group, cUHDRS=3 points, only 12 FA items were achievable by ≥50% and the mean IS=65. A figure was created, incorporating these results, to provide a simple guide to aid interpretation of cUHDRS scores, by linking cUHDRS scores to the measures of functional ability.

Conclusion: cUHDRS scores reflect the differing levels of function in individuals with early-to-moderate-manifest HD. Furthermore, the cUHDRS can better differentiate between individuals with Stage 1 HD than commonly used measures of function. The visual aid described here can be used to relate cUHDRS score to functional status in patients with HD.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/using-functional-status-to-aid-interpretation-of-cuhdrs-scores-in-patients-with-huntingtons-disease/