Assessment of the Performance of a Modified Motor Scale as Applied to Juvenile Onset Huntington's Disease.

Horton, Mike C; Nopoulos, Peggy; Nance, Martha; Landwehrmyer, G Bernhard; Barker, Roger A; Squitieri, Ferdinando; Burgunder, Jean-Marc; Quarrell, Oliver (2019). Assessment of the Performance of a Modified Motor Scale as Applied to Juvenile Onset Huntington's Disease. Journal of Huntington's disease, 8(2), pp. 181-193. IOS Press 10.3233/JHD-180306

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BACKGROUND Huntington's disease can present at almost any age but traditionally, those with an onset ≤20 years are described as having juvenile onset Huntington's disease (JOHD). They are more likely to have bradykinesia and dystonia earlier in the course of the disease. The Total Motor Score of the Unified Huntington's Disease Rating Scale (UHDRS-TMS) is often used as the principal outcome measure in clinical trials. OBJECTIVE To identify a motor scale more suitable for JOHD patients. METHODS A working group reviewed the UHDRS-TMS and modified it by adding four further assessment items. Rasch analysis was used to study the performance of the modified scale in 95 patients with a mean age of 19.4 (SD 6.6) years. RESULTS The initial analysis showed a significant overall misfit to the Rasch model and a number of individual items displayed poor measurement properties: all items relating to chorea displayed significant misfit due to under-discrimination. Additionally, a number of items displayed disordered response category thresholds, and a large amount of dependency was present within the item set (96 out of 741 pairwise differences = 13%). An iterative process of scale re-structuring and evaluation was then undertaken, with a view to eliminating the largest sources of misfit and generating a set of items that would conform to Rasch model expectations. CONCLUSION This post-hoc scale restructuring appears to provide a valid motor score that is psychometrically robust in a JOHD population. This scale restructuring offers a pragmatic solution to measuring motor function in a JOHD population, and it could provide the basis for the further iterative development of a more useful clinical rating scale for patients with JOHD.

Item Type:

Journal Article (Original Article)

Division/Institute:

04 Faculty of Medicine > Department of Head Organs and Neurology (DKNS) > Clinic of Neurology

UniBE Contributor:

Burgunder, Jean-Marc

Subjects:

600 Technology > 610 Medicine & health

ISSN:

1879-6400

Publisher:

IOS Press

Language:

English

Submitter:

Chantal Kottler

Date Deposited:

30 Dec 2019 10:25

Last Modified:

30 Dec 2019 10:25

Publisher DOI:

10.3233/JHD-180306

PubMed ID:

30856116

Uncontrolled Keywords:

Rasch juvenile onset Huntington’s disease total motor score

BORIS DOI:

10.7892/boris.136827

URI:

https://boris.unibe.ch/id/eprint/136827

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