F096 Development of assessments for later stage Huntington’s disease: HD- structured interview of function and hd clinical status questionnaire – the ‘later stage HD assessments’ study (LSA)

<h3>Background</h3> There is a need for validated assessments for patients with later-stage HD. This study aims to evaluate the clinimetric properties for two such measures: the HD Structured Interview of Function (HD-SIF) and HD Clinical Status Questionnaire (HDCSQ). Both assessments are administered to a companion either in-person or remotely (by phone), and the properties of these tests are being evaluated in a two-part study using the methods of Classical Test Theory (CTT) and Item Response Theory (IRT). <h3>Methods</h3> 170 dyads of people with Huntington’s disease and their companions will be enrolled. The study includes two parts. In Part 1, we are using the methods of CTT to evaluate the HD-SIF, a structured interview designed to gather information for making ratings on the UHDRS ‘99 functional scales (TFC, FAS and IS). In Part 2, we are using the methods of CTT and IRT to assess the clinimetric properties of the HDCSQ, a questionnaire designed specifically to capture information on disease milestones that occur during the later stages of HD, and the HD-SIF. <h3>Current status and outlook</h3> Four US sites have recruited 18 dyads in Part 1 and 15 dyads in Part 2. Preliminary results from Part 1 will be available at the end of 2024. Part 2 began in June 2022 with preliminary results expected at the end of 2025. These assessments will be incorporated in the upcoming Enroll-HD 2.0 protocol and may be used in the future for planning studies or for other observational and interventional studies of HD.