The Huntington’s Disease Health Index: Initial Evaluation of a Disease-Specific Patient Reported Outcome Measure

• Published in: Journal of Huntington's disease 2022, Vol.11 (2), p.217-226
• Main Authors: Brumfield, Olivia S., Zizzi, Christine E., Dilek, Nuran, Alexandrou, Danae G., Glidden, Alistair M., Rosero, Spencer, Weinstein, Jennifer, Seabury, Jamison, Kaat, Aaron, McDermott, Michael P., Dorsey, E. Ray, Heatwole, Chad R.
• Format: Article
• Language: English
• Subjects: Clinical trials; Cognitive ability; Factor analysis; Huntington's disease; Huntingtons disease; Patients; Product development
• ISSN: 1879-6397; 1879-6397
• DOI: 10.3233/JHD-210506

Background: When developed properly, disease-specific patient reported outcome measures have the potential to measure relevant changes in how a patient feels and functions in the context of a therapeutic trial. The Huntington’s Disease Health Index (HD-HI) is a multifaceted disease-specific patient reported outcome measure (PROM) designed specifically to satisfy previously published FDA guidance for developing PROMs for product development and labeling claims. Objective: In preparation for clinical trials, we examine the validity, reliability, clinical relevance, and patient understanding of the Huntington’s Disease Health Index (HD-HI). Methods: We partnered with 389 people with Huntington’s disease (HD) and caregivers to identify the most relevant questions for the HD-HI. We subsequently utilized two rounds of factor analysis, cognitive interviews with fifteen individuals with HD, and test-retest reliability assessments with 25 individuals with HD to refine, evaluate, and optimize the HD-HI. Lastly, we determined the capability of the HD-HI to differentiate between groups of HD participants with high versus low total functional capacity score, prodromal versus manifest HD, and normal ambulation versus mobility impairment. Results: HD participants identified 13 relevant and unique symptomatic domains to be included as subscales in the HD-HI. All HD-HI subscales had a high level of internal consistency and reliability and were found by participants to have acceptable content, relevance, and usability. The total HD-HI score and each subscale score statistically differentiated between groups of HD participants with high versus low disease burden. Conclusion: Initial evaluation of the HD-HI supports its validity and reliability as a PROM for assessing how individuals with HD feel and function.