Cognitive impairment in Huntington's disease and its impact on functioning: Concept elicitation and cognitive debriefing for the Huntington's Disease Everyday Functioning (Hi-DEF) scale.

BACKGROUND

Cognitive impairment in Huntington's disease (HD) is a key driver of disability that can have deleterious impacts on everyday functioning. Currently available patient-reported outcome measures may not adequately capture the impact of HD-related cognitive impairment on daily life, particularly higher-order executive functioning (i.e., processing information, decision making, multi-tasking, planning, etc.).

OBJECTIVE

To address the unmet need to better quantify the functional sequelae of HD-related cognitive impairment by developing the Huntington's Disease Everyday Functioning (Hi-DEF) scale.

METHODS

Qualitative interviews were conducted in two adult cohorts (25-65 years) with early stages of HD (i.e., huntingtin [mHTT] gene carriers with self-reported cognitive complaints but could still function independently). Cohort 1 included 10 dyads of participants with HD and their care partners, who completed concept elicitation interviews to identify cognitive challenges impacting everyday tasks, which was used to design a draft item-set. Cohort 2, which included 15 additional participants with HD, cognitively debriefed this item-set.

RESULTS

In Cohort 1, issues with executive functioning were reported 32 times by participants with HD and 22 times by care partners, and challenges with functioning were reported 46 times by participants with HD and 20 times by care partners. Based on these reports, the Hi-DEF scale was developed and cognitive debriefing interviews evaluated its content validity, relevance, clarity, interpretation, and acceptability. Psychometric validation of the Hi-DEF scale is reported elsewhere.

CONCLUSIONS

These interviews revealed the impact of HD-related cognitive impairment on everyday functioning and supported the content validity, relevance, clarity, interpretation, and acceptability of the Hi-DEF scale.