Background: Few valid, disease‐specific measures of health‐related quality of life (HRQOL) capture the spectrum of symptoms associated with Huntington's disease (HD). The HD‐PRO‐TRIAD™ is a new, HD‐specific, patient‐reported outcome (PRO) instrument of the HD symptom triad (cognitive decline, emotional/behavioral dyscontrol, and motor dysfunction) designed for clinical research and practice. The objective was to validate the HD‐PRO‐TRIAD™ through a cross‐sectional sample of individuals with HD and caregivers.
Methods: Development of the HD‐PRO‐TRIAD™ has been described elsewhere. A total of 132 individuals with HD and 40 HD caregivers, comprising 29 dyads, participated in the cross‐sectional psychometric validation of this instrument. Participants provided responses to the HD‐PRO‐TRIAD™ and other HRQOL and disease severity instruments (EuroQOL 5D, Short Form 12, Neuro‐QOL Item Banks, PROMIS Global Health, and self‐reported Unified Huntington's Disease Rating Scale Total Functional Capacity and Independence Scales). Internal consistency, construct validity, and patient–caregiver proxy consistency were evaluated.
Results: Internal consistency of the three domains and overall HD‐PRO‐TRIAD™ instrument was supported by Cronbach's alpha values ≥0.94. Construct validity was supported by significant correlations between HD‐PRO‐TRIAD™ domain scores and other measures of the same domains (e.g., significant positive correlations between HD‐PRO‐TRIAD™ Anxiety with Neuro‐QOL Anxiety), as well as slightly weaker but still strong correlations with other HRQOL instruments (e.g., HD‐PRO‐TRIAD™ Anxiety and UHDRS Independence; all p less than 0.01). Consistency between patient self‐report and caregiver proxy report was supported by an intra‐class correlation coefficient ≥0.92 for all three domains and the overall instrument.
Discussion: These data indicate that HD‐PRO‐TRIAD™ is a reliable and valid HRQOL instrument that captures the typical triad of HD symptoms.