SC3 The Drivers of Health State Utilities in Duchenne Muscular Dystrophy (DMD): A Study Using the Health Utilities Index Mark 3 (HUI3)

DMD is a rare neurodegenerative disease with profound functional loss that dramatically affects health-related quality-of-life (HRQoL). Limited data on health state utilities in DMD exist, and the drivers of utility in DMD are not well understood. This study assessed which HRQoL attributes most affect health state utilities among patients with DMD. Family members serving as proxy respondents for ambulatory boys with DMD, recruited under NCT01254019 (provided by BioMarin Pharmaceuticals Inc), completed the HUI3 measure; only placebo-treated boys were included. Level of impairment (ranging from 1 [no impairment] to 5 or 6 [severe impairment] on each of the eight HUI3 attributes was reported. Mean (standard deviation [SD]) HUI3 attribute levels and utility scores at baseline were computed. The proportion of patients with moderate or severe impairments in each attribute was calculated and the percent of variability in overall HUI3 utility scores explained by each attribute estimated by linear regression. At baseline, the mean (range) age was 8.0 (5-16; n=61) years and mean (SD) HUI3 utility was 0.82 (0.19). Mean (SD) attribute levels were: vision, 1.03 (0.18); hearing, 1.00 (0.00); speech, 1.08 (0.28); ambulation, 1.68 (0.91); dexterity, 1.22 (0.76); emotion, 1.12 (0.32); cognition, 1.37 (0.94); and pain, 1.77 (0.72). Moderate or severe impairments were most often reported for pain (17%), ambulation (13%), cognition (7%), and dexterity (5%). The attributes explaining the largest proportions of variability in overall HUI3 utility scores were ambulation (48%), cognition (33%), pain (30%), and dexterity (26%); together explaining 96% of variability. In this sample of ambulatory boys with DMD, the largest impairments in the aspects of HRQoL measured by the HUI3 were in ambulation, pain, cognition and dexterity; and these attributes explained almost all observed variability in baseline utility scores. These data shed further light on the drivers of health state utility in DMD.