Health State Utility Scores for DMD-Related Impairment Need to Better Reflect Patient Input

To have a more clear understanding of patients’ symptoms of Duchenne muscular dystrophy (DMD) and their impact on quality of life (QOL), a team of investigators evaluated health state utilities using patient-reported outcomes and published their findings in Journal of Patient-Reported Outcomes.¹

Health state utility scores range from negative values, or a state considered worse than death, to 0 (indicates death) to 1 (indicates full health).² For this analysis, these data were collected using the Health Utilities Index (HUI) and its 2 complementary systems, the HUI mark 2 (HUI2) and mark 3 (HUI3), and the EQ-ED-FL, which evaluates mobility, self-care, usual activities, pain/discomfort, and anxiety/depression from “not a problem” to “extreme problem.”³ Patients were classified by health status into 1 of 3 groups: early ambulatory (17.5%), late ambulatory (12.7%), and nonambulatory (early and late; 69.8%).

An informational email meant to recruit study participants (N = 63) was sent to mailing list participants of Parent Project Muscular Dystrophy, a US-based advocacy group. The mean (SD) patient age was 19.8 (16.1) years, and most had mildly (34.9%) or moderately (28.6%) impaired upper limb function, did not require ventilation (47.6%) or required it only at night (38.1%), and had asymptomatic cardiomyopathy (41.3%) or did not have identified cardiomyopathy (44.4%). All participants were male patients.

Hands of a disabled person with muscular dystrophy holding a ventilator | Image Credit: ins - stock.adobe.com

“Published utilities tend to be derived from small samples for a limited number of health states and are often based on caregiver-reported patient health status,” the study authors wrote. “This study estimated utility values for varied clinical and functional health states in DMD, based on patient-reported health status.”

Among the early ambulatory cohort (n = 11), the highest mean utility value was 0.89 (0.13) seen for the HUI2, which considers sensation (vision, hearing, and speech), mobility, emotion, cognition, self-care, pain, and fertility. On the HUI3, which considers vision, hearing, speech, ambulation, dexterity, emotion, cognition, and pain, the utility value was 0.81 (0.22), and for the EQ-5D-5L, 0.79 (0.20).

The late ambulatory participants (n = 8) had a mean HUI2 utility value of 0.71 (0.24), a HUI3 utility value of 0.64 (0.32), and an EQ-5D-5L of 0.64 (0.30).

For the patients in the early nonambulatory group (n = 21), the values were 0.49 (0.12), 0.22 (0.14), and 0.31 (0.13), for the HUI2, HUI3, and EQ-5D-5L, respectively, and in the late nonambulatory group (n = 23), 0.47 (0.10), 0.15 (0.15), and 0.22 (0.15). As expected, the utility values were lowest in this last group.

The authors noted that for the HUI2, mobility, self-care, sensation, and pain were shown to be affected the most. For mobility, the more lower and upper limb function declined, the worse the score. For self-care, whereas ambulatory participants did not report any impairment, mildly impaired upper limb function and loss of that function, nighttime/daytime ventilation, and symptomatic cardiomyopathy indicated severe impairment among nonambulatory participants. Sensation and pain were not as affected but trended worse in the patients who were nonambulatory.

For the HUI3, ambulation, dexterity, pain, emotion, and vision and cognition were reported most affected, and scores again worsened with decreasing lower and upper limb function. Dexterity was not very impaired in the ambulatory group; however, moderate impairment to upper limb function and loss of lower limb function correlated with greater impact on the overall health of the patient. Pain and emotion effects fluctuated, “rather than increasing consistently with increasing functional impairment in DMD,” the authors wrote.

On the EQ-5D-5L, mobility, self-care, usually activities, pain/discomfort, and anxiety/depression were reported to be most affected. Nonambulatory participants with any upper limb impairment had uniformly poor mobility and self-care scores vs ambulatory/transitional participants whose scores only demonstrated mild/moderate impairment. This latter group had similar results for usual activities, but increasing disease severity was linked to increasing impairment. Health utility scores for pain and discomfort were consistent across the 3 classified health statuses, but those for anxiety/depression varied and did not match up with an increased health state severity.

“This study documented the effects of disease progression and health-related QOL impact on utility in DMD, with lower utility values recorded for more severe health states,” the authors wrote. “Patients have unique insights on living with their health condition, and caregivers may not necessarily understand the exact extent of the [health-related QOL] impact on their child.”

To continue gaining a greater understanding of the patient perspective in DMD, future studies will need to cover more patients, continue to investigate how DMD-related utility changes throughout the disease course, and evaluate what affects utility scores, they added.

References

1. Audhya FI, Szabo SM, Bever A, et al. Estimating health state utilities in Duchenne muscular dystrophy using the health utilities index and EQ-5D-5L. J Patient Rep Outcomes. 2023;7(1):132. doi:10.1186/s41687-023-00671-y
2. Wolowacz SE, Briggs A, Belozeroff V, et al. Estimating health-state utility for economic models in clinical studies: an ISPOR Good Research Practices Task Force report. Value Health. 2016;19(6):704-719. doi:10.1016/j.jval.2016.06.001
3. EQ-5D-5L. EuroQol. Updated November 30, 2021. Accessed January 10, 2024. https://euroqol.org/eq-5d-instruments/eq-5d-5l-about/#:~:text=Each%20dimension%20has%205%20levels,each%20of%20the%20five%20dimensions