Patient-reported outcome measures assess quality of life in Duchenne muscular dystrophy

Researchers developed a new 14-item patient-reported outcome measure for assessing quality of life in men and boys with Duchenne muscular dystrophy, according to results published in Neurology.

“Studies assessing health-related quality of life (QoL) in people with Duchenne muscular dystrophy (DMD) suggest it is impaired compared to the general population. However, the ability of existing measures to adequately capture QoL in DMD has been questioned, with it posited that there is no optimal measure available,” Philip A. Powell, PhD, a research fellow and chartered psychologist in the School of Health and Related Research at the University of Sheffield, and colleagues wrote. “Our primary objective was to develop a new QoL patient-reported outcome measures (PROM) for use in boys and men with DMD (aged 7 years and older) and to assess its preliminary psychometric properties.”

In developing the DMD-QoL, researchers first generated a draft of 43 items informed by 18 semi-structured qualitative interviews with boys and men with DMD. To assess the content relevance, comprehensiveness and comprehensibility of the initially drafted items, researchers conducted cognitive debriefing interviews with 10 patients with DMD, 10 parents of patients with DMD (aged 30 years to 59 years; 70% mothers) and 8 clinicians (aged 40 years to 59 years; 75% women); this yielded a reduced set of 27 items. A cross-sectional online survey analyzed psychometric data from 102 patients with DMD or participants responding on behalf of someone with a diagnosis of DMD. Stakeholder input further refined the final 14-item questionnaire.

The 14-item DMD-QoL “is designed for use from 7 years of age by proxy report and from 10 years of age by self or proxy report,” according to the researchers, who also noted that the final measure they developed demonstrated good psychometric properties. It uses a hierarchical 3-domain structure with physical, social and psychological subdomains, as well as a superordinate QoL factor.

Strengths of the measure include the creation of a “rigorous” patient-reported outcome measure for a rare condition and a high degree of patient and public involvement and engagement and input from clinicians, as well as “the inclusion of iterative qualitative work,” which led to a patient-reported outcome measure with “evident content validity,” according to the researchers. The ability to use this measure across the life span will allow clinicians to compare differences in QoL across stages of DMD progression with a common scale. It is also “intentionally short” to reduce patient burden, which may be high in DMD, according to the study results.

In spite of these strengths, however, there are “several apparent limitations” with this measure in its current form, the researchers noted, including the fact that it may not be “exhaustive.” Additionally, the researchers considered certain aspects of QoL, such as sexual relationships and end-of-life issues, “inappropriate to be included in a questionnaire to be used from childhood.” Powell and colleagues suggested that future work could include additional questions for adults.

“Initial analyses suggest DMD-QoL performs well in people with DMD (and their caregivers). However, taking into account the aforementioned limitations, the DMD-QoL requires further independent validation and also needs to be compared for its performance against alternative QoL instruments,” the researchers wrote. “In the immediate next stage of its development, the measure will be valued to generate a preference-based measure that can be used to generate quality adjusted life years to inform resource allocation decisions within health technology assessments.”