Development of a new quality of life measure for Duchenne muscular dystrophy using mixed methods

Objective Based on concerns over existing patient reported outcome measures (PROMs) for assessing quality of life (QoL) in Duchenne muscular dystrophy (DMD), we describe the mixed methods development of a new QoL PROM for use in boys and men with DMD: the DMD-QoL.

Methods The DMD-QoL was developed in 3 stages. First, draft items were generated from 18 semi-structured qualitative interviews with boys and men with DMD, analysed using framework analysis. Second, cognitive debriefing interviews with patients (n = 10), clinicians (n = 8), and patients' parents (n = 10) were undertaken and a reduced item set selected and refined. Third, psychometric data on the draft items from a cross-sectional online survey (n = 102), and stakeholder input from patients and patients' parents, was used to produce the final questionnaire. Patient and public involvement and engagement was embedded throughout the process.

Results From an initial draft of 47 items, a revised set of 27 items was produced at stage 2, and this set was further refined at stage 3 to generate the DMD-QoL, a 14-item QoL PROM. The 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. The final measure showed good psychometric properties.

Conclusions The DMD-QoL is a new 14-item QoL PROM for boys and men with DMD, with demonstrable content and face validity.