A qualitative examination of the content validity of the EQ-5D-5L and EQ-5D-Y-3L in adult and paediatric patients with Duchenne muscular dystrophy

Abstract

Objective: This study examined the content validity of EQ-5D for Chinese patients with DMD. Specifically, it investigated: (1) the content validity of EQ-5D-5L in adult DMD patients and (2) the content validity of EQ-5D-Y-3L (Y-3L) in DMD patients aged 8–15 years. Method: This qualitative study used semi-structured interviews and conducted one-on-one and online, with two groups of individuals with DMD to examine the content validity of the EQ-5D-5L and Y-3L. All participants were recruited from a nationwide DMD patient association. The study included both adult and paediatric DMD patients. Data were analysed using a framework approach. Results: A total of 30 interviews were completed, with 15 for adult patients and 15 for paediatric patients. Overall, EQ-5D-5L and Y-3L covered the most important aspects of HRQoL for DMD patients. However, many adult patients were unclear about the ‘Mobility’ item, suggesting clearer guidance on whether it refers to unaided physical mobility or mobility with assistive devices like wheelchairs. Paediatric patients felt that the three option levels were not enough to accurately describe their mobility. Both adult and paediatric patients noted that essential activities like ‘toileting’ were missing from the self-care section. They also found the examples of usual activities, such as housework, to be unsuitable. Some paediatric patients disliked the examples in Y-3L (headaches and itchiness) and preferred having no examples at all. Regarding mental health questions, both groups struggled to connect their condition with psychological effects. Conclusion: Both EQ-5D-5L and Y-3L showed acceptable content validity; however, our findings indicated the need to refine and optimise these tools to better capture critical HRQoL domains for DMD and potentially other neuromuscular diseases.