OBJECTIVES : The Pediatric Quality of Life (PedsQL) Generic Core Scale v4.0 (GC) and the Neuromuscular Module v3.0 (NMM) are among the most commonly used instruments for measuring health-related quality of life (HRQoL) in Duchenne Muscular Dystrophy (DMD). This study examines their psychometric properties to determine their suitability for assessing patient-perceived treatment benefit in DMD.

METHODS : Data derive from a Phase IIb eteplirsen trial (NCT01396239). Twelve ambulatory boys with DMD and their parents completed the PedsQL GC and NMM. Baseline item-level performance (floor/ceiling effects), internal consistency reliability (ICR; Cronbach’s alpha), inter-item correlations (redundant items), and inter-rater (child self-report [CSR] vs. parent proxy-report [PPR]) reliability (IRR; intra-class correlation [ICC]) were examined.

RESULTS : With the exception of one item in the PedsQL GC CSR Physical Functioning (PF) domain, all other items across domains exhibited a ceiling effect (range: 16.7%-83.3%). Excluding one item in the PedsQL GC PPR PF and Social Functioning domains, the proportion of respondents scoring at ceiling ranged from 8.3%-58.3% across all other items. All items across the PedsQL NMM CSR and PPR domains had a proportion of respondents scoring at ceiling (range: 8.3%-100% for both). Acceptable ICR was demonstrated on the PedsQL GC CSR PF domain (0.81), the PedsQL GC PPR Emotional Functioning (0.84) and School Functioning (0.76) domains, and the PedsQL NMM PPR About My Neuromuscular Disease (0.89) domain; all other domain-specific ICRs fell outside the range of acceptability. IRR for the PedsQL GC PF domain and the PedsQL NMM Communication domain was acceptable (ICC=0.80 and 0.79, respectively); all other domain-specific IRRs varied from negligible (~0) to low (<0.25). Inter-item correlations demonstrated considerable item redundancy within domains.

CONCLUSIONS : This study shows that the PedsQL GC and NMM may be suboptimal measures for assessing HRQoL and treatment benefit in ambulatory boys with DMD.