To assess health-related quality of life (HRQL) in patients suffering from slowly progressive neuromuscular disease (NMD) using item response theory (IRT), a questionnaire called QoL-NMD was developed. It is composed of two general items and 24 items classified in three domains: (1) “Impact of Physical Symptoms,” (2) “Self-perception” and (3) “Activities and Social Participation.” Each domain has good psychometric properties (Cronbach’s alpha > 0.77, test-retest ICC > 0.81, Loevinger’s H > 0.41) and meets IRT assumptions. We constructed a questionnaire named which is Comparison with the validated questionnaire, WHOQOL-BREF, enabled assessing similarities and discrepancies with a generic questionnaire. The QoL-NMD is short enough to be used in clinical practice (26 items). The next steps will be to validate QoL-NMD by re-assessing psychometrics in an independent sample of patients and calibrate the IRT scoring system.
