Validation and calibration of a health-related quality of life questionnaire for patients suffering from slowly progressive neuromuscular disease

• Published in: Annals of physical and rehabilitation medicine 2015-09, Vol.58, p.e126-e126
• Main Authors: Dany, A, Barbe, C., Dr, Wolak-Thierry, A., Dr, Morrone, I., Dr, Dramé, M., Dr, Novella, J.L., Prof, Jolly, D., Prof, Boyer, F., Prof
• Format: Article
• Language: English
• Subjects: Health-related quality of life; Internal Medicine; Item response theory; Neuromuscular disease; Physical Medicine and Rehabilitation; Psychometrics; Validation
• ISSN: 1877-0657; 1877-0665
• DOI: 10.1016/j.rehab.2015.07.302

Introduction Medical care and treatments of patients suffering from slowly-progressive neuromuscular disease (NMD) mainly aim to improve health-related quality of life (HRQOL). To date there is no French HRQOL-measurement tool specifically designed for these patients. Recent works allowed developing a new questionnaire of 26 items named “Quality of Life in Neuromuscular Diseases” (QoL-NMD). It is structured in 3 domains and was constructed using focus groups: Delphi method and exploratory statistical analysis. Our objectives are to validate QoL-NMD using an independent sample and to calibrate the scoring system. Methods The QOL-NMD and a validated questionnaire (WHOQOL-BREF) were administered to 153 patients recruited in 8 tertiary hospitals dedicated to NMD. Confirmatory statistical analysis included methods derived from both Items Response Theory (IRT) and Classical Test Theory. Results Data confirmed the results of the exploratory analysis. The 3 domains of QoL-NMD met IRT assumptions (i.e. unidimensionality, parameter invariance and monotonicity) and showed adequate psychometric properties (Cronbach > 0.7, H > 0.3, test-retest ICC > 0.7). Each domain was calibrated using a parametric IRT model. Comparison to WHOQOL-BREF allowed investigating similarities, discrepancies and putting forward QoL-NMD psychometric superiority. Conclusion This study led to the validation and calibration of a new HRQOL questionnaire specifically designed for NMD patients. It can now be used in various clinical settings. QoL-NMD has been translated and culturally adapted to English but still require a psychometric validation abroad.