A rare disease patient-reported outcome measure: revision and validation of the German version of the Systemic Sclerosis Quality of Life Questionnaire (SScQoL) using the Rasch model

Orphanet Journal of Rare Diseases

Andrew A. Dwyer¹  Peter M. Villiger²  Ulrich A. Walker³  Oliver Distler⁴  Kirsten Hoeper⁵  Kris Denhaerynck⁶  Patrizia Künzler-Heule⁷  Dunja Nicca⁸  Agnes Kocher⁹  Michael Simon^1,10  Anthony C. Redmond^1,11  Mwidimi Ndosi^1,12 

[1] Boston College, Connell School of Nursing, Chestnut Hill, MA, USA;Department of Rheumatology, Immunology and Allergology, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland;Department of Rheumatology, University Hospital Basel, Basel, Switzerland;Department of Rheumatology, University Hospital Zurich, University of Zurich, Zurich, Switzerland;Hannover Medical School, Department, Rheumatology and Immunology, Hannover, Germany;Institute of Nursing Science (INS), Department Public Health (DPH), Faculty of Medicine, University of Basel, Basel, Switzerland;Institute of Nursing Science (INS), Department Public Health (DPH), Faculty of Medicine, University of Basel, Basel, Switzerland;Department of Gastroenterology/Hepatology and Department of Nursing, Cantonal Hospital St. Gallen, St. Gallen, Switzerland;Institute of Nursing Science (INS), Department Public Health (DPH), Faculty of Medicine, University of Basel, Basel, Switzerland;Department of Global and Public Health, Institute for Epidemiology, Biostatistics and Prevention, University of Zurich, Zurich, Switzerland;Institute of Nursing Science (INS), Department Public Health (DPH), Faculty of Medicine, University of Basel, Basel, Switzerland;Department of Rheumatology, Immunology and Allergology, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland;Institute of Nursing Science (INS), Department Public Health (DPH), Faculty of Medicine, University of Basel, Basel, Switzerland;Nursing Research Unit, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland;Leeds Institute of Rheumatic and Musculoskeletal Medicine, University of Leeds, Leeds, UK;NIHR Leeds Biomedical Research Centre, Leeds, UK;School of Health and Social Wellbeing, University of the West of England, Bristol, UK;

关键词: Health-related quality of life;    Item response theory;    Methodology;    Patient-centered care;    Patient reported outcome measures;    Rare diseases;    Rasch analysis;    Rheumatology;    Scleroderma;    Systemic sclerosis;    Validation study;   

DOI  :  10.1186/s13023-021-01944-9

来源: Springer

【 摘 要 】

BackgroundRare disease patient-reported outcome measures (PROMs) require linguistic adaptation to overcome the challenge of geographically dispersed patient populations. Importantly, PROMs such as health-related quality of life (HRQoL) should accurately capture responses to patient-identified concerns. The Systemic Sclerosis Quality of Life Questionnaire (SScQoL) is a 29-item tool validated in six languages. Previous evaluation of the German version revealed problems with dichotomous responses. This study aimed to revise the German SScQoL, extend the response structure, and evaluate content and construct validity, reliability and unidimensionality.MethodsThe instrument validation study involved revising the German SScQoL response structure, cognitive debriefing with patients and validation using Rasch analysis. The revised SScQoL was completed by Swiss-German-speaking patients with SSc within the Swiss MANagement Of Systemic Sclerosis (MANOSS) study. Rasch analysis was employed to test the validity, reliability and unidimensionality of the revised instrument.ResultsBased on cognitive debriefing with patients (n = 6) dichotomous items were extended to a polytomous 4-point response structure. A total of 78 patients completed the revised SScQoL. Initial analysis of the 29 items suggested the scale lacked fit to the model (χ2 = 51.224, df = 29, p = 0.007). Grouping items into five domains resulted in an adequate fit to the Rasch model (χ2 = 5.343, df = 5, p = 0.376) and unidimensionality (proportion of significant independent t tests: 0.045, 95% CI 0.016–0.114). Overall, the scale was well targeted, had high internal consistency (Person Separation Index, PSI = 0.931) and worked consistently in patients with different demographic and clinical characteristics.ConclusionsThe revised German SScQoL has a 4-point response structure and is a valid, reliable measure. Rasch analysis is useful for validating continuous response structure of quality of life measures. Further evaluation of measurement equivalence with other German-speaking cultures is required for multinational comparisons and data pooling.

【 授权许可】

CC BY