caa a22 4500 606177965 CHVBK 20210128100754.0 cr unu---uuuuu 210128e20150101xx s 000 0 eng 10.1007/s11136-013-0570-y doi (NATIONALLICENCE)springer-10.1007/s11136-013-0570-y The St George's Respiratory Questionnaire revisited: a psychometric evaluation [Elektronische Daten] [Muirne Paap, Danny Brouwer, Cees Glas, Evelyn Monninkhof, Benjamin Forstreuter, Marcel Pieterse, Job van der Palen] Purpose: The St George's Respiratory Questionnaire (SGRQ) has clearly acquired the status of legacy questionnaire for measuring health-related quality of life in patients with chronic obstructive pulmonary disease (COPD). The main aim of this study was to assess the underlying dimensionality of the SGRQ and to investigate the added value of the empirical weights used to calculate total scores. Methods: The official Dutch translation of the SGRQ was completed by 444 COPD patients participating in two clinical studies. These data were used for secondary data analysis in this study. Three complementary statistical methods were used to assess dimensionality: Mokken scale analysis (MSA), parametric multidimensional item response theory (IRT) and bifactor analysis. Additionally, the original SGRQ weighting procedure was compared to IRT-based weighting. Results: The results of the MSA and multidimensional item response theory (MIRT) pointed toward a unidimensional structure. The bifactor analyses indicated that there was a strong general factor, but the group factors did have additional value. Nineteen items performed poorly in the MSA, MIRT analysis or both. Shortening the scale from 50 to 31 items did not negatively impact measurement precision. SGRQ total score and IRT-derived scores correlated strongly, 0.90 for the one-parameter model and 0.99 for the two-parameter model. Conclusion: The SGRQ contains some multidimensionality, but an abbreviated version can be used as a unidimensional tool in patients with COPD. Subscale scores should be used with care. SGRQ total scores correlated highly with IRT-based scores, and thus, the weighting methods may be used interchangeably to calculate total scores. Springer Science+Business Media Dordrecht, 2013 Multidimensional item response theory nationallicence Bifactor analysis nationallicence SGRQ nationallicence Mokken scale analysis nationallicence COPD nationallicence 1PL : One-parameter logistic nationallicence 2PL : Two-parameter logistic nationallicence CFI : Comparative fit index nationallicence COPD : Chronic obstructive pulmonary disease nationallicence ECV : Explained common variance nationallicence FA : Factor analysis nationallicence GA : Genetic algorithm nationallicence GPCM : Generalized partial credit model nationallicence HRQoL : Health-related quality of life nationallicence HS : Health status nationallicence IRT : Item response theory nationallicence MIRT : Multidimensional item response theory nationallicence MSA : Mokken scale analysis nationallicence PCA : Principal component analysis nationallicence SGRQ : St George's Respiratory Questionnaire nationallicence SGRQ-C : COPD-specific version of the St George's Respiratory Questionnaire nationallicence TLI : Tucker-Lewis index nationallicence QoL : Quality of life nationallicence RSMEA : Root mean square error of approximation nationallicence VAS : Visual analogue scale nationallicence Paap Muirne Department of Research Methodology, Measurement, and Data-Analysis, Behavioral Sciences, University of Twente, P.O. Box 217, 7500, Enschede, AE, The Netherlands aut Brouwer Danny Department of Psychometrics and Statistics, Behavioral Sciences, University of Groningen, Groningen, The Netherlands aut Glas Cees Department of Research Methodology, Measurement, and Data-Analysis, Behavioral Sciences, University of Twente, P.O. Box 217, 7500, Enschede, AE, The Netherlands aut Monninkhof Evelyn Julius Center for Health and Primary Care, University Medical Center Utrecht, Utrecht, The Netherlands aut Forstreuter Benjamin University of Twente, Enschede, The Netherlands aut Pieterse Marcel Department of Psychology, Health and Technology, Behavioral Sciences, University of Twente, Enschede, The Netherlands aut van der Palen Job Department of Research Methodology, Measurement, and Data-Analysis, Behavioral Sciences, University of Twente, P.O. Box 217, 7500, Enschede, AE, The Netherlands aut Quality of Life Research Springer International Publishing 24/1(2015-01-01), 67-79 0962-9343 24:1<67 2015 24 11136 https://doi.org/10.1007/s11136-013-0570-y text/html Onlinezugriff via DOI BK010053 XK010053 XK010000 Metadata rights reserved Springer special CC-BY-NC licence nationallicence 1 research-article jats NATIONALLICENCE NATIONALLICENCE NL-springer NATIONALLICENCE 856 40 https://doi.org/10.1007/s11136-013-0570-y text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Paap Muirne Department of Research Methodology, Measurement, and Data-Analysis, Behavioral Sciences, University of Twente, P.O. Box 217, 7500, Enschede, AE, The Netherlands aut NATIONALLICENCE 700 1- Brouwer Danny Department of Psychometrics and Statistics, Behavioral Sciences, University of Groningen, Groningen, The Netherlands aut NATIONALLICENCE 700 1- Glas Cees Department of Research Methodology, Measurement, and Data-Analysis, Behavioral Sciences, University of Twente, P.O. Box 217, 7500, Enschede, AE, The Netherlands aut NATIONALLICENCE 700 1- Monninkhof Evelyn Julius Center for Health and Primary Care, University Medical Center Utrecht, Utrecht, The Netherlands aut NATIONALLICENCE 700 1- Forstreuter Benjamin University of Twente, Enschede, The Netherlands aut NATIONALLICENCE 700 1- Pieterse Marcel Department of Psychology, Health and Technology, Behavioral Sciences, University of Twente, Enschede, The Netherlands aut NATIONALLICENCE 700 1- van der Palen Job Department of Research Methodology, Measurement, and Data-Analysis, Behavioral Sciences, University of Twente, P.O. Box 217, 7500, Enschede, AE, The Netherlands aut NATIONALLICENCE 773 0- Quality of Life Research Springer International Publishing 24/1(2015-01-01), 67-79 0962-9343 24:1<67 2015 24 11136