Title Standard error of measurement and smallest detectable change of the Sarcopenia Quality of Life (SarQoL) questionnaire: an analysis of subjects from 9 validation studies /
Authors Geerinck, Anton ; Alekna, Vidmantas ; Beaudart, Charlotte ; Bautmans, Ivan ; Cooper, Cyrus ; De Souza Orlandi, Fabiana ; Konstantynowicz, Jerzy ; Montero-Errasquin, Beatriz ; Topinkova, Eva ; Tsekoura, Maria ; Reginster, Jean-Yves ; Bruyere, Olivier
DOI 10.1371/journal.pone.0216065
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Is Part of PlosOne.. San Francisko : Public Library of Science. 2019, vol. 14, no. 4, art. no. e0216065, p. 1-13.. ISSN 1932-6203
Keywords [eng] standard error of measurement ; smallest detectable change ; SarQoL ; sarcopenia ; measurement error ; reliability
Abstract [eng] Objectives The Sarcopenia Quality of Life (SarQoL) questionnaire, a sarcopenia-specific patientreported outcome measure, evaluates quality of life with 55 items. It produces 7 domain scores and 1 overall quality of life score, all between 0 and 100 points. This study aims to contribute to the interpretation of the SarQoL scores by calculating the standard error of measurement (SEM) and smallest detectable change (SDC) in a sample of subjects from 9 studies. Methods Subjects from 9 studies (conducted in Belgium, Brazil, Czech Republic, England, Greece, Lithuania, Poland and Spain) were included. The SEM, a measure of the error in the scores that is not due to true changes, was calculated by dividing the standard deviation of the difference between test and retest scores (SDdiff) by p 2. The SDC, defined as change beyond measurement error, was calculated by multiplying SDdiff by 1.96. Bland-Altman plots were assessed for the presence of systematic errors. Results A total of 278 sarcopenic subjects, aged 77.67 ± 7.64 years and 61.5% women, were included. The SEM for the overall SarQoL score ranged from 0.18 to 4.20 points for the individual studies, and was 2.65 points when all subjects were analyzed together. The SDC for the overall score ranged from 0.49 to 11.65 points for the individual studies, and was 7.35 points for all subjects. The Bland-Altman plots revealed no systematic errors in the questionnaire. Conclusion This study shows that, for individual subjects, a change in overall quality of life of at leist 7.35 points (on a scale from 0 to 100) would have to be observed to confirm that a true change, beyond measurement error, has occurred. It also demonstrated that the SarQoL questionnaire is a precise instrument, with the observed cores within less than 3 points of the theoretical “true score”.
Published San Francisko : Public Library of Science
Type Journal article
Language English
Publication date 2019
CC license CC license description