title: Further validation and reliability testing of the Rotator Cuff Quality of Life Index (RC-QOL) according to the Consensus-Based Standards for the Selection of Health Measurement Instruments (COSMIN) guidelines.
abstract: BACKGROUND
  The Rotator Cuff Quality of Life Index (RC-QOL) was developed to evaluate quality of life in patients with rotator cuff disorders (RCD). The purpose of this study was to provide additional reliability, validity, and responsiveness testing in accordance with the Consensus-Based Standards for the Selection of Health Measurement Instruments (COSMIN) guidelines.
  
  
  METHODS
  Preliminary patient interviews included 15 patients. Seventy patients (mean age, 58; standard deviation, 9 years) with RCD were evaluated. Methodology testing included internal consistency, test-retest reliability, measurement error, content validity, and construct validity. Responsiveness, interpretability, and generalizability were also analyzed.
  
  
  RESULTS
  The Cronbach α was 0.96 (95% confidence interval, 0.89-0.99; range, 0.72-0.94). The intraclass correlation coefficient for the RC-QOL was 0.87 (95% confidence interval, 0.79-0.85; range, 0.77-0.88). The standard error of measurement was 8 (range, 7-13). The smallest detectable change was 3 (range, 2-4). Content validity was confirmed through standardized patient interviews. All a priori hypotheses were confirmed. No floor or ceiling effects were present. The minimally clinical important difference ranged between 7 and 14 points. The study met the COSMIN criteria for interpretability and generalizability.
  
  
  CONCLUSIONS
  The RC-QOL is a reliable and valid measure of health-related quality of life in patients with chronic RCD. The results of this study added to the methodologic quality assessment of the RC-QOL, completing 7 of 10 COSMIN criteria.
authors.affiliation: Department of Health and Physical Education, Faculty of Health, Community, and Education, Mount Royal University, Calgary, AB, Canada. Electronic address: beubank@mtroyal.ca.
authors.forename: Breda H
authors.initials: BH
authors.lastname: Eubank
authors.affiliation: Sport Medicine Centre, Faculty of Kinesiology, University of Calgary, Calgary, AB, Canada.
authors.forename: Nicholas G
authors.initials: NG
authors.lastname: Mohtadi
authors.affiliation: Department of Health and Physical Education, Faculty of Health, Community, and Education, Mount Royal University, Calgary, AB, Canada.
authors.forename: Mark R
authors.initials: MR
authors.lastname: Lafave
authors.affiliation: Sport Medicine Centre, Faculty of Kinesiology, University of Calgary, Calgary, AB, Canada.
authors.forename: J Preston
authors.initials: JP
authors.lastname: Wiley
authors.affiliation: Department of Economics, Faculty of Arts, University of New Brunswick, Fredericton, NB, Canada.
authors.forename: J C Herbert
authors.initials: JC
authors.lastname: Emery
mesh_terms: D000328:Adult; D000368:Aged; D000416:Alberta; D001265:Athletic Injuries / Q000523:psychology; D019985:Benchmarking; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D017410:Practice Guidelines as Topic; D011446:Prospective Studies; D011594:Psychometrics; D011788:Quality of Life; D015203:Reproducibility of Results; D000070636:Rotator Cuff Injuries / Q000523:psychology*; D011795:Surveys and Questionnaires
keywords: psychometric assessment; quality of life; reliability; rotator cuff; shoulder; validity