Psychometric Validation of the BODY-Q in Danish Patients Undergoing Weight Loss and Body Contouring Surgery

Background A well-developed patient-reported outcome instrument is needed for use in Danish bariatric and body contouring patients. The BODY-Q is designed to measure changes in important patient outcomes over the entire patient journey, from obesity to post-body contouring surgery. The current study aims to psychometrically validate the BODY-Q for use in Danish patients. Methods The process consisted of 3 stages: translation and linguistic validation, field-test, and data analysis. The translation was performed in accordance with the International Society for Pharmacoeconomics and Outcomes Research and World Health Organization guidelines, and field-test data were collected in 4 departments in 2 different hospitals. Field-test data were analyzed using Rasch Measurement Theory. Results A total of 495 patients completed the Danish BODY-Q field-test 1-4 times, leading to a total of 681 assessments with an overall response rate at 76%. Cronbach α values were ≥ 0.90, and person separation index values were in general high. The Rasch Measurement Theory analysis provided broad support for the reliability and validity of the Danish version of the BODY-Q scales. Item fit was outside the criteria for 34 of 138 items, and of these, 21 had a significant chi-square P value after Bonferroni adjustment. Most items (128 of 138) had ordered thresholds, indicating that response options worked as intended. Conclusion The Danish version of the BODY-Q is a reliable and valid patient-reported outcome instrument for use in Danish bariatric and body contouring patients.