Psychometric validation of the Copenhagen Hip and Groin Outcome Score (HAGOS) and Oxford Hip Score (OHS) in patients with hip-abductor tendon pathology

Objective: Validated patient-reported outcome measures for patients with hip-abductor tendon pathology are lacking. Recent studies indicate that the Copenhagen Hip and Groin Outcome Score (HAGOS), in the original or the revised scoring format, and the Oxford Hip Score (OHS) may be relevant for use in patients with hip-abductor tendon pathology. The objective of this study was to assess the validity of the Danish version of the HAGOS, the revised HAGOS, and the OHS psychometrically in patients with hip-abductor tendon pathology. This involved the six subscales in the original and the revised version of HAGOS, the standard one-factor scoring of the OHS and the two-factor scoring of the OHS. Methods: We included individual responses to HAGOS and OHS from 210 patients with hip-abductor tendon pathology (17 men; 193 women; median age 56 years, range 18-91, IQR 48-65). Overall fit, model fit, individual item fit and measurement invariance were examined using confirmatory factor analysis (CFA) and item response theory. Results: CFA rejected psychometric validity of three original HAGOS subscales (symptoms, pain, physical function in sport and recreation) (p<0.0001) and the OHS (p<0.0001), whereas the revised scoring format for HAGOS subscales fit adequately. Results indicate a notable discrepancy between observed and expected scores on OHS item 10 in the patient group. Conclusion: The original HAGOS and OHS are not psychometrically valid, but the revised HAGOS scoring format is an appropriate PROM for patients with hip-abductor tendon pathology. The OHS would need slight adjustment before being used in patients with hip-abductor tendon pathology.