Cross-cultural validation of the ICOAP and physical function short forms of the HOOS and KOOS in a multi-country study of patients with hip and knee osteoarthritis

Objective To evaluate the internal consistency and construct validity of the Physical Function short-forms for the Hip and Knee Injury Osteoarthritis Outcome Scores (HOOS-PS/KOOS-PS) and the Intermittent and Constant Osteoarthritis Pain (ICOAP) in a nine country study of patients consulting for total hip or knee replacement (THR or TKR). Methods Patients completed HOOS-PS or KOOS-PS, ICOAP and Western Ontario and McMaster Universities' Osteoarthritis Index (WOMAC) pain and physical function subscales at their consultation visit. Internal consistency was calculated using Cronbach's alpha. The association of HOOS-PS/KOOS-PS and ICOAP with WOMAC pain and function subscales was calculated with Spearman correlation coefficients with 95% confidence intervals. Results HOOS-PS/KOOS-PS and ICOAP demonstrated high internal consistency across countries (alpha 0.75–0.96 (hip) and 0.76–0.95 (knee)). Both HOOS-PS and KOOS-PS demonstrated high correlations (0.76–0.90 and 0.75–0.91, respectively) with WOMAC function in all countries. ICOAP exhibited moderate to high correlations with WOMAC pain and function subscales (0.53–0.84 (hip) and 0.43–0.84 (knee)). Conclusion The psychometric properties of the HOOS-PS/KOOS-PS, and ICOAP were maintained across all countries.