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.