Translation, cross-cultural adaptation and validation of the traditional Chinese intermittent and constant osteoarthritis pain (ICOAP) questionnaire for knee osteoarthritis.

OBJECTIVES: To translate and culturally adapt the Intermittent and Constant Osteoarthritis and Pain (ICOAP) measure to a traditional Chinese version, and to study its psychometric properties in patients with knee osteoarthritis (KOA). METHOD: The ICOAP was translated and cross-culturally adapted into traditional Chinese according to the recommended international guidelines. A total of 110 participants with KOA in Hong Kong were invited to complete the traditional Chinese ICOAP (tChICOAP), the Chinese Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) pain subscale and the Chinese Short form of Health Survey (SF-12v2). Psychometric evaluations included content validity, construct validity, internal consistency and test and retest reliability. RESULTS: All participants completed the tChICOAP questionnaire without missing items. The content validity index of all items ranged from 80% to 100%. The tChICOAP total pain and subscale scores had excellent internal consistency with Cronbach's alpha value (0.902-0.948) and good corrected item-total subscale correlations. It had high test and retest reliability (intra-class correlations 0.924-0.960). The tChICOAP constant, intermittent and total pain scores correlate strongly with the WOMAC pain subscale (r=0.671, 0.678 and 0.707, respectively, p<0.001). The tChICOAP intermittent and total scores correlate strongly with SF-12v2 physical component score (r=-0.590 and -0.558, respectively, p<0.001). CONCLUSIONS: The tChICOAP is a reliable and valid instrument to measure the pain experience of Chinese patients with KOA.