Cross-cultural adaptation and validation of Korean Western Ontario and McMaster Universities (WOMAC) and Lequesne osteoarthritis indices for clinical research

Objective: Our aims were to translate WOMAC and Lequesne osteoarthritis (OA) indices into Korean (KWOMAC, KLequesne) and confirm their reliability, validity, and responsiveness.

Design: The WOMAC and Lequesne indices were translated into Korean by three translators and translated back into English by three different translators. Fifty consecutive patients with OA were asked to rate the comprehensibility of the questions on a 4-point scale. The comprehensibility (responding with 'good' and 'very good') ranged from 78% to 99%. Test-retest was performed in another 47 patients with knee OA. The final 53 patients with knee OA, within the context of a clinical trial of two non-steroidal antiinflammatory drugs for 4 weeks, were studied to assess the internal consistency, construct validity, and responsiveness of the Korean versions.

Results: The test-retest reliability of the KWOMAC 3 subscales and the KLequesne yielded intraclass correlation coefficients of 0.79-0.89 and 0.87. The Cronbach standardized alphas were 0.81-0.96 and 0.75, respectively. For the construct validity, the correlation coefficients of both the KWOMAC subscales and the KLequesne with patient pain assessment and patient global assessment were between 0.30 and 0.70 and the KWOMAC subscales correlated with the KLequesne (0.41-0.55). For responsiveness, the KWOMAC and KLequesne scores significantly improved by 4-week post-treatment compared with pre-treatment; effect size values were between 0.41 and 0.69 for the KWOMAC subscales and 0.70 for the KLequesne; and the relative efficiency values of the KWOMAC subscales vs the KLequesne were between 0.87 and 0.90.

Conclusions: The reliability, validity, and responsiveness of the KWOMAC and the KLequesne are confirmed.