Cross-cultural adaptation and validation of Singapore English and Chinese versions of the Lequesne Algofunctional Index of knee in Asians with knee osteoarthritis in Singapore

OBJECTIVE: To cross-culturally adapt and validate Singapore English and Chinese versions of the Lequesne Algofunctional Index of knee in patients with knee osteoarthritis (OA) in Singapore. METHODS: Singapore English and Chinese versions were cross-culturally adapted from the source English version following standard guideline (including cognitive debriefing). Patients were asked to complete an identical, pretested questionnaire containing the Lequesne index, Short Form 36 Health Survey (SF-36), and EQ-5D twice within 6 days. Reliability was assessed using Cronbach's alpha and intraclass correlation coefficients (ICC). Dimensionality was assessed by principal component factor analysis. Construct validity was tested by item-to-scale correlations and 12 and six a priori hypotheses for convergent and divergent construct validities, respectively. RESULTS: Singapore English and Chinese Lequesne indices were well accepted by patients in pilot testing and were therefore administered to a consecutive sample of 127 English- and 131 Chinese-speaking Singaporeans with knee OA. Acceptable internal consistency was observed for activities of daily living and the global index (alpha=0.72-0.82), and the good test-retest reliability for all scales in both versions (ICC=0.66-0.94). Expected item-to-scale correlations were presented only in activities of daily living in both versions. Factor analysis yielded two factors for both versions. Convergent and divergent construct validities were supported by the presence of hypothesized correlations between the Lequesne index and SF-36 and EQ-5D scales. CONCLUSION: Both versions of the Lequesne index demonstrated acceptable reliability and validity among multiethnic Asian patients with knee OA, which suggests that it could be used as a global index in the health-related quality of life (HRQoL) measurements in Singapore and possibly other Asian countries.