Validity and reliability of the Persian versions of WOMAC Osteoarthritis Index and Lequesne Algofunctional Index

The WOMAC Osteoarthritis Index and Lequesne Algofunctional Index have not been translated and validated for Iranian patients with osteoarthritis (OA) of the knee or hip. The aim of this study was to validate the Persian form of WOMAC OA Index and Lequesne Algofunctional Index and to assess their test-retest reliability and convergent validity. Forward/backward translations and consensus panels were conducted to obtain the Persian versions of WOMAC OA Index and Lequesne Algofunctional Index. A non-probability sample of 116 patients with knee/hip osteoarthritis was asked to complete the WOMAC OA Index and Lequesne Algofunctional Index as well as Medical Outcomes Study-20-Item Short Form (SF-20) questionnaires, a visual analogue scales (VAS) of pain and demographic information form. Internal consistency (using Cronbach's alpha) and convergent validity (by examining the Pearson's correlation coefficients) were evaluated to determine the psychometric properties of the questionnaires. In order to evaluate test-retest reliability, 20 randomly selected patients completed the questionnaires, on a second occasion, 7-10 days later. Cronbach's alpha coefficients and intraclass correlation coefficients for the WOMAC OA Index and Algofunctional Index subscales ranged from 0.63 to 0.94 and from 0.53 to 0.96, respectively. Statistically significant correlations were found between WOMAC OA Index, Algofunctional Index and SF-20 subscales and VAS for pain. The Persian version of WOMAC demonstrated a more acceptable validity, internal consistency and reliability compared with the Lequesne Algofunctional Index. However, both indices are valid and reliable instruments for evaluating the OA severity of knee/hip in Iran.