Validation of a Persian-version of Knee injury and Osteoarthritis Outcome Score (KOOS) in Iranians with knee injuries

Objective: To adapt culturally and validate Persian-version of the Knee injury and Osteoarthritis Outcome Score (KOOS) in a sample of Iranians with knee injuries. Methods: Cultural adaptation included providing of forward and backward translations, quality rating and pilot testing. A sample of 147 patients with anterior cruciate ligament (ACL), meniscus and combined (ACL and meniscus) injuries was asked to complete two questionnaires including the KOOS and Short-Form 36 Health Survey (SF-36). The KOOS was readministered to 54 patients 6-8 days after the first visit. Test-retest reliability and internal consistency were assessed, using Intraclass Correlation Coefficient (ICC) and Cronbach's alpha, respectively. Dimensionality was assessed, using item-scale correlation after correction for overlap and construct validity, using a priori hypothesized correlations with the SF-36. Results: All patients found the Persian-version of the KOOS to be clear and unambiguous in pilot testing. Minimum ICC level of 0.70 was exceeded by all subscales with the exception of Sport and Recreation (Sport/Rec) subscale. Minimum Cronbach's alpha level of 0.70 was exceeded by all subscales with the exception of Symptoms and Knee-related Quality of Life (OoL). Minimum Spearman correlation coefficient of 0.40 for each item-scale was exceeded by 34 items. All priori hypotheses were supported by the presence of higher correlations between similar constructs than between dissimilar constructs of the KOOS and SF-36. Conclusion: The Persian-version of the KOOS is a culturally-adapted, reliable and valid outcome measure to be used in Iranian patients with knee injuries, with its psychometric properties in agreement with the original versions. (C) 2008 Osteoarthritis Research Society International. Published by Elsevier Ltd. All rights reserved.