Reliability of the Kannada Version of the Knee Injury and Osteoarthritis Outcome Score: A Cross-sectional Study

Abstract

Introduction: The Knee Injury and Osteoarthritis Outcome Score (KOOS) is a valid and reliable tool for assessing knee injury and osteoarthritis (OA). It has been cross-culturally adapted into several Indian languages. However, the reliability of the Kannada translation of the KOOS scale has not been established. Aim: The aim of this study was to confirm the reliability of the Kannada translation of the KOOS scale and to assess the interrater and test-retest reliability of the culturally adapted KOOS outcome measure. Materials and Methods: A cross-sectional study was conducted involving 74 patients diagnosed with OA. All patients were asked to complete the KOOS questionnaire. To test interrater reliability, two raters completed the questionnaire, while for test-retest reliability, one rater was involved. The procedure was repeated after a week. The scores of both questionnaires were then compared to check the inter-rater and test-retest reliability of the cross-culturally adapted KOOS outcome measure. Cronbach’s Alpha and the Intraclass Correlation Coefficient (ICC) were utilised to determine the scale’s reliability. Results: The entire scale demonstrated high reliability, with an ICC ranging from 0.96 to 0.98 for all subscales. The domainwise and overall Cronbach’s Alpha values were >0.70. There was agreement between the raters (p<0.01) and test-retest data (p<0.01) for pain and activities of daily living items. Highly significant correlations were also observed between test-retest data for all items related to sport and recreation function and knee-related quality of life (p<0.001). Conclusion: The Cronbach’s Alpha values obtained for all domains of the scale were >0.70, indicating the scale’s reliability. Additionally, the scale demonstrated consistency as the ICC was determined to be substantial.