Validity and reliability of Thai version of the International Knee Documentation Committee Subjective Knee Form

Abstract

Background: Self-administered questionnaires have become an important aspect for clinical outcome assessment of knee-related surgery. The International Knee Documentation Committee (IKDC) Subjective Knee Form is a knee-specific questionnaire that is widely used and translated to many languages. The purposes of the present study were: (1) to translate the questionnaire into Thai; and (2) to assess the validity and reliability of the Thai version of the International Knee Documentation Committee (IKDC) Subjective Knee Form. Material and Method: The IKDC Subjective Knee Form was translated into Thai using forward-backward translation protocol. Afterward, reliability and validity were tested. The responses of 55 consecutive patients on two questionnaires, the Thai IKDC Subjective Knee Form and the Short Form-36, were used. The validity was tested by correlating the scores from both questionnaires. The reliability was adopted by measuring the test-retest reliability and internal consistency. Results: The Thai IKDC Subjective Knee Form showed good correlations with the physical functioning and bodily pain domains of the SF-36 (Pearson's correlation coefficient = 0.75 and 0.76 respectively). The reliability proved excellent with an intra-class correlation coefficient of 0.92 for test-retest. The internal consistency was strong (Cronbach alpha = 0.92). Conclusion: The Thai version of IKDC Subjective Knee Form showed good value to retain the characteristic of the original version. In addition, it was a reliable evaluation instrument for patients with knee-related problems.