Adaptation of the knee quality of life 26 item questionnaire to Turkish: Cultural adaptation, reliability and validity

The aim of this study is to translate The Knee Quality of Life 26 item Questionnaire (KQoL-26) into Turkish, and to investigate its (DYK-26) reliability and validity. One hundred and eighty-two volunteer patients over the age of 40 with primary knee osteoarthritis were included in the study. DYK-26 was translated and culturally adapted according to the guidelines of Guillemin and Beaton. Comprehensibility of DYK-26 was tested in a pilot study (n=20). Demographic and clinical characteristics of the patients were recorded. Patients were completed SF-36, KOOS and WOMAC surveys along with the Turkish version of DYK-26. 3 days after the initial evaluation, patients were asked to refill the DYK-26. Correlation between the total results of both tests was determined intraclass correlation coefficient (ICC). Internal consistency was tested using Cronbach's α coefficient. Validity was assessed by calculating the Pearson's correlation coefficient between the DYK-26 and SF-36, WOMAC, KOOS scores. The average age of the participants was 59.96±8.47 years and 72.5% (n=132) of them were women. The overall internal consistency coefficient of the scale was calculated as α =0.965. Cronbach's α for physical function, activity limitations, and emotional function subscales were calculated as 0.945, 0.915, and 0.903, respectively. It was determined that the internal consistency was at high level. It was seen that ICC values were between 0.791-0.954 on the basis of questions, and ICC values of subscales were between 0.948-0.963. It was determined that the scores of this measure were positively correlated with the scores of KOOS and SF-36, and negatively correlated with the scores of WOMAC (p<0.01). The highest correlation was between physical function subscales of the SF-36 and DYK-26 scales (r=0.901). KQoL-26 is a reliable and valid Turkish measure to assess knee-related quality of life in patients with knee osteoarthritis.