Validation of the Korean Leeds satisfaction questionnaire in rheumatoid arthritis with Rasch models

Objectives We conducted the cross-cultural adaptation and validation of the Leeds Satisfaction Questionnaire (LSQ) for patients with rheumatoid arthritis (RA) in Korea. Methods The adaptation of the LSQ from English into Korean was based on guidelines for cross-cultural adaptation for self-report measures. Patients with RA were recruited from an outpatient clinic of a university hospital in South Korea. Validation of the Korean-LSQ with Rasch models was carried out using WINSTEPS. Model fit was determined by Infit and Outfit statistics (>= 0.50 and <= 1.50), including the separation index (>= 2.00) and reliability index (>= 0.80). Results The data set comprised 125 patients (82.4% female), with median (interquartile range) age 49.0 (37-57) years, and disease duration of 2.5 (1.2-3.8) years. The total and subscale scores of the Korean-LSQ demonstrated excellent or good test-retest reliability (0.88 for total, 0.71-0.82 for subscales), and items in the scale also revealed a high internal consistency (alpha = 0.93). The six subscales of the Korean-LSQ were found to have a good fit to the Rasch model and good reliability (Person separation index = 2.63 and reliability index = 0.87; item separation index = 37.03 and reliability index >0.99). In addition, the unidimensionality of the scale was confirmed by the principal component analysis based on the Rasch residuals. Conclusion Fit to the Rasch model confirmed that the construct validity, reliability, and unidimensionality of the LSQ were preserved following the adaptation into Korean. The Korean-LSQ is a valid and reliable tool for measuring satisfaction with care in Korean patients with RA.