Validity of Korean versions of the multiple sclerosis impact scale and the multiple sclerosis international quality of life questionnaire

Background and Purpose Assessment of the health-related quality of life (HRQoL) is important in clinical evaluations of multiple sclerosis (MS) patients for quantifying the impact of illness and treatment on their daily lives. Although MS-specific HRQoL instruments have been used internationally, there are no data regarding HRQoL instruments specifically designed for patients with MS in Korea. The objective of this study was to determine the reliability and validity of the Korean Multiple Sclerosis Impact Scale (MSIS-29) and the Multiple Sclerosis International Quality of Life (MusiQoL) questionnaire. Methods Fifty-six patients with MS were recruited from June 2009 to February 2010 at the National Cancer Center in Korea. The original English versions of the MSIS-29 scale and the MusiQoL questionnaire were translated into Korean and evaluated for their acceptability, reliability, and validity. Results The patients wereaged 36.5±8.6 years (mean±SD; range, 20-56 years). Their score on the Expanded Disability Status Scale was 2.0±1.9 (mean; range, 0-7.5), and their disease duration was 5.2±4.7 years (mean±SD; range, 1-24 years). The Korean versions of the MSIS-29 and MusiQoL questionnaires showed satisfactory psychometric properties, including construct validity (item-internal consistencies of 0.59-0.95 and 0.59-0.92, respectively; item-discriminant validities of 95-100% and 93.8-100%), internal consistency (Cronbach's alpha coefficients of 0.96-0.97 and 0.77-0.96), reliability (intraclass correlation coefficients of 0.78-0.90 and 0.50-0.93), unidimensionality (Loevinger scalability coefficients of 0.70-0.78 and 0.63-0.90), and acceptability. External validity testing indicated the presence of significant correlations between similar aspects of the two questionnaires. Conclusions The Korean translated versions of the MSIS-29 and MusiQoL questionnaires demonstrated reliability and validity for measuring HRQoL in Korean patients with MS.