The Reliability and Validity of the Korean Versions of the International Restless Legs Scale and the Restless Legs Syndrome Quality of Life Questionnaire

ABSTRACT

BACKGROUND: The International Restless Legs Scale (IRLS) and the Restless Legs Syndrome Quality of Life questionnaire (RLSQoL) are valid and reliable tools for assessing RLS severity and the impact of RLS on daily life in Western countries. The purpose of this study was to validate the Korean versions of these questionnaires in Korean RLS patients. METHODS: We developed the Korean versions of the IRLS and the RLSQoL. In total, 250 Korean primary RLS patients were included in this study. These questionnaires were used for the initial interview and a subsequent retest approximately 1 month later. The findings were compared with those obtained using the Clinical Global Impression, Short Form 36 Health Survey, and other instruments. The percentage agreement and Cronbach's alpha were calculated for each question, and the validity coefficients were estimated from these statistics. RESULTS: The scores for the Korean versions of the IRLS (range 0-40) and the RLSQoL (range 0-100) proved reliably consistent (Cronbach's alpha=0.96 and 0.92, respectively) and had good test-retest reliability (intraclass correlation coefficient=0.61-0.85 and 0.61-0.89, respectively). The Korean version of the RLSQoL could be used to distinguish between groups with none, mild, moderate, severe, and very severe symptoms (F=66.10, P<0.0001). The two questionnaires proved to have high reliability and validity coefficients. CONCLUSIONS: The Korean versions of the IRLS and the RLSQoL are valid and reliable tools for assessing RLS severity and the impact of RLS on the daily life of Korean RLS patients.