A cross-cultural translation and validation of the Korean version of checklist individual strength (CIS) in the Korean working age population

Checklist Individual Strength (CIS) is a widely used questionnaire to measure a level of the chronic fatigue syndrome. The purpose of this study was to translate CIS into Korean and evaluate the reliability and validity of a Korean version of CIS (K–CIS) for the Korean working age population. In the first experimentation of the study, four bilingual translators participated to translate CIS using a cross-cultural translation method. Then, a concurrent validity of K–CIS with the original CIS was evaluated by 28 bilingual participants. With a statistical analysis, it was confirmed that K–CIS and CIS were linguistically equivalent. In the second experimentation, 172 participants from various universities, industries, and small businesses assessed K–CIS along with two other representative fatigue questionnaires such as mKCFQ11 and SF-36. Our result of the statistical analysis using Cronbach's α, confirmatory factor analysis, inter-scale correlation, and correlation with other questionnaires showed that K–CIS was a valid fatigue questionnaire. Therefore, we conclude that K–CIS can be an effective tool to evaluate a severity of fatigue in the Korean working age population.