Validation study of the Korean version of the neurocognitive questionnaire in the childhood cancer survivor study

Neurocognitive sequelae are common late complications in childhood cancer survivors (CCS), impacting quality of life, yet no validated Korean tool exists to screen neurocognitive function effectively. Korean CCS (N = 638) and their siblings (N = 218) were included from a cohort study of Korean CCS at three major hospitals in South Korea. To determine the underlying structure of K-NCQ, exploratory factor analysis and confirmatory factor analysis were performed. Pearson's correlations were used to evaluate concurrent and convergent validity. We also explored known-group validity of K-NCQ by comparing the score of K-NCQ across the four risk stratified groups. The mean age of the study participants was 17.5 +/- 4.7 years at the time of the survey and 8.8 +/- 5.2 years at the time of cancer diagnosis. Exploratory factor analysis supported the five-factor structure within the original four-domains (factor 2 and factor 5 can be incorporated under emotional regulation domain), and confirmatory factor analysis supported the five-factor structure, excluding one item with cross-loadings (item 8) within the original four domains, demonstrating a sufficient level of goodness-of-fit indices (comparative fit index = 0.926, root mean square error of approximation = 0.045). The K-NCQ demonstrated high internal consistency (alpha = 0.91 for the total scale and alpha = 0.74-0.89 for each subdomain). Moderate correlations were found between K-NCQ domains and subscales of other questionnaires and tests for cognitive function. Our study demonstrated the validity of K-NCQ, thus supporting that K-NCQ is a useful tool to assess the neurocognitive function in Korean CCS in clinical settings.