The psychometric properties of the Korean version of the functional assessment of cancer therapy-cognitive (FACT-Cog) in Korean patients with breast cancer

The aim of this study was to evaluate the psychometric properties of the Korean version of the Functional Assessment of Cancer Therapy-Cognitive scale (FACT-Cog) in patients with breast cancer in Korea. The FACT-Cog was translated into Korean using forward and back translation. Patients with breast cancer who had undergone chemotherapy were enrolled from the university hospital and assessed using the Korean version of the FACT-Cog, the cognitive functioning scale of the EORTC-QLQ-C30 (EORTC-CF), and the Beck Depression Inventory-Second Edition (BDI-II). Analyses of internal consistency, construct validity, concurrent validity, and convergent validity were performed to evaluate the psychometric characteristics. A total of 250 patients completed the questionnaire. There were no missing data and patients completed the scale within 10 min. The Korean version of the FACT-Cog had acceptable internal consistency, with Cronbach's alpha coefficients of 0.94 for the total scores and 0.87-0.95 for the four subscales. The item-total correlation coefficients ranged from 0.36 to 0.95. Moderate correlations were found (r = 0.33 to 0.53) between the Korean version of the FACT-Cog and the EORTC-CF. There was acceptable convergent validity, with weak and moderately significant correlations (r = -0.41 to -0.22) between the Korean version of the FACT-Cog and the BDI-II. Confirmatory factory analysis supported a four-factor structure of the Korean version of the FACT-Cog with a good model fit. The Korean version of the FACT-Cog is a valid and reliable scale to measure self-reporting of cognitive impairment in patients with breast cancer who are undergoing chemotherapy.