Psychometric validation study of the Korean version of the Functional Assessment of Cancer Therapy-Vanderbilt Cystectomy Index.

Abstract

PURPOSES: To evaluate the reliability and validity of a Korean version of the Functional Assessment of Cancer Therapy (FACT)-Vanderbilt Cystectomy Index (VCI) in Korean patients who underwent radical cystectomy (RC) and urinary diversion (UD). MATERIALS AND METHODS: We prospectively recruited 108 RC and UD patients who did not have evidence of recurrence from 1994 December to 2015 March. All participants were instructed to complete the Korean FACT-VCI and Short-Form 36-Item Health Survey (SF-36; 1st measurement) and to repeat the Korean FACT-VCI survey one month later (2nd measurement). Statistical analysis included intraclass correlation, Cronbach's α, time and UD type fixed mixed linear model, principal components analysis, and criterion-related validity with SF-36. RESULTS: Korean FACT-VCI was internally consistent (α = 0.802) and had adequate test-retest reliability (interclass correlation = 0.803 and 0.822). The three components model of principal component analysis (cumulative explanatory power, 49.2%) confirmed the internal structural validity of the additional concerns (AC) component of the Korean FACT-VCI, and each component represented the "voiding problem", "bowel problem", and "social/functional problem with equivalent explanatory power (19.5%, 15.4%, and 14.4%). Korean FACT-VCI domain scores were generally well correlated with SF-36 domain scores (Pearson correlation coefficients range: 0.286-0.688; all p <0.01). Mixed linear models revealed that the major effect of measurement times was not significant on FACT-VCI (p = 0.589). CONCLUSIONS: This prospective study confirms the reliability and validation of the Korean FACT-VCI. We expect that this validated tool can be widely utilized in the health-related quality of life studies of Korean patients.