Reliability and validity verification of the expanded prostate cancer index composite 26-item version in Chinese

Abstract

Objective To analyze the reliability and validity of the Expanded Prostate cancer Index Composite 26-item version (EPIC-26) in Chinese patients with prostate cancer. Methods Totally 402 patients with prostate cancer at the Fudan University Shanghai Cancer Center were invited to fill in the Chinese version of EPIC-26. 402 samples were divided into two parts by random number table method. 201 samples were analyzed by exploratory factor analysis and another 201 samples were analyzed by confirmatory factor analysis. Results The total Cronbach alpha coefficient of Chinese version EPIC-26 was 0.845, and the Cronbach′s α coefficient of each domain ranged from 0.576 to 0.957. The results of exploratory factor analysis showed that the Chinese version of EPIC-26 was a 5-factor model, which could explain 63.456% of the total variance. The results of confirmatory factor analysis were as follows: χ2/df=1.641, GFI=0.863, AGFI=0.829, NFI=0.886, IFI=0.952, CFI=0.951, TLI=0.944, RMSEA= 0.057, which all met the standard of model fitting. Conclusion The Chinese version of EPIC-26 is a reliable and valid tool which is suitable for assessing the health-related quality of life of Chinese patients with prostate cancer. Key words: Expanded Prostate cancer Index Composite 26-item version; Exploratory factor analysis; Confirmatory factor analysis