Introduction: This study aims to empirically validate the French-Canadian version of the Expanded Prostate Cancer Index Composite (EPIC), a measure of health-related quality of life for prostate cancer patients.
Methods: Two hundred fifty-one participants completed a battery of self-report scales, including the French-Canadian version of the EPIC, after having received radiation therapy or radical prostatectomy for prostate cancer.
Results: The internal consistency for the urinary incontinence, bowel, and sexual domains of the EPIC-26 was high (Cronbach's alpha coefficients from 0.80-0.92), while coefficients for the urinary irritation/obstruction (0.59) and hormonal (0.67) domains were lower. Item-total correlations (rs=0.15-0.85), and temporal stability (rs=0.72-0.93) generally supported the reliability of the instrument. The five-factor structure of the EPIC-26 was confirmed for the most part. The construct validity of the instrument was also supported by high correlations obtained between each domain and measures assessing similar constructs (rs=-0.56-0.83). The EPIC also showed an excellent sensitivity to change with significant differences obtained on EPIC scores (all p<0.05) between pre- and post-prostate cancer treatment.
Conclusions: The psychometric qualities of the French-Canadian version of the EPIC are well-supported, thus providing a valid tool to assess health-related quality of life in prostate cancer patients.