Cross-cultural adaptation and psychometric validation of the Finnish version of the Expanded Prostate Cancer Index Composite-26 for patients with localised prostate cancer

Abstract

Objective: The study aimed to culturally adapt the Expanded Prostate Cancer Composite-26 (EPIC-26) questionnaire to Finnish and evaluate its usability in routine clinical practice in Finland. Material and methods: We translated the EPIC-26 questionnaire into Finnish, reviewed it, back-translated it into English, and reviewed it again. We evaluated the questionnaire in four high-volume university hospitals in Finland. The study included 220 Finnish-speaking patients with untreated, newly diagnosed non-metastatic prostate cancer. Patients completed the EPIC-26 twice before treatment and twice 6 months after treatment. We assessed internal consistency, test-retest reliability, sensitivity to change, and unanswered questions. Results: The mean age of the patients was 68 years, with 69% diagnosed with low-or intermediate-risk prostate cancer according to the D’Amico classification. The most common treatment was radical prostatectomy (36%), followed by radiation therapy (31%) and active surveillance (25%). The minimum score, i.e. the worst assessment, was observed most frequently in the sexual domain (8%), while the maximum score was in the bowel domain (47%). Irritation/obstruction and hormonal domains showed low internal consistency due to the questions regarding haematuria and breast problems. Patients who under-went radical prostatectomy or radiation therapy had statistically significant changes between pre-and post-treatment scores. Most men (72%) completed the questionnaire. Older patients were more prone to leave questions unanswered, particularly questions with multiple items (odds ratio 0.39; 95% confidence interval 0.20–0.80). Conclusions: The Finnish version of the EPIC-26 questionnaire can be used in clinical practice. Completing the questionnaire may be more difficult for older patients.