For patients with prostate cancer, validated and reliable instruments are essential for measuring patient-reported outcomes. The aim of this study was to validate the German version of the widely established Expanded Prostate Cancer Index Composite with 26 items (EPIC-26).
A German translation of the original questionnaire was tested in 3094 patients with localized or locally advanced (any T, any N and M0) prostate cancer with treatment intent (including radical prostatectomy, brachytherapy, active surveillance, watchful waiting). They completed the EPIC-26 questionnaire before treatment. A total of 521 of them also completed a questionnaire 12 months afterward. Internal consistency, sensitivity to change, and construct validity were assessed.
The internal consistency of all domains was sufficient (Cronbach’s alpha between 0.64 and 0.93). Item-to-scale correlation coefficients showed acceptable associations between items and their domain score (all > 0.30), with the lowest scores for “bloody stools” (r = 0.37) and “breast problems” (r = 0.32). Confirmatory and exploratory factor analysis confirmed the five-dimension structure of the EPIC-26 (comparative fit index 0.95).
Psychometric evaluation suggests that the German version of the EPIC-26 is a well-constructed instrument for measuring patient-reported health-related symptoms in patients with prostate cancer.
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This study was funded by the Movember Foundation.
Conflicts of interest
GC, GF, TS, JM, FR, FZ, AHi, BB, AHe, NH, BB, JP, JF, AN, and PH hereby declare that they have no potential conflicts of interest. NTS, CK, SD, AO, and SW are employees of the two institutions in charge of the certification system. BK receives consulting and lecturing honoraria from various companies that do not involve any conflicts with the research presented here. A comprehensive list is available on request.
Research involving human participants and/or animals
All procedures performed in studies involving human participants were in accordance with the ethical standards of the ethics committee of the Medical Association of Berlin (Eth-12/16) and with the 1964 Helsinki Declaration and its later amendments or comparable ethical standards.
Informed consent was obtained from all individual participants included in the study.
Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
Appendix 1: Comparison of the four-, five- and six-factor solutions
Appendix 2: The EPIC-26—Expanded Prostate Cancer Index Composite Short Form 
Appendix 3: German translation of the EPIC-26 
Appendix 4: Staging according to the German Guideline Prostate Cancer (version April 2018)
In this study we use the staging proposed by the German Guideline for Prostate Cancer :
Localized prostate cancer: T1-2, N0 M0.
Localized prostate cancer with low risk: PSA ≤ 10 ng/ml and Gleason-Score 6 and cT1c or cT2a.
Localized prostate cancer with intermediate risk: PSA > 10 ng/ml–30 ng/ml or Gleason 7 or cT 2b.
Localized prostate cancer with high risk: PSA > 20 ng/ml or Gleason ≥ 8 or cT2c.
Locally advanced prostate cancer: T3-4 N0 M0.
Advanced prostate cancer: any T N1 and M0.
Metastasized prostate cancer: any T any N and M1.
Furthermore, localized prostate cancer with cT1a or cT1b is classified as localized prostate cancer with low risk.
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Sibert, N.T., Dieng, S., Oesterle, A. et al. Psychometric validation of the German version of the EPIC-26 questionnaire for patients with localized and locally advanced prostate cancer. World J Urol 39, 11–25 (2021). https://doi.org/10.1007/s00345-019-02949-7
- Prostate cancer
- Patient-reported outcomes
- Health-related Quality of Life