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The German version of the Expanded Prostate Cancer Index Composite (EPIC): translation, validation and minimal important difference estimation


Umbehr, Martin H; Bachmann, Lucas M; Poyet, Cedric; Hammerer, Peter; Steurer, Johann; Puhan, Milo A; Frei, Anja (2018). The German version of the Expanded Prostate Cancer Index Composite (EPIC): translation, validation and minimal important difference estimation. Health and Quality of Life Outcomes, 16:36.

Abstract

BACKGROUND No official German translation exists for the 50-item Expanded Prostate Cancer Index Composite (EPIC), and no minimal important difference (MID) has been established yet. The aim of the study was to translate and validate a German version of the EPIC with cultural adaptation to the different German speaking countries and to establish the MID. METHODS We translated and culturally adapted the EPIC into German. For validation, we included a consecutive subsample of 92 patients with localized prostate cancer undergoing radical prostatectomy who participated the Prostate Cancer Outcomes Cohort. Baseline and follow-up assessments took place before and six weeks after prostatectomy in 2010 and 2011. We assessed the EPIC, EORTC QLQ-PR25, Feeling Thermometer, SF-36 and a global rating of health state change variable. We calculated the internal consistency, test-retest reliability, construct validity, responsiveness and MID. RESULTS For most EPIC domains and subscales, our a priori defined criteria for reliability were fulfilled (construct reliability: Cronbach's alpha 0.7-0.9; test-retest reliability: intraclass-correlation coefficient ≥ 0.7). Cross-sectional and longitudinal correlations between EPIC and EORTC QLQ-PR25 domains ranged from 0.14-0.79, and 0.06-0.5 and 0.08-0.72 for Feeling Thermometer and SF-36, respectively. We established MID values of 10, 4, 12, and 6 for the urinary, bowel, sexual and hormonal domain. CONCLUSION The German version of the EPIC is reliable, responsive and valid to measure HRQL in prostate cancer patients and is now available in German language. With the suggested MID we provide interpretation to what extent changes in HRQL are clinically relevant for patients. Hence, study results are of interest beyond German speaking countries.

Abstract

BACKGROUND No official German translation exists for the 50-item Expanded Prostate Cancer Index Composite (EPIC), and no minimal important difference (MID) has been established yet. The aim of the study was to translate and validate a German version of the EPIC with cultural adaptation to the different German speaking countries and to establish the MID. METHODS We translated and culturally adapted the EPIC into German. For validation, we included a consecutive subsample of 92 patients with localized prostate cancer undergoing radical prostatectomy who participated the Prostate Cancer Outcomes Cohort. Baseline and follow-up assessments took place before and six weeks after prostatectomy in 2010 and 2011. We assessed the EPIC, EORTC QLQ-PR25, Feeling Thermometer, SF-36 and a global rating of health state change variable. We calculated the internal consistency, test-retest reliability, construct validity, responsiveness and MID. RESULTS For most EPIC domains and subscales, our a priori defined criteria for reliability were fulfilled (construct reliability: Cronbach's alpha 0.7-0.9; test-retest reliability: intraclass-correlation coefficient ≥ 0.7). Cross-sectional and longitudinal correlations between EPIC and EORTC QLQ-PR25 domains ranged from 0.14-0.79, and 0.06-0.5 and 0.08-0.72 for Feeling Thermometer and SF-36, respectively. We established MID values of 10, 4, 12, and 6 for the urinary, bowel, sexual and hormonal domain. CONCLUSION The German version of the EPIC is reliable, responsive and valid to measure HRQL in prostate cancer patients and is now available in German language. With the suggested MID we provide interpretation to what extent changes in HRQL are clinically relevant for patients. Hence, study results are of interest beyond German speaking countries.

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Item Type:Journal Article, refereed, original work
Communities & Collections:04 Faculty of Medicine > University Hospital Zurich > Clinic and Policlinic for Internal Medicine
04 Faculty of Medicine > Epidemiology, Biostatistics and Prevention Institute (EBPI)
Dewey Decimal Classification:610 Medicine & health
Uncontrolled Keywords:EPIC, Prostate Cancer, Quality of Life Assessment
Language:English
Date:20 February 2018
Deposited On:01 Nov 2018 09:59
Last Modified:24 Sep 2019 23:50
Publisher:BioMed Central
ISSN:1477-7525
OA Status:Gold
Free access at:PubMed ID. An embargo period may apply.
Publisher DOI:https://doi.org/10.1186/s12955-018-0859-1
PubMed ID:29458434

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