Development and Validation of an Abbreviated Version of the Expanded Prostate Cancer Index Composite Instrument for Measuring Health-related Quality of Life Among Prostate Cancer Survivors

Abstract

Objectives-Widespread implementation of HRQOL measurement in prostate cancer practice and research requires concise instruments. Having 50 questions, the full-length Expanded Prostate cancer Index Composite (EPIC) is cumbersome to administer outside of studies focusing exclusively on HRQOL. To facilitate HRQOL measurement in a broad range of prostate cancer research and practice settings, we developed and validated an abbreviated version of EPIC.Methods-50 questions that comprise the full-length EPIC-50 were evaluated to identify items suitable for elimination while retaining ability to measure the 5 prostate cancer-specific HRQOL domains of EPIC-50. The resulting abbreviated version (EPIC-26) was validated using question responses from 252 subjects who had brachytherapy, external radiotherapy or prostatectomy for prostate cancer. EPIC-26 internal consistency was measured by Cronbach's alpha coefficient and reliability by test-retest correlation.Results-Based on high item-scale correlations, clinically relevant content, and preservation of domain psychometrics, 26 items were retained in EPIC-26 from 50 questions in the full length EPIC-50. High correlation was observed between EPIC-50 and EPIC-26 versions of urinary incontinence, urinary irritation/obstruction, bowel, sexual and vitality/hormonal domain scores (all r ≥0.96). Correlations between different domains were low, confirming that EPIC-26 retains the ability to discern 5 distinct HRQOL domains. Internal consistency and test-retest reliability for EPIC-26 (Cronbach's alpha ≥0.70 and r ≥ 0.69, respectively for all 5 HRQOL domains) support its validity.Conclusions-EPIC-26 is a brief, valid and reliable subjective measure of health quality among prostate cancer patients and suitable for measuring HRQOL among patients undergoing treatment for early stage prostate cancer.

Validation of the French-Canadian version of the Expanded Prostate Cancer Index Composite (EPIC) in a French-Canadian population

“…Overall, the psychometric properties found in this study are similar to those of the original English version. 6,8 Hence, results suggest that this French version is a reliable and valid instrument for assessing prostate cancer-related symptoms. Test-retest correlations at an interval of 2 to 4 weeks were high across all domains, suggesting an excellent reliability.…”

“…The 5-factor structure of the original EPIC-26 was in large part confirmed, 8 with the same two items being weakly correlated with their postulated factor (hematuria and breast problems). The 4-factor structure of the EPIC-50 was less sound with poor fit indices and seven items that loaded less strongly with their respective factor.…”

“…The EPIC-26 is highly correlated with the full questionnaire (rs>.96 for all domains). 8 This abbreviated version comprises five domains rather than four: urinary incontinence, urinary irritation/obstruction, bowel, sexual, and vitality/hormonal. The EPIC-26 has shown high internal consistency (Cronbach's alpha=.70-.90) and test-retest reliability at 2-4 week intervals (rs=.69-.90 for all 5 domains).…”

Patient-reported outcomes in cancer survivorship

“…It was derived from the UCLA-Prostate Cancer Index, and the initial EPIC instrument included a total of 50 questions assessing four domains: urinary, bowel, sexual, and hormonal [20]. Subsequently, shorter versions -EPIC-26 [21] and EPIC-CP (clinical practice) [22] -were developed which measure the same domains.…”

Patient‐reported outcome measures in metastatic prostate cancer

“…EPIC-26 is a useful tool to monitor domain-specific changes in HR-QOL among prostate cancer survivors over time, and can quantify changes resulting from the introduction of new treatments. 7 A working group for the International Consortium for Health and Outcome Measurements (ICHOM) has recently recommended EPIC-26 as a valuable tool for the standardised collection of data across different centres to allow internationally comparable collection of PROMs after treatment for localised prostate cancer. 8 The Expanded Prostate Cancer Index Composite for Clinical Practice (EPIC-CP) was developed for routine clinical care of patients with prostate cancer.…”