Elsevier

Urology

Volume 56, Issue 6, December 2000, Pages 899-905
Urology

Rapid communication: CME article
Development and validation of the expanded prostate cancer index composite (EPIC) for comprehensive assessment of health-related quality of life in men with prostate cancer

https://doi.org/10.1016/S0090-4295(00)00858-XGet rights and content

Abstract

Objectives. Health-related quality of life (HRQOL) is an increasingly important endpoint in prostate cancer care. However, pivotal issues that are not fully assessed in existing HRQOL instruments include irritative urinary symptoms, hormonal symptoms, and multi-item scores quantifying bother between urinary, sexual, bowel, and hormonal domains. We sought to develop a novel instrument to facilitate more comprehensive assessment of prostate cancer-related HRQOL.

Methods. Instrument development was based on advice from an expert panel and prostate cancer patients, which led to expanding the 20-item University of California-Los Angeles Prostate Cancer Index (UCLA-PCI) to the 50-item Expanded Prostate Index Composite (EPIC). Summary and subscale scores were derived by content and factor analyses. Reliability and validity were assessed by test-retest correlation, Cronbach’s alpha coefficient, interscale correlation, and EPIC correlation with other validated instruments.

Results. Test-retest reliability and internal consistency were high for EPIC urinary, bowel, sexual, and hormonal domain summary scores (each r ≥0.80 and Cronbach’s alpha ≥0.82) and for most domain-specific subscales. Correlations between function and bother subscales within domains were high (r >0.60). Correlations between different primary domains were consistently lower, indicating that these domains assess distinct HRQOL components. EPIC domains had weak to modest correlations with the Medical Outcomes Study 12-item Short-Form Health Survey (SF-12), indicating rationale for their concurrent use. Moderate agreement was observed between EPIC domains relevant to the Functional Assessment of Cancer Therapy Prostate module (FACT-P) and the American Urological Association Symptom Index (AUA-SI), providing criterion validity without excessive overlap.

Conclusions. EPIC is a robust prostate cancer HRQOL instrument that complements prior instruments by measuring a broad spectrum of urinary, bowel, sexual, and hormonal symptoms, thereby providing a unique tool for comprehensive assessment of HRQOL issues important in contemporary prostate cancer management.

Section snippets

Instrument development

Content from the original University of California-Los Angeles Prostate Cancer Index (UCLA-PCI)5 was expanded with guidance from a development cohort of localized prostate cancer patients and an expert panel comprised of urologic oncologists, radiation oncologists (including brachytherapy expertise), survey researchers, and prostate cancer nurses. Patient experts were unselected volunteers from our multidisciplinary urologic oncology clinics who had undergone the range of therapies represented

Results

Relevant EPIC validation cohort characteristics appear in Table I. Unique features of this cohort include equal representation of subjects between brachytherapy, external beam radiation, and radical prostatectomy, as well as representation of patients who received hormonal therapy. These characteristics were sought to ensure adequate representation of side effects from each therapy. To determine valid EPIC item groupings for HRQOL domain scores, survey item responses were evaluated by factor

Comment

Existing HRQOL instruments that have been validated for use in prostate cancer studies are limited in evaluating contemporary prostate cancer therapies.5, 6, 7, 10, 11, 12, 13, 14, 15 These limitations include lack of irritative and obstructive urinary symptom assessment (complementing concurrent incontinence assessment), lack of multi-item scales for measuring function-related bother, and lack of validated, multi-item summary scores to specifically measure hormonal therapy effects and their

Acknowledgements

This article benefited from the guidance of an expert panel comprised of radiation oncologists (P. William McLaughlin, M.D. and John Fiveash, M.D., in addition to coauthor H.M.S.); prostate cancer nurses (Peg Esper, M.S.N., Phil Rupp, M.S.N., and Chris Brown, R.N.); urologists (James E. Montie, M.D., in addition to coauthors J.T.W. and M.G.S.); and a medical oncologist (Ken Pienta, M.D.) for recommendations regarding items to improve instrument content. We thank Michael Miklosovic, M.S. for

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Supported by National Institutes of Health grants 5P30CA46598 and 1P50CA69568 (National Cancer Institute Prostate Cancer Specialized Projects of Oncology Research Excellence [SPORE]), American Cancer Society Clinical Career Development Award 96-77 (M.G.S.), Robert Wood Johnson Scholars Program (J.T.W.), and American Foundation for Urological Diseases Fellowship Award (J.T.W.).

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