Elsevier

Urology

Volume 85, Issue 1, January 2015, Pages 101-106
Urology

Health Services Research
Minimally Important Difference for the Expanded Prostate Cancer Index Composite Short Form

https://doi.org/10.1016/j.urology.2014.08.044Get rights and content

Objective

To establish a score threshold that constitutes a clinically relevant change for each domain of the Expanded Prostate Cancer Index Composite (EPIC) Short Form (EPIC-26). Although its use in clinical practice and clinical trials has increased worldwide, the clinical interpretation of this 26-item disease-specific patient-reported quality of life questionnaire for men with localized prostate cancer would be facilitated by characterization of score thresholds for clinically relevant change (the minimally important differences [MIDs]).

Methods

We used distribution- and anchor-based approaches to establish the MID range for each EPIC-26 domain (urinary, sexual, bowel, and vitality/hormonal) based on a prospective multi-institutional cohort of 1201 men treated for prostate cancer between 2003 and 2006 and followed up for 3 years after treatment. For the anchor-based approach, we compared within-subject and between-subject score changes for each domain to an external “anchor” measure of overall cancer treatment satisfaction.

Results

We found the bowel and vitality/hormonal domains to have the lowest MID range (a 4-6 point change should be considered clinically relevant), whereas the sexual domain had the greatest MID values (10-12). Urinary incontinence appeared to have a greater MID range (6-9) than the urinary irritation/obstruction domain (5-7).

Conclusion

Using 2 independent approaches, we established the MIDs for each EPIC-26 domain. A definition of these MID values is essential for the researcher or clinician to understand when changes in symptom burden among prostate cancer survivors are clinically relevant.

Section snippets

Study Population

We identified a longitudinal cohort of 1201 men with stage T1 or T2 prostate cancer based on a previously reported multi-institutional study.1 The men in our study received primary treatment between March 2003 and March 2006 with radical prostatectomy, brachytherapy, or external beam radiotherapy at 1 of 9 university-affiliated hospitals. We examined their longitudinal EPIC-26 data before treatment and for 3 years after treatment. The institutional review boards at each site approved the parent

Results

The SD in EPIC-26 domain scores ranged from 8.8 to 27.7 pretreatment and from 12.6 to 31.9 at 3 years. Sexual domain scores tended to have the highest SD at each time point. The corresponding distribution-based one-third and half SD values, analogous to MID values, demonstrated similar variability over time as shown in Table 1. The differences between using a one-third or half SD approach to define MIDs ranged from roughly 2 to 5 EPIC-26 points, with the greatest differences in the sexual

Comment

We used distribution- and anchor-based approaches to establish MIDs (ie, clinically relevant) for each EPIC-26 domain. In general, MID estimates were consistent between methods for most domains. Clinically meaningful changes in EPIC-26 scores ranged from 4 to 12 points depending on the domain. We believe the EPIC-26 MID values provided in this study offer the necessary context for determining when changes in symptom burden among prostate cancer survivors are significant. In addition, these

Acknowledgments

The PROSTQA Consortium includes contributions in cohort design, patient accrual, and follow-up from the following investigators: Meredith Regan (Dana-Farber Cancer Institute, Boston, MA); Larry Hembroff (Michigan State University, East Lansing, MI); John T. Wei, Dan Hamstra, Rodney Dunn, Laurel Northouse, and David Wood (University of Michigan, Ann Arbor, MI); Eric A. Klein and Jay Ciezki (Cleveland Clinic, Cleveland, OH); Jeff Michalski and Gerald Andriole (Washington University, St. Louis,

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    • Cited by (0)

    A full list of authors “PROSTQA Consortium” is available in the Acknowledgments section.

    Financial Disclosure: Ted A. Skolarus is supported by a VA HSR&D Career Development Award 2 (CDA 12-171). Martin Sanda receives research grants from National Institutes of Health, Prostate Cancer Foundation, and Movember. Peter Chang is supported by a grant from the Urology Care Foundation Research Scholar Program and Dornier Medtech entitled “Measuring Prostate Cancer Patient Reported Outcomes at the Point of Care.” Thomas K. Greenfield is supported by a National Institute on Alcohol Abuse and Alcoholism Center grant (P50 AA005595). PROSTQA Consortium is supported by National Institutes of Health grants R01 CA95662 and RC1 CA146596. The remaining authors declare that they have no relevant financial interests.

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