title: Minimally important difference for the Expanded Prostate Cancer Index Composite Short Form.
abstract: 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).
  
  
  CONCLUSIONS
  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.
authors.affiliation: Department of Urology, Dow Division of Health Services Research, University of Michigan, Ann Arbor, MI; Division of Oncology, University of Michigan, Ann Arbor, MI; VA HSR&D Center for Clinical Management Research, VA Ann Arbor Healthcare System, Ann Arbor, MI. Electronic address: tskolar@med.umich.edu.
authors.forename: Ted A
authors.initials: TA
authors.lastname: Skolarus
authors.affiliation: Department of Urology, Dow Division of Health Services Research, University of Michigan, Ann Arbor, MI.
authors.forename: Rodney L
authors.initials: RL
authors.lastname: Dunn
authors.affiliation: Department of Urology, Emory University, Atlanta, GA.
authors.forename: Martin G
authors.initials: MG
authors.lastname: Sanda
authors.affiliation: Division of Urology, Department of Surgery, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA.
authors.forename: Peter
authors.initials: P
authors.lastname: Chang
authors.affiliation: Alcohol Research Group, Public Health Institute, Emeryville, CA.
authors.forename: Thomas K
authors.initials: TK
authors.lastname: Greenfield
authors.affiliation: Department of Urology, David Geffen School of Medicine at UCLA, UCLA Fielding School of Public Health, Los Angeles, CA.
authors.forename: Mark S
authors.initials: MS
authors.lastname: Litwin
authors.affiliation: Department of Urology, Dow Division of Health Services Research, University of Michigan, Ann Arbor, MI.
authors.forename: John T
authors.initials: JT
authors.lastname: Wei
mesh_terms: D006801:Humans; D008297:Male; D011446:Prospective Studies; D011471:Prostatic Neoplasms / Q000175:diagnosis; D011788:Quality of Life; D011996:Records; D011795:Surveys and Questionnaires