Accuracy of Colorectal Polyp Self-Reports: Findings from the Colon Cancer Family Registry

^{1 1}UCSD Moores Cancer Center, University of California, San Diego, California; ²Cancer Care Ontario; ³Samuel Lunenfeld Research Institute, University of Toronto, Toronto, Ontario, Canada; ⁴Epidemiology Program, Cancer Research Center of Hawaii, University of Hawaii, Manoa, Hawaii; ⁵Department of Preventive Medicine, University of Southern California-Keck School of Medicine, Los Angeles, California; ⁶Centre for Molecular, Environmental, Genetic and Analytic Epidemiology, The University of Melbourne, Melbourne, Victoria, Australia; ⁷Mayo Clinic, Rochester, Minnesota; ⁸South Australian Familial Cancer Unit, Womens and Childrens Hospital, North Adelaide, Australia; ⁹Cancer Prevention Program, Fred Hutchinson Cancer Research Center, Seattle, Washington; and ¹⁰Departments of Medicine and Community and Family Medicine, Dartmouth Medical School, Hanover, New Hampshire

^* To whom correspondence should be addressed. E-mail: lmadlensky{at}ucsd.edu.

	Abstract

Introduction: Colorectal adenomas and other types of polyps are commonly used as end points or risk factors in epidemiologic studies. However, it is not known how accurately patients are able to self-report the presence or absence of adenomas following colonoscopy.

Methods: Participants in the Colon Cancer Family Registry provided self-reports of recent colorectal cancer (CRC) screening activity, and whether or not they had ever been told they had a polyp. Positive and negative predictive values for polyp self-report were calculated by comparing medical records with self-reports from 488 participants.

Results: The positive predictive value for self-reported polyp was 80.9%, and the negative predictive value was 85.8%. The predictive values did not differ by age group or sex, but participants with a previous diagnosis of CRC had a lower negative predictive value (76.2%) than participants with no personal history of CRC (89.0%; P = 0.04).

Conclusions: Predictive values for self-reports of polyps are fairly high, but researchers needing accurate polyp data should obtain medical record confirmation. Pursuing medical records on only those participants self-reporting a polyp could result in an underestimation of the polyp prevalence in a study population. (Cancer Epidemiol Biomarkers Prev 2007;16(9):OF1–4)

Key Words: Self-report, polyp, validation, medical records, Gastrointestinal cancers: colorectal, Premalignant lesions, Methodologic Studies, Cancer surveillance and screening, Descriptive, Risk Factor, and Methodologic Studies