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False-positive mammograms increase follow-up rates

J Fam Pract. 2003 July;52(7):512-525
By
Jennifer J. Buescher, MD
David S. White, MD
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  • BACKGROUND: Women enrolled in health maintenance organizations that use patient reminder systems have been shown to be more likely to receive subsequent mammography screening after a false-positive result. This study sought to determine screening follow-up rates in a population that did not receive reminders. It included women with and without health insurance.
  • POPULATION STUDIED: Women aged >40 years who had received mammograms in Vermont were identified during a 12-month period (in 1996 and 1997) through the Vermont Mammography Registry database. The index (initial) mammogram was defined as imaging that occurred during the enrollment period and was not necessarily the woman’s first screening.
  • STUDY DESIGN AND VALIDITY: A positive screening test was defined as a mammogram resulting in any recommendation other than routine screening, and a false-positive screen was defined as a positive mammogram that did not result in a cancer diagnosis within 1 year. Procedure dates, radiology reports, pathology reports, family history, medical history, and demographic characteristics are included within the statewide registry. The registry includes women regardless of insurance status, place of residence, or employment status.
  • OUTCOMES MEASURED: The primary outcome measured was the likelihood of having received follow-up screening mammography 18 and 30 months after the index mammogram or diagnostic follow-up exam. Screening rates were further analyzed for differences according to various demographic variables, including age, insurance status, breast cancer risk factors, race, and education.
  • RESULTS: Of the 37,862 records with available mammography data, 3982 (10.5%) had a false-positive result. This false-positive rate was higher than previously reported rates of 4.4%–7.8%.
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PRACTICE RECOMMENDATIONS

This population-based study found that women who had a false-positive mammogram had higher rates of rescreening at 18- and 30-month follow-up. In 10 years of annual screening, 50% of women will have a false-positive mammogram. However, the consequences of false-positives do not deter women from continued breast cancer screening.

When evaluating screening tests it is important to consider the effect of a false-positive test on the people being screened. The subsequent work-up for each false-positive may increase patient anxiety, total costs, and the risk of morbidity from unnecessary interventions.

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