Effect of false-positive screening mammograms on rescreening in Western Australia

Objectives: To quantify the effect of previous false-positive mammogram results on rescreening rates in a population of women participating in the BreastScreen WA (BSWA) program. Design and participants: Retrospective cohort study of women aged 50-69 years who received free screening mammograms at BSWA between 1 January 1995 and 31 December 2007. Main outcome measures: Percentages of women attending rescreening, and risk ratios for rescreening. Results: A total of 22 396 screening mammograms were falsely reported as positive, and 560 333 mammogram screens were reported as normal (negative). Women with a false-positive index mammogram result were less likely than women with a true-negative index mammogram result to attend rescreening at 27 months (67.6% v 70.7%; risk ratio, 0.96; P < 0.001). A reduced rescreening rate was seen in all subgroups of women except Indigenous women. Rescreening rates were affected by the types of assessment done at the recall visit. Conclusion: Mammographic population screening services should keep their false-positive result rates low, to prevent women from being deterred from screening.