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.