The effect of false positive breast screening examinations on subsequent attendance: retrospective cohort study.

Objectives: To investigate the effect of false positive breast screening examination results on subsequent attendance in the UK National Health Service Breast Screening Programme.

Methods: 253,017 previously screened women who were invited for rescreening were studied. Attendance rates of women who had received a normal result at the last (index) screen were compared with those of women who had received a false positive result. The effects of age, type of index screening examination (prevalent or incident) and tissue sampling at assessment were investigated.

Results: Women who had a false positive prevalent index screening examination were significantly more likely to reattend than those who had a normal prevalent index screening examination (87.7% vs. 86.0%). There was no significant difference in reattendance rates between women who had a false positive incident index screening examination and those with a normal incident index screening examination. However, women who underwent needle sampling or open biopsy following false positive incident index screening examinations were 12% and 60% less likely to reattend, respectively, than women whose index screening examinations were normal (p < 0.001), although there was variation between centres. Increasing age significantly reduced the likelihood of reattendance. The overall reattendance of women who had been screened only once was six percentage points lower than that of women who had been screened more than once.

Conclusions: The findings suggest that most women who undergo the breast screening assessment process retain confidence in breast screening. Needle sampling and open biopsy should be used judiciously in the assessment of screen-detected abnormalities in view of the reduced reattendance that results from their use after incident screening examinations.