False-positive mammographic screening: factors influencing re-attendance over a decade of screening.

Introduction: International studies on the effect of false-positive mammographic screening results on subsequent re-attendance at screening are inconsistent.

Setting: BreastCheck, the national breast screening programme for the Republic of Ireland, screens women two-yearly. Re-attendance for subsequent screening is approximately 90%.

Objectives And Methods: The aim of this research was to quantify the impact of false-positive mammographic screening results on subsequent re-attendance, using the BreastCheck clinical database with a decade of screening and to determine if age group, assessment procedure, initial or subsequent screening, location of appointment for next screening round and time from recall to non-malignant diagnosis predicted re-attendance.

Results: From programme commencement in 2000 to the end of 2007, 13,352 screening tests resulted in assessment; 11,765 participants were aged 50-62 years and of these 9746 received false-positive results (positive predictive value 17.2%). Following a false-positive recall to assessment, re-attendance at subsequent screening differed significantly by procedure type (open biopsy 80.3%; core biopsy only 90.2%; no tissue sampling 91.4%; P < 0.0001). Re-attendance differed significantly by timing of false-positive assessment in a woman's screening history (first versus subsequent screening, 89.5% versus 93.5%, P < 0.0001) and by location of next screening appointment (screening centre 89.8% versus mobile unit 91.3%, P < 0.01). The longer the period between recall to assessment and non-malignant diagnosis the less likely women were to re-attend. After logistic regression, first screening, older age, open surgical biopsy, re-invitation to screening centre and a longer period between recall and non-malignant diagnosis were significant negative predictors of re-attendance.

Conclusion: Since April 2008 BreastCheck has employed full field digital mammography throughout the programme, with a resulting increase in recalls; re-attendance will be closely monitored.