Objective: To illustrate visually the lifetime probabilities of the principal outcomes of the UK breast screening programme in a readily understandable format.
Methods: We derived prognostic data from a modelling exercise using published effectiveness data and routine data sources. We calculated the probability that a woman will survive to the age of 75 if she chooses to participate fully in breast screening from age 50 to 64 and if she chooses not to participate. We also calculated her probability of being referred for assessment, undergoing fine-needle biopsy and undergoing open biopsy. We present these data in two alternative decision aid formats. These alternative formats illustrate visually the outcomes for 1000 women and 100 women choosing each alternative: breast screening or no breast screening.
Results: A woman participating in breast screening from age 50 to 64 increases her chances of surviving to age 75 by 0.6%. She has a 21.8% probability of surviving to age 75 and being referred for assessment but no further investigation. She has a 5.7% probability of undergoing core biopsy and a 0.9% probability of undergoing open biopsy. This information can easily be presented visually.
Conclusions: We can provide realistic estimates of the effects of the breast screening programme on mortality in a readily understandable format. If we wish women to make an informed choice about breast screening they must be given this information.