Assuming an overall 30% reduction in breast cancer mortality, the incremental cost-effectiveness ratio of annual screening mammography versus observation was $15,500, $35,000 and $26,200 for the age groups 60-69, 80-85 and 40-49 respectively. Since estimates of the reduction in mortality due to screening in the 40-49 year-old group is controversial, the effect of various hypothetical reductions in mortality rates on the incremental cost-effectiveness ratios were calculated for this age group. As a result, the ratios ranged from $138,000 with a 10% reduction in mortality to $18,500, with a 40% reduction in mortality. However, if costs and benefits were discounted the incremental cost per life year gained for the 40-49 year-old age group rose from $26,200 to $46,300.
For age group 40-49, the incremental cost per life year saved was $26,200 and $14,000 for annual and biennial screening respectively,assuming a 30% reduction in mortality. Alternatively, the authors calculated $44,000 and $23,000 per life year saved, assuming a 20% reduction in mortality for annual and biennial screening.