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# Table 2 Number of mammogram examinations needed to prevent one death.*

Age 10% RRR 15% RRR 20% RRR Range 20% 25% RRR 30% RRR
40 11050 7370 5530 2820–11630 4420 3680
45 7700 5130 3850 1980–8070 3080 2570
50 5950 3970 2970 1540–6160 2380 1980
55 5000 3330 2500 1320–5100 2000 1670
60 4460 2970 2230 1200–4450 1780 1490
65 4120 2750 2060 1130–4020 1650 1370
1. * Number of examinations is 5.25 times the number need to screen repeatedly (NNSR), which is the reciprocal of the reduction in absolute death risk (RADR) in Figure 1. The number needed to screen once (NNSO) is equivalent to the number of examinations if the benefit is the same for all mammograms. The average benefit of a subsequent screen is the inverse of the NNSO.
2. The 5.25 median screens from the trials are responsible for the relative risk reduction (RRR) for repeated screening. We assumed the baseline exam has twice the benefit of a subsequent exam [11, 29, 33].
3. The range is calculated by using interval analysis.