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

From: What is the point: will screening mammography save my life?

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.