Table 1.

Projected 25-year NNS and additional NNT under different assumptions about the overdiagnosis rate among screen detections (O) and hazard ratios (H ) for disease-specific mortality associated with screening.

		Projections in the absence of competing cause of death
Overdiagnosis rate among screen detections	Hazard ratio for disease-specific mortality associated with screening	Incidence rate of non-overdiagnosed cancers in the screened arm	Disease-specific survival in screened arm in the absence of screening	Disease-specific survival in screened arm in the presence of screening	Recipricol of deaths prevented by screening (NNS)	Overdiagnoses relative to deaths prevented by screening (additional NNT)
O	H	N = S(1−O) + C	P = NR + (1 − N)	PH	1/ (PH − P)	O×S / (PH − P)
0.58	0.80	0.048	0.972	0.977	178.35	6.01
0.58	0.56	0.048	0.972	0.984	80.79	2.72
0.42	0.80	0.054	0.968	0.975	159.48	4.45
0.42	0.56	0.054	0.968	0.982	72.21	2.01
0.23	0.80	0.069	0.960	0.968	126.27	1.69
0.23	0.56	0.069	0.960	0.977	57.11	0.76

		Projections in the presence of competing causes of death
Overdiagnosis rate among screen detections	Hazard ratio for disease-specific mortality associated with screening	Cumulative incidence of disease-specific mortality in screened arm	Cumulative incidence of disease-specific mortality in control arm	Recipricol of deaths prevented by screening (NNS)	Overdiagnoses relative to deaths prevented by screening (additional NNT)
O	H	Ms	Mc	1/(Mc − Ms)	O×S/(Mc − Ms)
0.58	0.80	0.015	0.019	262.49	8.85
0.58	0.56	0.011	0.019	118.76	4.00
0.42	0.80	0.018	0.023	219.83	5.36
0.42	0.56	0.013	0.023	99.96	2.44
0.23	0.80	0.022	0.027	185.95	2.48
0.23	0.56	0.015	0.027	83.92	1.12