Table 4

Absolute reduction in myocardial infarctions by aspirin treatment of 100 persons for five years, and NNT, assuming relative risk reduction of 30%; and benefit net of bleeding complications of different severity

Myocardial infarcts prevented		CHD event risk
		0.5%/year			1.0%/year			1.5%/year
		MI prev	NNT		MI prev	NNT		MI prev	NNT
Total	0.75	133		1.50	67		2.25	44
Net of cerebral haemorrhage (0.19)^4-150	0.56	179		1.31	76		2.06	49
Net of major bleeds (0.17)^4-150	0.39	256		1.14	88		1.89	53
Net of non-minor bleeds (0.76)^4-150	−0.20	(500)^4-151		0.55	182		1.30	77

↵4-150 Absolute risk of bleeding complications in 100 persons per five years, assumed constant and independent of CHD event risk.
↵4-151 Number treated for five years to harm one person (NNTH).
MI prev, myocardial infarcts prevented; NNT, number needed to treat for five years.