Unlike aspirin blood pressure lowering may not have an immediate effect on risk – but this is unknown
In 100 people
- Without blood pressure lowering 15 may have a stroke over next year
- With blood pressure lowering 12 have a stroke (i.e. a 20% relative risk reduction: 15-12/15 x100% = 20%)
- Of the 15 who would have had a stroke, about 3 avoid a stroke due to taking blood pressure lowering
- 88 did not have a stroke
- Treat 100 patients for a year and benefit 3
- Treat 33 patients for a year with blood pressure lowering and prevent one of them having a stroke (i.e. number needed to treat = 33)
- Each patient has a 1 in 33 chance of benefit from taking blood pressure lowering for the year
Page last reviewed: 22 Apr 2022
