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
Introduction to blood pressure lowering medication
- Medication to lower blood pressure should be considered for secondary prevention after either ischaemic or haemorrhagic stroke
- The best time to start blood pressure lowering therapy depends on several factors, including the type of stroke (ischaemic or haemorrhagic), and what co-morbidities the patient may have.
- Ongoing research aims to establish whether blood pressure lowering should be started immediately after stroke onset.
- For patients presenting within 6 hours of stroke onset due to intracerebral haemorrhage, acute blood pressure reduction to <140mmHg systolic for the first 7 days is often attempted if BP is >150mmHg systolic.
- Blood pressure is sometimes lowered acutely to facilitate thrombolysis e.g if >180/110mmHg.
- Typically thiazides, e.g. Bendroflumethiazide and/or ACE inhibitors e.g. Lisinopril, are used after stroke, although other classes of blood pressure lowering agents are often used. It is common to need several different drugs to achieve a target blood pressure.
- It is useful to have a working knowledge of their common adverse effects so that if these arise they can be attributed to the correct drug
- A target systolic blood pressure of less than 130mmHg is appropriate for most patients, although there are specific exceptions including severe extracranial vascular disease, or frailty.
- Lifestyle factors, such as reducing salt intake, weight loss, and avoiding excess alcohol also contributes to BP reduction
Reference: Royal college of Physicians Stroke Guidelines (2016).
The Stages of Change model is useful when supporting patients and their families to change lifestyle behaviours that put them at risk of stroke or recurrent stroke, for example:
- Smoking/using tobacco
- Using illicit drugs
- Excessive alcohol consumption
- Unhealthy diet
- Inactive lifestyle
In the late 1970s- and continuing into 1980s- Prochaska and DiClimente developed a ‘stages of change’ theory to explain the processes associated with behaviour change.
They describe a ‘stages of change’ model, which identifies the 6 stages of change:
- Pre-contemplation
- Contemplation/Thinking
- Preparation/Planning
- Action/Making change
- Maintenance or
- Relapse
If healthcare professionals are able to assess and recognise which stage an individual is at, they will be better able to intervene appropriately and effectively.
