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People of all ages who have even slightly raised blood pressure should be offered treatment with antihypertensive drugs (to lower blood pressure). New research found that the drugs reduce the risk of cardiovascular events, such as heart attack or stroke, in all ages up to 85. The trend continued in the over 85s but was less certain because there were fewer people of this age in the study.
High blood pressure (hypertension) is common. In the UK and Europe, the treatment target (the blood pressure level that treatment aims for) is higher in older age groups. Before this review, it was uncertain whether people over 70 benefit from starting, or continuing, with antihypertensives if their blood pressure is not markedly high.
This large analysis investigated whether antihypertensives protect against cardiovascular diseases in adults of different ages. Researchers pooled data from studies including more than 350,000 people, and found that these drugs reduced the risk of cardiovascular events – regardless of age – in people with blood pressure that was even slightly raised.
The review concluded that antihypertensives benefit adults of all ages with even slightly raised blood pressure. Age-based thresholds should be removed from European and UK guidance, the researchers say. However, more research is needed in people over 85.
What’s the issue?
High blood pressure increases the risk of cardiovascular events such as stroke and heart attack. Drugs that lower blood pressure (antihypertensives) reduce the risk. Around 1 in 3 adults in the UK has high blood pressure. Many are unaware of their condition because symptoms are rarely noticeable; most people only find out when they have their blood pressure checked.
Ideal blood pressure is generally between 90/60 and 120/80 mmHg. The higher number (systolic pressure) is the force at which the heart pumps blood around the body - and is the number considered in this research. The lower number (diastolic pressure) is the resistance to blood flow in the vessels.
Different age groups have different blood pressure targets. For example, UK guidance recommends treatment for people older than 80 years only if they have markedly increased blood pressure, of 150/90 mmHg or higher.
Researchers showed recently that even small reductions (of 5 mmHg) in systolic blood pressure reduced cardiovascular risk, regardless of whether blood pressure was normal or high. In this analysis, the same team explored whether antihypertensive drugs protect against cardiovascular diseases in people of all ages.
Data was collected from more than 50 studies that randomly allocated people to receive various antihypertensive treatments or dummy (placebo). The studies included 358,707 people aged 21 – 105 (65 years on average).
The researchers looked at people’s age and their blood pressure (which ranged from less than 120/70 mmHg to 170/110 mmHg) at the beginning of a study. They looked at the link with cardiovascular events (stroke, heart attack, heart disease or heart failure) and whether the person died.
The researchers found that, in all age groups, reducing blood pressure reduced cardiovascular events. The reductions did not depend on blood pressure before treatment. Whatever the initial blood pressure, the risk of cardiovascular events was reduced as the systolic blood pressure was lowered.
For each 5 mmHg reduction in systolic blood pressure, cardiovascular events were reduced by:
- 18% in the under 55s
- 9% in groups aged 55-64, 65-74, and 75-84 years
- 1% in those aged 85 and older.
These figures show that the percentage reduction in cardiovascular events was highest in the under 55s. But these events are rare in younger people, which means this percentage reduction translates into fewer events prevented. Older people are generally at higher risk of cardiovascular events. With 4 years' treatment (on average) in this analysis, despite the smaller percentage reduction, more events were prevented in older people.
Why is this important?
Experts around the world disagree on whether people over 70 should be prescribed antihypertensives. Guidelines differ; in Europe blood pressure targets vary by age, while in the United States, they do not. This research shows that age should not determine whether treatment with antihypertensives is started.
The researchers say that antihypertensives are effective into old age. Currently, blood pressure of 120/80 mmHg is considered normal. This analysis suggests that anyone whose blood pressure is above 120/70 mmHg should consider treatmentto reduce their cardiovascular risk. Age-related blood pressure thresholds should be removed from guidelines, the researchers say. As long as the drugs are well tolerated, older people should take them to prevent cardiovascular events.
Cardiovascular events are more common in older people. This means that, even though reducing blood pressure in older people prevented a smaller fraction of events, more were prevented in older than in younger people.
This study included fewer over 85s than in the younger age groups. The findings suggest that people over 85 with slightly raised blood pressure also benefit from antihypertensives but the evidence in this age group is less robust.
More research is needed in people aged 85 and older, the researchers say, and in some other groups such as people with multiple long-term conditions, and those who are frail. These populations could respond differently to antihypertensives or have different risks of cardiovascular events.
The researchers hope that their work will be used as a basis for discussion around whether people should take antihypertensives. They hope that UK guidance will change in the next few years to reflect their findings.
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This NIHR Alert is based on: The Blood Pressure Lowering Treatment Trialists’ Collaboration. Age-stratified and blood-pressure-stratified effects of blood-pressure-lowering pharmacotherapy for the prevention of cardiovascular disease and death: an individual participant-level data meta-analysis. Lancet 2021;398:1053-64
Another paper by the same group: The Blood Pressure Lowering Treatment Trialists’ Collaboration. Pharmacological blood pressure lowering for primary and secondary prevention of cardiovascular disease across different levels of blood pressure: an individual participant-level data meta-analysis. Lancet 2021;397:1625-1636
Funding: This research was funded by the British Heart Foundation, the NIHR Oxford Biomedical Research Centre, and the Oxford Martin School.
Conflicts of Interest: The study authors declare no conflicts of interest.
Disclaimer: NIHR Alerts are not a substitute for professional medical advice. They provide information about research which is funded or supported by the NIHR. Please note that views expressed in NIHR Alerts are those of the author(s) and reviewer(s) and not necessarily those of the NHS, the NIHR or the Department of Health and Social Care.