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Blood pressure medication could lower heart attack and stroke risk even when blood pressure is not substantially raised.

Drugs to lower blood pressure are still effective at reducing the risk of a heart attack and stroke in old age, even if blood pressure is in an apparently healthy range, according to research funded by the British Heart Foundation and published in The Lancet. The findings are being presented at the European Society of Cardiology (ESC) Congress.

This study, the most detailed of its kind, follows much uncertainty about whether blood pressure medication should be given to elderly patients to reduce their cardiovascular risk when their blood pressure is not substantially raised.

The researchers say that medication to lower high blood pressure should be an important treatment option to lower the risk of heart attack and stroke, regardless of age and across a wide range of blood pressures.

Currently, there are different age and blood pressure cut-off points across the world for which doctors can prescribe blood pressure-lowering drugs to older patients. In the UK, it’s not recommended that patients over 80 years of age start treatment if their blood pressure is below 150/90 mmHg.

Professor Kazem Rahimi (pictured) and his team at the University of Oxford now suggest that age-related blood pressure thresholds should be removed from international guidelines so that older patients are considered for, and can benefit from, the protective effects that blood pressure drugs can offer to the heart.

The researchers studied over 358,707 people aged 21 to 105 years from 51 randomised trials to explore the effects of blood pressure-lowering medication across a range of blood pressure levels on the risk of heart and circulatory diseases.

Participants were separated into five age groups - less than 55 years (42,960 people), 55 to 64 years (128,437), 65 to 74 (128,506), 75 to 84 years (54,016), and 85 years and above (4,788). They were then divided again into seven subgroups based on their systolic blood pressure - the highest number on the blood pressure reading - when they were recruited to the study. Participants were followed-up for an average of four years.

Blood pressure-lowering drugs reduced the risk of a major cardiovascular event (heart attack, stroke, heart failure, or death from cardiovascular disease) across all age groups. In the 75-to-84 year age group, they found that for a 5 mmHg decrease in systolic blood pressure with treatment, the relative risk of having a major cardiovascular event fell by 9 per cent. The risk of coronary heart disease by 9 per cent, stroke and death from cardiovascular disease by 8 per cent and heart failure by 18 per cent. The reduction in risk was not affected by the starting systolic or diastolic blood pressure, down to the lowest blood pressure group of 120/70 mmHg.

Although participants over 85 years of age did not have a significant reduction in relative risk, most likely due to fewer participants in this age group, the absolute risk reduction was generally higher in the older compared to younger age groups. This is expected to be due to a higher percentage of cardiovascular events at the older ages, and suggests those over 85 years could also benefit from blood pressure-lowering for cardiovascular risk management.

Professor Kazem Rahimi, lead researcher of the study at the University of Oxford and consultant cardiologist, said:

“By understanding the relationships between age, blood pressure treatment and cardiovascular effects, we can refine treatment recommendations to better target those who are likely to benefit from blood pressure-lowering medication.

“We believe that age should be no barrier to prescribing effective treatments. We now want to see guidelines across the world being simplified to remove any differing blood pressure thresholds by age, down to a starting blood pressure of 120/70 mmHg.”

Professor Sir Nilesh Samani, Medical Director at the British Heart Foundation, said:

“Our risk of heart attack and stroke increases as we age and this study reinforces the importance of controlling blood pressure to reduce that risk. It shows that there are clear benefits for reducing blood pressure for older patients, even when their levels are not substantially raised.

“This should provide more confidence to doctors in recommending treatment for elderly people with elevated blood pressure. However, the decision to start treatment should always be based on individual circumstances and made jointly with the patient.”

The research was also funded by the National Institute for Health Research (NIHR) Oxford Biomedical Research Centre and the Oxford Martin School, and was conducted by researchers from the Blood Pressure Lowering Treatment Triallists’ Collaboration.