According to the National Institute for Health and Care Research (NIHR, 2022), it is important for people of any age with even a slightly raised blood pressure to have timely access to anti-hypertensive medication. Recent research published in The Lancet found that these medications can reduce risk of myocardial infarction and stroke in any age up to 85 years old, with the trend continuing above this age, although it is difficult to ascertain outcomes because of the limited sample in this age category.
Hypertension is common in the UK and around the world, particularly in western developed countries with higher rates of poor diets full of saturated fats and salt, and sedentary lifestyles. Hypertension is also common in Asian and African demographics. Hypertension raises the risk of cardiovascular events, and antihypertensives can considerably reduce the risk of such events. The NIHR (2022) reports that one in three adults in the UK has hypertension, with many being completely unaware of their condition because the symptom itself, high blood pressure, is not noticeable. However, the problem is noticeable once a cardiovascular event has occurred — something that in part happens as a result of hypertension. If surveillance of blood pressure is regularly carried out, then the GP surgery might well be where the problem is picked up on.
The ideal blood pressure should be between 90/60 and 120/80 mmHg. The systolic blood pressure represents the pressure at which the blood is pushed around the body by the heart, and the diastolic is representative of the resistance to blood flow in the vessels (NIHR, 2022). This measurement is so important that even 5 mmHg makes a big difference.
The first study
The Blood Pressure Lowering Treatment Trialists' Collaboration (2021a) reported from their large-scale study that a 5 mmHg reduction of systolic blood pressure reduced the risk of major cardiovascular events by 10%, regardless of any pre-existing cardiovascular disease, and this applied even to normal or the upper range of normal blood pressure values.
The researchers found that a fixed degree of pharmacologically maintained blood pressure lowering is effective for both primary and secondary prevention of major cardiovascular dis-ease, even at levels that would not usually be considered as requiring any kind of antihypertensive treatment. The study was large, improving its reliability through its sample size of 358 707 people (aged between 21 and 105 years). For every 5 mmHg reduction in systolic blood pressure, cardiovascular events were found to have been reduced by 18% of anyone over the age of 55 years; by 9% in age groups between 55 and 84 years; and by 1% in those aged 85 years and older (The Blood Pressure Lowering Treatment Trialists' Collaboration, 2021a). However, it is the older population that suffers more of these types of events, and therefore despite the reduction of risk being so significant in the younger age group, they are far less at risk. This means that the reduction in events still equates to fewer events because of the proportion of people aged under 55 experiencing cardiovascular problems. The 1% reduction appears low but translates into a higher number of cardiovascular events prevented, in an age group that suffers many. This is important as there is often disagreement about the treatment being given to people with hypertension who are over the age of 70 years. In the US, offering antihypertensives to those over 70 years of age is currently not recommended, and targets differ per age group in Europe (NIHR, 2022). The research by The Blood Pressure Lowering Treatment Trialists' Collaboration (2021a) on both the effectiveness of antihypertensive medication and then the effectiveness in different age ranges of antihypertensive medication points to the use of antihypertensives being important no matter the person's age.
The second study
Shortly after their initial study, The Blood Pressure Lowering Treatment Trialists' Collaboration (2021b) published their results of a meta-analysis. They found that blood pressure reduction is effective across a wide range of ages, and that there was no evidence to suggest that relative risk reductions for prevention of major cardiovascular events vary according to the baseline systolic or diastolic blood pressures, which are currently varied according to target blood pressure per age range in European recommendations.
They also found no evidence to indicate that treatment could increase mortality in any age group. However, they did note that more research would be needed in the oldest age range of over 85s, as the sample was too small, and cardiovascular events in this smaller sample were too few to draw proper conclusions. The team commented that usually the increase in systolic blood pressure has been deemed essential as the body ages, to maintain coronary and cerebral perfusion. However, in remote rural areas, this blood pressure does not increase with age, suggesting that it is not a natural or essential process. It should therefore not be regarded as something necessary and to avoid treating. The Collaboration's research has shown that even the smallest reduction in blood pressure, and use of antihypertensive medication for normal, high normal or high blood pressure across any age group, is effective at avoiding major cardiovascular events.
The National Institute for Health and Care Excellence (NICE, 2019) does not currently recommend treatment for people aged over 80 years if their systolic blood pressure is less than 150 mmHg. Guidance is similar across Europe and the US. There are restrictions on the provision of antihypertensive medication for those with what would be deemed a raised blood pressure in the lower age ranges.
The sample in The Blood Pressure Lowering Treatment Trialists' Collaboration (2021b) was large (54 016 people aged 75–84 years), and under 5000 participants in the over 85s group, although a rate of 1000 cardiovascular incidents. The difference in risk reduction between age groups may account for the fact that the under 55s often have fewer comorbidities, and that a single risk-factor modification would therefore have a greater effect on cardiovascular disease prevention in this group. There would be fewer risk factors to manage and thus a greater likelihood of effectively managing the one, while in older age groups, there is a complex array of risk factors for a cardiovascular event. However, the authors recommended that their results be treated with caution with regard to the possibility of overinterpreting the results through the assumption that absolute risk reductions reported are fixed. Estimates of risk are proportional effects, with absolute risk differences only being useful for the internal comparisons of effect sizes across the data. The authors highlighted that the risk reduction in the older group appears to be low but may be higher and should be treated as such, in relation to their explanation regarding risk data reporting.
The cardiovascular outcomes measured by the collaboration were stroke, heart failure, ischaemic heart disease and cardiovascular death, as well as the effects on all-cause death, with the intent to inform decision-making for blood-pressure-lowering pharmacotherapy across age ranges (The Blood Pressure Lowering Treatment Trialists' Collaboration, 2021b).
It has previously been reported that low blood pressure may be linked with cognitive dysfunction in older people although The Blood Pressure Lowering Treatment Trialists' Collaboration (2021b) discusses that this is highly likely to be because of reverse causation. Therefore, they are not of the opinion that blood pressure-lowering medication should be avoided in older age groups.
The ongoing trial, ‘ATEMPT’ (the Anti-hypertensive Treatment Evaluation in Multimorbidity and Polymedicated patients Trial; ISRCTN17647940) shall address the limitations defined by the current study, and will also investigate treatment effects on some additional patient outcomes.
Conclusion
The Blood Pressure Lowering Treatment Trialists' Collaboration (2021b) concluded that no evidence exists to justify withholding antihypertensive treatment in older adults, even when their blood pressure is not highly elevated. The team noted that pharmacological blood pressure reduction should be considered an important treatment option for the prevention of cardiovascular events, even in people over the age of 80 years, and recommended that guide-lines should be simplified to remove any differing blood pressure targets according to age.