Key Messages
1. The effect of less aggressive lowering of blood pressure on overall death is unclear. The absolute difference in risks is small, and it is unclear whether these findings would differ for the very elderly, or for those who are frail.
2. For most older adults, relaxing blood pressure targets as one gets older (i.e. letting the blood pressure rise higher than conventional blood pressure targets in younger people) results in an increased risk of stroke, and likely results in an increased risk of serious heart-related side effects, which includes stroke, heart attack (sudden blockage in blood flow to the heart muscle), heart failure (impairment of the heart's ability to pump blood), kidney impairment, and heart-related death.
3. Relaxing blood pressure targets does not likely result in fewer people dropping out of blood pressure target trials due to medicine-related side effects.
4. We need more studies investigating the overall benefits and harms of aiming for lower blood pressure targets in those who are frail, or very elderly.
What is high blood pressure?
As the pressure of the blood within our arteries rises, it increases the risk of stroke, heart attack, heart failure, kidney impairment, and death. At some point, as the pressure rises, these risks are high enough to outweigh any potential risks of treatment. This is when people are considered to have 'high blood pressure', or hypertension.
How is high blood pressure treated?
Weight loss, reducing salt consumption, exercising, and pursuing a Mediterranean diet can all lower blood pressure, but many people also need blood pressure lowering medicine. Current clinical guidelines differ on the best blood pressure target for older adults. The targets range from less than 130/80 to less than 150/90.
For people aged 80 years or older, at least one guideline recommends letting blood pressure rise above 160 mmHg before starting treatment.
What did we want to find out?
Some physicians believe that older adults may be at greater risk of side effects from blood pressure medicine, and we shouldn't try as hard to lower their blood pressure.
We wanted to find out if a higher blood pressure target would reduce risk the same and be safer in older adults than the lower blood pressure targets used for the population at large.
What did we do?
We searched for studies that compared the effect of a higher blood pressure target (less than 150 to 160 mmHg) with a lower blood pressure target (less than 140 mmHg) in people over the age of 65 years. We wanted studies that reported on the number of deaths or other side effects caused by diseases of the heart or the blood vessels, such as heart attack, stroke, or heart failure. We were also interested in other types of health-related side effects.
We only chose randomised studies (where people had the same chance of being put into one of two or more treatment groups) that lasted for at least 12 months.
What did we find?
For this update, we found one new study. We now have four studies trying to answer this question, and a total of 16,732 older adults.
We found there may be little to no difference in the number of overall deaths between those with higher or lower blood pressure targets, who were followed for two to four years.
We found that a lower blood pressure target reduces the risk of stroke better than a higher blood pressure target. It probably reduces serious heart-related events overall (like heart attack, heart failure), and death due to heart problems. A lower BP target probably stops 10 serious cardiovascular events for every 1000 people treated for approximately three years.
Aiming for a higher blood pressure target probably makes little to no difference to the portion of people who dropped out of the studies because of side effects related to their medicine.
What are the limitations of the evidence?
Several factors reduced our confidence in the evidence.
1. People in the studies and their medical providers were aware of which blood pressure target group they were in. This might influence behaviour, or how they report their experience.
2. Not all the studies provided data about everything that we were interested in, including side effects.
3. While the evidence focused on older adults, three of the four studies excluded people who were 80 to 85 years of age or older. Therefore, we do not understand the effects of lower blood pressure targets for the very elderly, or for frail populations.
How up to date is this evidence?
The evidence is up-to-date until June 2024.
When comparing a higher BP target, in the range of < 150 to 160/95 to 105 mmHg, to a lower BP target of 140/90 or lower, over two to four years of follow-up, there is high-certainty evidence that the lower BP target reduces stroke, and moderate-certainty evidence that the lower BP target likely reduces serious cardiovascular events. The effect on all-cause mortality is unclear (low-certainty evidence), and the lower BP target likely does not increase withdrawals due to adverse effects (moderate-certainty evidence).
Although additional research is warranted in those who are 80 years of age and older, and those who are frail (in whom risks and benefits may differ), conventional BP targets may be appropriate for the majority of older adults.
This is an update of the original Cochrane review, published in 2017.
Eight out of 10 major antihypertensive trials in adults, 65 years of age or older, attempted to achieve a target systolic blood pressure (BP) of < 160 mmHg. Collectively, these trials demonstrated cardiovascular benefit for treatment, compared to no treatment, for older adults with BP > 160 mmHg. However, an even lower BP target of < 140 mmHg is commonly applied to all age groups. Yet the risk and benefit of antihypertensive therapy can be expected to vary across populations, and some observational evidence suggests that older adults who are frail might have better health outcomes with less aggressive BP lowering. Current clinical practice guidelines are inconsistent in target BP recommendations for older adults, with systolic BP targets ranging from < 130 mmHg to < 150 mmHg.
The 2017 review did not find compelling evidence of a reduction in any of the primary outcomes, including all-cause mortality, stroke, or total serious cardiovascular adverse events, comparing a lower BP target to a higher BP target in older adults with hypertension. It is important to update this review to explore if new evidence exists to determine whether older adults might do just as well, better, or worse with less aggressive pharmacotherapy for hypertension.
To assess the effects of a less aggressive blood pressure target (in the range of < 150 to 160/95 to 105 mmHg), compared to a conventional or more aggressive BP target (of < 140/90 mmHg or lower) in hypertensive adults, 65 years of age or older.
For this update, Cochrane Hypertension's Information Specialist searched the following databases for randomised controlled trials up to June 2024: Cochrane Hypertension Specialised Register, CENTRAL, MEDLINE Ovid, and Embase Ovid, and the US National Institutes of Health Ongoing Trials Register ClinicalTrials.gov for ongoing trials. We also contacted authors of relevant papers requesting information on further published and unpublished work. The searches had no language restrictions.
We included randomised trials of hypertensive older adults (≥ 65 years) that spanned at least one year, and reported the effect on mortality and morbidity of a higher or lower systolic or diastolic BP treatment target. Higher BP targets ranged from systolic BP < 150 to 160 mmHg or diastolic BP < 95 to 105 mmHg; lower BP targets were 140/90 mmHg or lower, measured in an ambulatory, home, or office setting.
Two authors independently screened and selected trials for inclusion, assessed risk of bias and certainty of the evidence, and extracted data. We combined data for dichotomous outcomes using the risk ratio (RR) with 95% confidence interval (CI). For continuous outcomes, we used mean difference (MD). Primary outcomes were all-cause mortality, stroke, institutionalisation, and serious cardio-renal vascular adverse events. Secondary outcomes included cardiovascular mortality, non-cardiovascular mortality, unplanned hospitalisation, each component of cardiovascular serious adverse events separately (including cerebrovascular disease, cardiac disease, vascular disease, and renal failure), total serious adverse events, total minor adverse events, withdrawals due to adverse effects, systolic BP achieved, and diastolic BP achieved.
With the addition of one new trial, we included four trials in this updated review (16,732 older adults with a mean age of 70.3 years). Of these, one trial used a combined systolic and diastolic BP target and compared a higher target of < 150/90 mmHg to a lower target of < 140/90 mmHg, and two trials utilised a purely systolic BP target, and compared a systolic BP < 150 mmHg (1 trial) and a systolic BP < 160 mmHg (1 trial), to a systolic BP < 140 mmHg. The fourth and newest trial also utilised a systolic BP target, but also introduced a lower limit for systolic BP. It compared systolic BP in the target range of 130 to 150 mmHg to a lower target range of 110 to 130 mmHg.
The evidence shows that treatment to the lower BP target over two to four years may result in little to no difference in all-cause mortality (RR 1.14, 95% CI 0.95 to 1.37; 4 studies, 16,732 participants; low-certainty evidence), but the lower BP target does reduce stroke (RR 1.33, 95% CI 1.06 to 1.67; 4 studies, 16,732 participants; high-certainty evidence), and likely reduces total serious cardiovascular adverse events (RR 1.25, 95% CI 1.09 to 1.45; 4 studies, 16,732 participants; moderate-certainty evidence). Adverse effects were not available from all trials, but the lower BP target likely does not increase withdrawals due to adverse effects (RR 0.99, 95% CI 0.74 to 1.33; 3 studies, 16,008 participants; moderate-certainty evidence).