This is a plain English summary of an original research article
Risk of stroke and heart attack decreases with lower systolic blood pressure such as 120 mmHg and 130 mmHg compared with a higher level of 160 mmHg. Lower target pressures are associated with an increased risk of serious adverse events like fainting. The target with the best balance between efficacy and safety in this research seems to be 130 mmHg.
National guidelines mostly recommend a systolic target of 140 mmHg. Recent trials have assessed the value of a lower 120 mmHg target, with mixed findings. This review aimed to address this uncertainty by pooling 17 trials comparing different blood pressure targets.
The findings from this network meta-analysis cannot be applied to specific population groups, such as those with diabetes. For an individual, the absolute benefits will also depend on the assumed risk before treatment, taking into account all other factors, such as lipid levels, age and smoking.
These results may inform further discussion and NICE guideline updates. The balance of benefits and harms of lower blood pressure targets is likely to be an important determinant.
Why was this study needed?
More than one in four UK adults has high blood pressure (hypertension). Hypertension is estimated to account for 12% of all visits to GPs in England. Associated diseases, like heart disease and stroke, are estimated to cost the NHS over £2 billion every year.
There is uncertainty over the blood pressure target which gives the best balance between benefits and side effects. Most national guidelines recommend an upper (systolic) target of <140mmHg but results from several recent trials have been conflicting. The SPRINT trial found a lower target of 120 mmHg improved overall cardiovascular risk in people without diabetes, while the ACCORD BP trial found this lower target gave little benefit for people with diabetes.
This study aimed to combine the results of trials to shed light on the optimal systolic blood pressure target.
What did this study do?
This systematic review identified 17 randomised controlled trials that compared blood pressure targets in a total 55,163 adult patients.
The authors defined five systolic blood pressure targets, ranging from <120 mmHg to <160 mmHg with three intermediate groups separated by 10 mmHg. The researchers performed network meta-analyses comparing each target with the upper threshold of <160 mmHg within and across trials.
The trials included a heterogeneous population, and it was not possible to take account of level of cardiovascular risk at baseline. The results are therefore not focused on specific groups, such as the elderly or people with diabetes. An additional limitation is that the review only looks at systolic blood pressure alone, not together with diastolic pressure.
What did it find?
- A target of 120 mmHg reduced the risk of stroke compared with 160 mmHg, but this was on the borderline of statistical significance (rate ratio [RR] 0.54, 95% confidence interval [CI] 0.29 to 1.00). There was no significant difference when comparing the two lowest pressure target groups (120 mmHg vs. 130 mmHg: RR 0.88, 95% CI 0.51 to 1.52).
- The lower target of 120 mmHg also reduced risk of myocardial infarction, but again this was on the threshold of statistical significance (RR 0.68, 95% CI 0.47 to 1.00). For myocardial infarction , 120 mmHg was ranked as the most likely optimal target, followed by 130 mmHg.
- Systolic blood pressure target had no effect on outcomes of all-cause death, cardiovascular death and heart failure. The authors state that point estimates of relative risk favoured targets of 120 mmHg and 130 mmHg, but there were no statistically significant findings.
- Serious adverse effects like low blood pressure, fainting and slow heart rate, were more frequent with the lower target of <120 mmHg compared with higher targets of 140 mmHg (RR 2.12, 95% CI 1.46 to 3.08) and 150 mmHg (RR 1.83, 95% CI 1.05 to 3.20).
- A systolic blood pressure target of <130 mmHg was assessed to have the best balance of efficacy and safety.
What does current guidance say on this issue?
The NICE guideline on hypertension, updated in 2016, recommends people aged under 80 years aim for a clinic systolic blood pressure below 140 mmHg (140/90 mmHg) and ambulatory or home systolic pressure below 135 mmHg (135/85 mmHg). People aged 80 years and over are recommended to aim for a clinic systolic blood pressure below 150 mmHg (150/90 mmHg) and ambulatory or home systolic pressure below 145 mmHg (145/85 mmHg).
The diabetes guideline recommends people with diabetes maintain blood pressure below 140/80 mmHg or below 130/80 mmHg if there is kidney, eye or stroke damage. The European Guidelines recommend similar targets.
What are the implications?
A lower systolic blood pressure target of 130 mmHg may benefit cardiovascular health.
A survey by NICE in 2015 shows how hypertension is being managed nationally. More than 85% of patients aged 80 years or over with treated hypertension had their previous blood pressure reading at 150/90 mmHg or below. These findings may inform discussion of whether a lower systolic blood pressure target could further reduce cardiovascular events and NHS costs.
However, the balance of benefits against harms of lower blood pressure targets is likely to be an important determinant. This balance should be discussed with patients. Commissioners will also be interested in the health system cost and cost-effectiveness of lowering the targets.
Citation and Funding
Bangalore S, Toklu B, Gianos E, et al. Optimal Systolic Blood Pressure Target After SPRINT: Insights from a Network Meta-Analysis of Randomized Trials. Am J Med. 2017;130(6):707-19.
No funding information was provided for this study.
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