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Consideration of wider risk factors may be important when treating adults with low-risk mild hypertension (raised blood pressure).
A large NIHR-funded UK study compared rates of mortality and risk of cardiovascular disease between patients who received antihypertensive treatment and those who did not. There was an increased risk of adverse effects, like low blood pressure. It found no evidence to support starting drug treatment for adults of low-cardiovascular risk with mild hypertension.
This is in line with current NICE guidelines which suggest offering lifestyle advice on several occasions before looking for pharmacological treatment in mild hypertension.
There is an ongoing debate about treatment thresholds for mild hypertension, but overall, considering cardiovascular risk and addressing unhealthy lifestyle habits may be more important than tackling raised blood pressure alone. This study is a helpful contribution to a wider debate on avoiding over-treatment and shows the value of large patient datasets to address uncertainties.
Why was this study needed?
Hypertension is the third biggest risk factor for all disease in the UK, closely following smoking and poor diet. It costs the NHS over £2.1 billion every year.
Clinical guidelines for the treatment of hypertension across the world are inconsistent. American College of Cardiology/American Heart Association (ACC/AHA) guidelines recommend the use of antihypertensive drug treatment in high-risk patients with a blood pressure of 130/80mmHg or higher, or for individuals with blood pressure of 140/90mmHg or higher, regardless of cardiovascular risk. However, the recommendations for the use of antihypertensives in patients with low cardiovascular risk has sparked debate, as there is a lack of clinical trial evidence to support the initiation of drug treatment for mild hypertension. This UK study aimed to address this gap.
What did this study do?
This retrospective longitudinal cohort study examined electronic health record data from the Clinical Practice Research Datalink of 38,286 low-risk adults (average age 55) with mild hypertension. It compared rates of mortality and risk of cardiovascular disease between two groups: patients who received antihypertensive treatment and those who did not.
Mild hypertension was defined as three consecutive blood pressure readings of 140/90-159/99mmHg within 12 months. The study defined cardiovascular risk by comorbidities rather than cardiovascular risk score because of concerns about missing data in the records. People with previous history of cardiovascular disease or cardiovascular risk factors were excluded.
Patients were analysed in the two groups regardless of whether or not they subsequently started or stopped treatment during follow-up. Average follow-up was only 5.8 years, and a longer follow-up could have been useful.
What did it find?
- Overall, a total of 1,641 deaths occurred during the 5.8 years of follow-up: 4.49% of those on antihypertensives and 4.08% of those not on treatment. No significant difference was observed between the groups (hazard ratio [HR]: 1.02, 95% confidence interval [CI] 0.88 to 1.17).
- Similarly, no significant associations were found between antihypertensive treatment and cardiovascular disease (HR: 1.09, 95% CI: 0.96 to 1.25).
- The study did, however, find that treatment was linked to an increased risk of adverse events such as low blood pressure (HR: 1.69, 95% CI: 1.30 to 2.20) and fainting (HR: 1.28, 95% CI: 1.10 to 1.50).
What does current guidance say on this issue?
NICE’s 2011 guidelines on adult hypertension recommend using a formal method of estimating cardiovascular risk to discuss both prognosis and healthcare options for people with hypertension. This applies for not just raised blood pressure but also other modifiable risk factors.
The guidelines recommend offering lifestyle advice initially and then periodically before looking for pharmacological treatment in mild hypertension.
The NICE guideline Hypertension in adults: diagnosis and management is presently in development, with an expected publication date of August 2019.
What are the implications?
This study found no evidence to support recommendations outlined in US (ACC/AHA) clinical guidelines for the initiation of treatment in low-risk patients with mild hypertension.
The findings suggest that overall cardiovascular risk may be more important than raised blood pressure alone and consideration of wider risk factors may be needed instead of treating isolated mildly raised blood pressure.
As such, it does support the current NICE approach which suggests looking for non-pharmacological treatments such as lifestyle changes first in mild hypertension.
Citation and Funding
Sheppard JP, Stevens S, Stevens R. Benefits and harms of antihypertensive treatment in low-risk patients with mild hypertension. JAMA Intern Med. 2018;178(12):1626-34.
This project was funded by a grant from the National Institute for Health Research (NIHR-RP-R2-12-O15) and the Medical Research Council (MRC) Strategic Skills Postdoctoral Fellowship.
Bibliography
Blood Pressure UK. Blood pressure facts and figures. London: Blood Pressure Association; 2008.
NICE. Hypertension in adults: diagnosis and management. CG127. London: National Institute for Health and Care Excellence; 2011.
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