US experts say high blood pressure is overtreated
"Your blood pressure might not be as high as you think: Doctors say some older people may not need medication,” the Mail Online says, reporting on new US guidance for doctors on when to prescribe blood pressure tablets.
The Mail identifies that US experts have recommended adults over the age of 60 should only be prescribed medicine when their blood pressure levels reach at least 150/90mmHg. This, they say is recommended because blood pressure lowering medicines can have side effects such as fainting and falls in older people, and can also have adverse interactions with other drugs.
High blood pressure is a common risk factor for cardiovascular diseases. According to the US guidelines it affects more than two-thirds of adults over 60 years of age – so any change to treatment advice, however small, can affect a lot of people.
Controversy is not unusual in this field, partly because the way doctors approach heart disease is changing. Rather than managing single risk factors such as blood pressure, heart disease management focusses on many factors in a person’s life. These new guidelines – while not directly relevant to how UK doctors treat their patients – emphasise assessing an individual’s overall cardiovascular risk and then treating those at greatest overall risk with more intensive therapy.
It is likely that these new guidelines will reignite the debate.
What is the news based on?
The news is based on new guidance from researchers in the US that has been published open access in the peer reviewed Journal of the American Medical Association (JAMA).
These 2014 US guidelines replace the 2003 US guidelines, and are accompanied in JAMA by several editorials setting the guidance in some context (also available open access).
The new guidelines have focused on thresholds and goals for drug treatment of high blood pressure for adults in the US. In particular, they look at whether certain anti-hypertensive drugs improve health outcomes compared to other drugs.
Based on these research questions, nine recommendations are included in the guidance, of which five are based on blood pressure levels that act as “thresholds” for treatment. It is these thresholds which have been picked up in the UK media.
The five threshold-based recommendations included in the new guideline are:
- People aged 60 years or older should start treatment to lower blood pressure at a systolic blood pressure (SBP) of 150mmHg or higher or diastolic blood pressure (DBP) of 90mmHg or higher (commonly written as 150/90). Doctors should aim to help their patients reach a target of less than 150/90.
- For people younger than 60, treatment should be started at a DBP of 90mmHg or higher, aiming to reduce it to below 90mmHg.
- Alternatively, for people younger than 60, treatment should be started at a SBP of 140mmHg or higher, aiming to reduce it to below 140mmHg.
- For any adult (over 18) with diabetes or chronic kidney disease, treatment should be started at SBP of 140mmHg or higher, or DBP of 90mmHg or higher, aiming to reduce it to below these values.
Importantly, the guideline authors note that recommendations do not apply to people without high blood pressure. This will help to reduce the risk of overtreatment.
How were the guidelines produced?
The new guidelines are based on a systematic review of the evidence. A systematic review combines the findings from studies addressing a particular question or questions. These sorts of reviews usually use set criteria which potential studies for inclusion must meet to be included, such as appropriate study design, and population size. A systematic review is considered one of the strongest forms of evidence. However, the strength of its conclusions are dependent on the quality and homogeneity (similarity) of the studies it pools together.
This systematic review included randomised controlled trials (RCTs) of adults aged 18 or older with high blood pressure and studies with the subgroups including diabetes, heart failure and older adults. RCTs that followed people up for less than a year or with fewer than 2,000 people were excluded from the review. An RCT is the best type of study design to determine whether a treatment is effective. It compares the effects of an intervention with another intervention or control.
Based on findings from this evidence review, nine recommendations were made by a panel of experts from a range of speciality areas such as hypertension, cardiology and primary care (for example GP services). A grading score was given for the strength of each recommendation and prior to publication, the guidelines underwent peer-review.
Why are American medical guidelines in the UK media?
The guideline authors say recommendations in this new guidance differ from recommendations in other currently used guidelines: the new US guidance recommends a target blood pressure of less than 150/90mmHg for people with high blood pressure. This differs from currently recommended blood pressure targets in the UK which are for people under the age of 80 with hypertension to have a blood pressure below 140/90mmHg.
Alongside the published guidelines, three editorial opinion pieces about the guidelines also appear in the latest issue of the Journal of the American Medical Association (JAMA). The authors of one of the editorials say that the revised guidelines have been much anticipated and that some elements may be controversial. One reason for this, noted by the US guideline authors, is that the guideline is not endorsed by any government agency or professional society which, they say, is unusual for these reports. The editorial authors state the main difference between the 2003 guidelines and the new recommendations is whether target blood pressure treatment goals should be more conservative (set higher) in older populations.
What are the UK guidelines for blood pressure treatment?
In the UK, the guidelines for blood pressure management are:
- If your blood pressure is slightly above 130/80mmHg but your risk of cardiovascular disease is low, you should be able to lower your blood pressure by making some changes to your lifestyle.
- If your blood pressure is moderately high (140/90mmHg or above) and you're at risk of cardiovascular disease in the next 10 years, treatment will involve medication and lifestyle adjustments.
- If your blood pressure is very high (180/110mmHg or above) you will need treatment soon, possibly with further tests, depending on your health.
Conclusion
These US derived guidelines do not change how doctors in the UK will help care for people with high blood pressure. But they will provide focus for further expert debate on the issue of treating hypertension in this country.
As the guideline authors note in their conclusion, the guidance does not change the definition of high blood pressure (140/90mmHg or higher), and that the recommendations are not a substitute for clinical judgement (for example, doctors making treatment decisions based on the overall health of their patient and the patient’s preferences). The guideline authors say decisions about care must be carefully considered and incorporate the circumstances of each individual person.
