59% of People With This Serious Heart Health Risk Go Undiagnosed, Study Finds

In 2024, an estimated 1.4 billion people worldwide aged between 30 and 79 had high blood pressure, according to the World Health Organization. And that number could be even higher, because the condition often comes with no obvious symptoms – meaning people can have it without realising it.

In fact, a new study published in the journal BMJ Public Health looked at just how prevalent sneaky hypertension can be, and the results are jarring: over half of participants had high blood pressure without knowing it.

In the study, researchers analysed the health data of 1.4 million adults in England to determine the prevalence of hypertension, which they defined as a systolic blood pressure (the first number in a reading) of 140mmHg or higher, a diastolic blood pressure (the second number) of 90mmHg or higher, or self-reported use of prescription blood pressure medication.

They discovered 37 per cent of participants met the criteria for high blood pressure – and the condition became more likely with age, and was more common in men and in people with a higher body mass index. Perhaps even more staggering? Nearly 59 per cent of the people with high blood pressure didn’t know they had the condition. And just over 50 per cent of hypertensive people who were on medication still didn’t have their numbers under control.

The data is unsettling, but heart health experts aren’t really surprised by it. Here’s what they have to say about the findings, and how to be vigilant about maintaining healthy blood pressure.

Why does high blood pressure go undetected?

As we mentioned, elevated blood pressure typically doesn’t manifest as physical symptoms that ‘hurt’ people who have it, explains Dr Lily Johnston, a vascular surgeon and author of the forthcoming book Disconnected. “You can live at 150/95 for years and feel fine,” she explains. And symptoms that could be caused by high blood pressure, like headaches, anxiety or dizziness, are nonspecific, so people often attribute them to other causes.

Why don’t symptoms show? “Our bodies are remarkably good at adapting to conditions that slowly damage blood vessels, so even as the damage builds, we feel fine,” explains Dr Heather Gosnell, a physician and plant-based health coach. “And a single elevated reading is often brushed off as nerves.” This is often referred to as white coat syndrome, where a patient’s blood pressure is only elevated at the doctor’s office.

There is also a lack of awareness and education about the importance of regular check-ups and at-home blood pressure monitoring, which leaves plenty of room for the problem to go unnoticed.

Then, even for people who do monitor at home, there’s also the issue of incorrectly using at-home blood pressure devices, says Dr Amit Blumfield, a cardiologist.

For an accurate blood pressure reading, keep these steps in mind:

• Take your reading when your bladder is empty and you don’t need to pee.
• Make sure you’re using the correct blood pressure cuff size for your arm, and that you’re placing it on bare skin.
• Rest quietly for five minutes before taking a reading.
• Maintain proper positioning: sit upright with your back supported and your feet uncrossed on the floor. Uncross your arms and rest the arm you’re using for the reading on a flat surface at the level of your heart.

What about slightly elevated blood pressure? Is that still risky?

It’s certainly not something to ignore. Dr Johnston calls hypertension “a slope that starts much lower than most people think.” The numbers can slowly tick up over time and raise your risk of heart disease. After all, high blood pressure makes your heart work harder to pump blood through your arteries, and that puts stress on the organ and blood vessels over time.

“As a vascular surgeon, I see what years of extra pressure do,” says Dr Johnston. “Over time, the heart wall stiffens, thickens and scars. In my operating theatre, that looks like aneurysms, aortic dissections, kidney failure and vessel blockages. Elsewhere, it’s heart attack, stroke, blindness and, growing evidence suggests, dementia.”

While random, short-lived elevations may happen due to stress or during sleep, “what matters most is the average pressure your arteries live with day to day, and that it comes back down after a spike,” Dr Johnston says.

How to check and maintain healthy blood pressure

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The only way to know if you have high blood pressure is to measure it, our experts say. No other symptoms are reliable. “Feeling stressed or anxious, or having a fast heart rate, doesn’t necessarily mean your blood pressure is up, and you can have a normal reading even when you feel that way,” says Dr Gosnell.

To get an understanding of your levels, Dr Johnston says to take two readings a minute apart, morning and evening, for a week, and bring the log and the cuff to your next doctor’s visit. (Make sure to use a quality at-home monitor – it should be a validated device, she says. You can check yours at stridebp.org.) But if your reading is ever above 180/120, especially if it comes with severe headache, chest pain, shortness of breath, vision changes or confusion, don’t wait – call 000.

Lifestyle choices such as exercise, a balanced diet and maintaining a healthy weight can make a huge difference in keeping your heart working efficiently and your blood pressure in check. “If you already have a diagnosis of hypertension, limiting dietary salt intake as much as possible is important,” says Dr Blumfield. Genetics also play a role, and may require some people to take extra interventions, like medication. “If medications are necessary, take them regularly as prescribed and follow up with your doctor frequently,” Dr Blumfield adds.

Other general ‘healthy’ habits benefit your heart, too. Avoid nicotine, limit or avoid alcohol, and aim for seven to nine hours of sleep each night, Dr Johnston says. “Finding ways to manage stress also matters,” she says. “Work with your doctor to find the right plan for you.”