Millions of adults in England are unaware they have hypertension, while half of those treated by a GP do not have it under control.
The study found that 59 per cent of people with high blood pressure were undiagnosed, raising their risk of stroke, heart attack and early death.
Among people who had been diagnosed and said they were taking blood pressure-lowering medication, 50 per cent still had uncontrolled high blood pressure.
Wenyu Liu, a medical statistician at Oxford Population Health and lead author of the study, said: “While hypertension is largely a ‘silent killer’, the current approach to detecting and treating high blood pressure is not fit for purpose.
“Our study highlights the prevalence of hypertension across demographics. This underscores the need for population-wide prevention strategies alongside targeted treatment for people at high cardiovascular risk.”
Researchers at Oxford University analysed data from 1.4 million adults enrolled in the Our Future Health programme between 2022 and 2025.
High blood pressure was defined as a reading of 140/90 mmHg or above.
The researchers calculated that 37 per cent of adults in the study had high blood pressure, with about six in 10 unaware of it.
Hypertension was almost 50 per cent more common among men than women, affecting 42 per cent of men and 29 per cent of women across all ages. It was also more common among older people.
Detection and control of high blood pressure improved substantially during the 2000s, researchers said, but progress had plateaued since around 2011.
They also found signs of worsening trends following the Covid-19 pandemic, which they suggested could be related to disruption to healthcare services.
The large number and proportion of people with undiagnosed hypertension was the study’s most striking finding, according to the researchers.
They also highlighted that only half of adults with high blood pressure who were receiving treatment through a GP had their condition adequately controlled.
Dr Iain Turnbull, a GP, deputy chief medical officer at Our Future Health and clinical research fellow at Oxford Population Health, said it was not clear why 50 per cent of patients who said they were taking blood pressure-lowering medication had uncontrolled hypertension.
“Blood pressure varies considerably between people, and some people need changes in dose or two or more different medicines before it is brought under control.
“Other health conditions and medications can affect blood pressure, too.
“There are also practical and social factors: side effects, complicated treatment regimens and competing health or life pressures can make medicines difficult to take consistently. Weight, diet, salt intake, alcohol and physical activity can also influence blood pressure.
“So a high reading can have many explanations and shouldn’t be seen simply as a reflection of what an individual patient or healthcare professional has done.”
The researchers did not have prescribing records to independently confirm medication use, and a blood pressure measurement on one day may not represent a person’s usual blood pressure.
Turnbull added: “Even with those caveats, I wouldn’t regard 50 per cent as a satisfactory figure. Persistently high blood pressure increases the risk of stroke and heart disease, and bringing it under control reduces that risk.”
Professor Bryan Williams, chief scientific and medical officer at the British Heart Foundation, said the study “paints a concerning picture of the scale of undetected high blood pressure in the UK, and the challenges of keeping blood pressure under control in those already receiving treatment”.
He added: “Better detection and treatment could help tens of thousands of people to avoid a preventable heart attack and stroke.
“But to achieve this, we will need to rethink how we identify, treat and support those at risk so that blood pressure checks and effective treatment can benefit everyone.”
