More than half of people living with high blood pressure are unaware they have it - leaving them at increased risk of heart attack, stroke and early death, a study reveals.

Furthermore, only half of patients being treated for the condition by their GP have it under control, according to the analysis of new data by the University of Oxford.

Researchers examined the records of 1.4 million people enrolled in the Our Future Health programme and calculated that more than one-third of adults in England have high blood pressure, with 59 per cent of these unaware of their condition.

Our Future Health is the UK's largest health research programme, and experts hope it will lead to new ways to prevent, detect and treat disease.

The new study, published in the journal BMJ Public Health, looked at people enrolled between 2022 and 2025 with high blood pressure defined as 140/90 mmHg or higher, or who were on blood pressure-lowering drugs.

The results showed that high blood pressure - also known as hypertension - was almost 50 per cent more common in men than women (42 per cent compared to 29 per cent across all ages), and more common in older people.

The authors said current guidelines from the National Institute for Health and Care Excellence (Nice) mean many people with high blood pressure are never picked up, treated, or go on to have good blood pressure control.

Nice recommends measuring blood pressure for a period of time or at home to confirm diagnosis prior to initiating treatment, 'and recommends lifestyle advice before the initiation of treatment', they said.

 The team said: 'These requirements may contribute to a 'leaky cascade of care', with many cases of hypertension remaining undiagnosed and inadequately treated.

'The workload in primary care focusing on clinical management of established diseases leaves few opportunities for disease prevention.'

Furthermore, other evidence suggests even when patients have high blood pressure in an NHS Health Check in their GP surgery, they are not prescribed drugs, researchers said.

They added: 'The 15.3 per cent prevalence of hypertension in those less than 40 years of age is a cause for concern since young adults are ineligible for an NHS Health Check.'

The team said despite substantial improvements in high blood pressure detection and control during the 2000s, progress has plateaued since around 2011, 'with indications of worsening trends following the Covid-19 pandemic, possibly because disruptions to healthcare delivery may have had lasting effects.

'Thus, the current hypertension prevalence levels in England are similar to those observed two decades ago.'

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.'

Iain Turnbull, deputy chief medical officer at Our Future Health, clinical research fellow at Oxford Population Health, and GP, said: 'Many patients with high blood pressure are undetected or are sub-optimally treated.

'There is a need for a more proactive approach to detection of high blood pressure and to consider initiation of treatment based on predicted risk of cardiovascular disease in addition to levels of blood pressure.'

Professor Bryan Williams, chief scientific and medical officer at the British Heart Foundation, said: 'This 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.

'High blood pressure remains the leading modifiable risk factor for cardiovascular disease, linked to around half of heart attacks and strokes in the UK.

'The worrying reality is that millions of people are still living with the condition without knowing it and missing opportunities for early diagnosis and treatment.

'Better detection and treatment could help tens of thousands of people to avoid a preventable heart attack and stroke.'

More than 11 million people in the UK have been diagnosed with high blood pressure by their GP, according to BHF analysis of NHS data.

A spokesman for Nice said: 'The Nice guideline provides a clear blueprint for reducing heart attacks and strokes by improving the detection and treatment of high blood pressure.

'The guideline does not recommend delaying treatment while people try lifestyle changes alone.

'Instead, it supports lifestyle advice alongside medicines where these are needed.'