A large study of about 1.4 million adults in England has found that more than one-third have high blood pressure, while 59% of those affected do not know they have it. The findings underline the scale of an ongoing public-health challenge and the need for earlier detection of a major risk factor for heart disease and stroke.
Researchers from the University of Oxford analysed clinic blood-pressure readings collected through the Our Future Health programme between 2022 and 2025. The study suggests that undiagnosed hypertension is not limited to older adults and that many people already receiving treatment may still have readings above the research threshold.
High blood pressure rises sharply with age
The researchers used World Health Organization criteria to define hypertension. Participants were classified as having high blood pressure if their systolic reading was at least 140 millimetres of mercury, their diastolic reading was at least 90 millimetres of mercury, or they were taking medication to lower blood pressure.
Overall, more than one-third of adults included in the analysis met that definition. The proportion varied significantly by age:
- 15% of adults aged 18 to 39 had high blood pressure.
- The rate increased progressively among older age groups.
- It reached 71% among people aged 80 and over.
After adjusting for age, men were more likely than women to have hypertension, with rates of 42% and 29% respectively.
Why many cases remain undiagnosed
High blood pressure often produces no obvious symptoms, which is why it is frequently described as a “silent killer”. A person may feel well while elevated pressure is gradually damaging blood vessels and increasing the risk of cardiovascular disease.
The study found that 59% of participants identified as having hypertension were unaware of their condition and had not received treatment. That gap means opportunities for lifestyle advice, monitoring and medication may be missed before a serious event occurs.
The researchers said current clinical processes may contribute to some cases being overlooked. Guidance from the UK’s National Institute for Health and Care Excellence generally requires repeated measurements before confirming a diagnosis. Depending on the individual circumstances, clinicians may also recommend lifestyle changes before prescribing medicines.
Those safeguards are intended to support accurate diagnosis and appropriate care. However, the Oxford researchers argue that the findings warrant a review of whether existing approaches identify and manage people quickly enough.
Treatment does not always bring readings below the threshold
Undiagnosed cases were not the only concern. Half of the participants taking at least one blood-pressure-lowering medicine still recorded readings of 140/90 or higher during the study.
This does not necessarily mean that treatment has failed. Blood pressure can vary between readings, and clinical decisions may take account of a person’s wider health, cardiovascular risk, medication tolerance and treatment history. Nevertheless, the result indicates that controlling hypertension remains difficult for a substantial number of patients.
The study points to the importance of regular follow-up, medication reviews and personalised care. It also raises questions about whether treatment decisions should consider a person’s predicted risk of heart and vascular disease, rather than relying only on a blood-pressure measurement.
Younger adults are also affected
Although prevalence was highest among older people, the researchers highlighted the 15% rate recorded among adults aged 18 to 39. This group may have less contact with routine preventive health services and may not consider themselves at risk.
In England, the NHS Health Check programme is aimed at adults aged 40 to 74. The study’s lead researcher, Wenyu Liu, said the results should prompt consideration of how younger adults can be reached earlier, particularly when they have other risk factors for cardiovascular disease.
A more proactive approach could include wider blood-pressure checks in primary care, pharmacies, workplaces and community settings. Any expansion would need to be accompanied by reliable confirmation, clinical advice and access to follow-up treatment.
Why the findings matter beyond England
The research concerns England rather than the European Union as a whole, but its implications are relevant to wider European public-health policy. Hypertension is a common, preventable risk factor across Europe, while health systems face similar challenges in finding people who do not routinely seek medical care.
For Ireland and other European countries, the study reinforces the value of accessible blood-pressure testing and consistent monitoring. It does not establish Irish prevalence, and the English findings should not be directly applied to Ireland without comparable national data. However, the underlying public-health lesson is widely applicable: screening is only useful when people can receive confirmation, treatment and ongoing support.
What happens next?
The Oxford researchers and cardiovascular health experts are calling for stronger prevention and detection strategies. Their proposals include:
- Finding undiagnosed cases through more active community and primary-care testing.
- Improving follow-up for people whose blood pressure remains high during treatment.
- Considering overall cardiovascular risk when deciding how intensively to treat patients.
- Strengthening prevention measures for younger adults as well as older people.
The findings do not themselves change NHS guidance or create a new treatment rule. Any change would require assessment by the relevant health authorities and clinical bodies.
Conclusion
This study shows why high blood pressure remains a serious public-health issue: many people have no symptoms, do not know they are affected, or continue to record elevated readings despite treatment. The central takeaway is clear—earlier checks, accurate diagnosis and sustained follow-up could help reduce avoidable heart attacks and strokes, while policy-makers consider how to reach people before complications develop.
