A new study from the University of Oxford found that around 15 percent of people aged 40-75 may have undiagnosed hypertension.
Those who may be suffering from the form of high blood pressure may not know, as pressure spikes at night. This could put them at increased risk of cardiovascular diseases including stroke and heart failure.
The researchers have said that 24-hour blood-pressure monitoring has become less frequent since the Covid-19 pandemic began. They also point out that home blood-pressure monitors cannot be used during sleep, meaning that those who spike at night could go undiagnosed.
The study, which was published in the British Journal of General Practice looked at 21,000 patients from 28 GP practices and four hospitals in the Oxford area. Researchers analysed blood pressure spikes and broke patients into three groups.
- 'dippers' - night-time blood pressure is lower than the day-time blood pressure
- 'non-dippers' - blood pressure doesn't change much between day and night
- 'reverse dippers' - day-time blood pressure is lower than the night-time blood pressure
'Dippers' account for most healthy young people, but the researchers found that around 15 percent of the patient population followed the 'reverse-dipper' pattern in which blood pressure rises at night.
Right now, UK NICE Guidelines recommend GPs diagnose the form of high blood pressure based on day-time measurements. However co-author of the study, practising GP, and Doctoral Research Fellow of the University of Oxford, Laura Armitage has said that this should change.
Dr Armitage argues that day-time blood pressure measurements may not detect high blood pressure in high-risk patients who suffer spikes at night.
Professor Lionel Tarassenko, another Co-author and a Professor of Electrical Engineering and founder Director of the Institute of Biomedical Engineering, Department of Engineering Science, University of Oxford, said: "Blood pressure follows a cyclical pattern over 24 hours. Normally, it goes down (or ‘dips’) at night during sleep and then rises after waking.
"For ‘reverse dippers’ (mostly elderly people, sometimes with diabetes or kidney disease), the pattern is reversed: the blood pressure goes up (or ‘reverse dips’) at night, and then decreases after waking."
The researchers conclude that only measuring day-time blood pressure puts all groups other than 'dippers' at risk of undiagnosed hypertension.
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