HUNDREDS of thousands of people could be put on blood pressure drugs to prevent heart attacks and strokes under new advice from the NHS watchdog.

It supports reducing the threshold at which beta blockers and other medications are prescribed.

The draft guideline recommend them for patients with less severe hypertension, or stage 1, whose estimated 10 year risk of cardiovascular disease is at least ten percent.

It is the biggest change since 2011, which had a threshold of 20 percent. In the UK, at least a quarter of adults have high blood pressure.

Dr Anthony Wierzbicki, chair of the NICE (National Institute for Health and Care Excellence) panel, said: "Many people with high blood pressure don't actually know they have it because it rarely causes any noticeable symptoms.

"However, it is by far the biggest preventable cause of death and disability in the UK through strokes, heart attacks and heart failure.

"A rigorous evaluation of new evidence has resulted in updated recommendations around when to treat raised blood pressure that have the potential to make a real difference to the lives of many thousands of people with the condition."

Blood pressure pills such as ACE inhibitors and beta blockers cost as little as 10p a day while diseases caused by hypertension are estimated to cost the NHS over £2bn every year and account for 12 per cent of all visits to GPs in England.

Stage 1 is defined as a clinic blood pressure reading of 140/90 mmHg (millimeters of mercury) or higher, or a daytime average or home blood pressure monitoring average of 135/85 mmHg or higher.

The numbers show the pressure in your arteries when your heart is forcing blood through them, or relaxing, respectively.

The higher they are, the harder your heart has to work, forcing the blood through arteries which may have narrowed or become stiff. This can trigger a heart attack or stroke.

Stage 1 is diagnosed when there is no simple identifiable cause of the raised blood pressure. It may be linked to obesity, diet such as too much salt, physical inactivity or genetic inheritance.

Around 450,000 men and 270,000 women would fall into the category of having it with a CVD (cardiovascular disease) risk of between 10 and 20 percent.

It supports the direction of the NHS Long Term Plan and CVD ambitions to improve outcomes, including preventing strokes and heart attacks, through better detection and treatment.

Dr Wierzbicki, a heart disease specialist at Guys and St Thomas' Hospital, London, said: "The guideline effectively shifts the focus to earlier intervention with lifestyle or drug treatment because this may slow the age-related deterioration of blood pressure.

"This would keep people well for longer and reduce the long-term need for multiple medications.

"It unifies and simplifies the advice given to GPs in implementing the NHS Health Check and it supports the NHS Long Term Plan's aim to improve chronic disease prevention.

"The guideline also places a greater emphasis on achieving and maintaining blood pressure targets as many people with high blood pressure are undertreated."

But predicting the impact is hard. There is variability in how the 2011 advice is being implemented in practice.

Some estimates suggest around 50 percent of people in the lower threshold group are already being treated with blood pressure lowering drugs.

The draft guideline also considered new studies suggesting people with blood pressure below 140/90mmHg might also benefit from medication.

However, some of these studies, which formed a key part of the evidence reviewed in other recent international hypertension guidelines, were difficult to interpret.

They recruited people with raised blood pressure who had increased CVD risk, and those who had other CVD risk factors such as established blood pressure-related organ damage from previous CVD, or chronic kidney disease.

Therefore, these studies could not be directly used to inform the recommendations in this draft guidance.

Professor Jamie Waterall, National Lead for Cardiovascular Disease Prevention at Public Health England, said: "High blood pressure is the country's leading cause of heart attacks and strokes yet millions remain undiagnosed.

"Diagnosing high blood pressure earlier and managing it in line with NICE guidance will save thousands of lives and years spent in ill-health.

"That's why we've set new national ambitions to improve the detection and management of high blood pressure within the next decade.

"If you're over 40, getting your free NHS Health Check is a simple way to find out your blood pressure as well as your risk of other serious conditions."

In 2015, it was reported that, in England, high blood pressure affected more than one in four adults (31 per cent of men; 26 per cent of women) - around 13.5 million people - and contributed to 75,000 deaths.

The clinical management of hypertension accounts for 12 per cent of visits to primary care and up to £2.1 billion of healthcare expenditure.

Over the last decade progress has been made to improve the diagnosis and management of hypertension: The average blood pressure in England has fallen by about 3 mmHg systolic and the proportion of adults with untreated high blood pressure has decreased.

However, the Public Health England Blood Pressure Action Plan (Tackling high blood pressure: from evidence into action, 2015) called for further measures to reduce average blood pressure by a further five mmHg through improved prevention, detection and management.

The draft guideline is open for public consultation until 23 April 2019. Final guidance is expected to be published in August 2019.