Blood thinning drugs are preventing 7,000 strokes each year, according to an analysis of general practice records of five million patients from 2000 to 2016 to find out how many people have a diagnosis of atrial fibrillation and how many are receiving treatment to prevent strokes. 

Atrial fibrillation is the most common cause of an irregular heartbeat and five times increases the risk of stroke. To reduce the risk of stroke by around two thirds, patients with atrial fibrillation are given anticoagulant drugs to prevent blood clotting, such as warfarin. 

The new study found that the frequency of diagnosis has increased each year between 2000 and 2016 and reached around 1.2 million in 2016. The researchers also found that, in this same 16-year period, the proportion of patients with atrial fibrillation who were being prescribed anticoagulants more than doubled - rising by 40.1% from 35.4% in 2000 to 75.5% in 2016. 

"We found that in 2000 only 35 percent of people with atrial fibrillation who should be taking anticoagulants were actually prescribed them. By 2016, the situation had changed dramatically and 75 per cent were receiving them, which highlights that GPs have become markedly better at not only identifying patients with atrial fibrillation, but also at treating these patients," said Dr. Nicola Adderley from the University of Birmingham in a statement.  "Furthermore, over the same period, general practitioners also seem to have got better at selecting who should get anticoagulants. 

"The drugs are not recommended for a small minority of younger people with atrial fibrillation whose overall risk of stroke is low and prescribing fell from 20 per cent to 10 per cent in this group."

The authors note this is also a win for NHS general practice. Atrial fibrillation causes about 20,000 strokes in the UK each year but general practice is preventing about 7,000.