Watchdog examines bleeds caused by blood thinners

THE medical watchdog is investigating why blood thinners are causing dangerous side effects in some patients.

A group of medicines known as direct oral anticoagulants are taken by around 1.5 million people in Britain to help prevent blood clots and protect them against strokes.

Yet between 2 and 5 per cent of people on the drugs suffer dangerous bleeds, which can lead to hospitalisation and even death.

The Medicines and Healthcare Products Regulatory Agency (MHRA) has launched a study into whether genetics makes some patients more vulnerable, in the hope that in future people could be screened for potential side effects.

The MHRA has begun recruiting patients and is asking anyone who has experienced excessive bleeding after taking direct oral anticoagulants to report it to the Yellow Card scheme. They may be contacted for a genetic sample. Examples of the drugs include rivaroxaban, dabigatran, apixaban and edoxaban.

Dr Alison Cave, MHRA chief safety officer, said: “We know that prescribing is increasing, but we know for some individuals the drugs are associated with excessive bleeding. The long-term goal for us is to identify patients most at risk of harm from side-effects with a particular medicine due to their underlying genetic make-up, and avoid them suffering from that harm.

“It’s quite exciting for me, because it moves us to more proactive vigilance, rather than mitigation and that’s where we would like to be, preventing these reactions ever from happening rather than detecting them after they happen.”

The investigation is part of the Yellow Card Biobank, a pilot launched last year which is already looking at the genetic reasons why the gout treatment allopurinol causes severe skin reactions in some people.

Side-effects from drugs account for one in every 16 hospital admissions in Britain, and cost the NHS more than £2billion each year. But trials are often too small to pick up adverse reactions, particularly when they are driven by rare genetic mutations.

The drugs are often prescribed to people at risk of a stroke, or with an abnormal heartbeat and have largely replaced warfarin because they are simpler to administer. Excessive bleeding caused by the drugs can usually be reversed in hospital, but it can prove fatal.

The MHRA is working alongside Genomics England on the project, which is hoping to recruit 200 people who have suffered a bleed. Results are expected in March 2025.