New test predicts effectiveness of anti-stroke drugs

A new blood test is being made available on the NHS that can predict how patients will respond to taking anti-stroke drugs in the wake of an attack. The technique identifies genetic clues that medication may not be effective, so doctors can prescribe alternatives.

The risk of having a stroke becomes higher as you get older, because arteries naturally become harder and narrower. It’s predicted some 25,000 Brits are genetically predisposed not to respond well to clopidogrel, which is the most common drug used to prevent a stroke.

Genetic markers identifying this group means they can now be given dipyridamole instead, which also thins the blood. These patients don’t have the CYP219 gene, which is responsible for creating enzymes in the liver that process clopidogrel, allowing it to work.

Dr Alex Doney, a consultant stroke physician at Ninewells Hospital in Dundee, said: “Genetic testing for stroke patients will save lives. For years, we've treated stroke patients on a one-size-fits-all basis, meaning people with completely different genetic make-ups receive exactly the same dose of the same drug. Yet we know that for many patients, the current drugs work no better than taking a placebo.”

Pharmacogenomics - the process of tailoring treatments to patients’ genetics - has the potential to improve outcomes in numerous areas of medicine. Tayside NHS Trust is among the first in the UK to offer the £22 blood test to stroke patients, which is completed when they arrive at hospital and blood clots have been identified as the cause of a stroke. The results are returned within a week and can then be used to personalise the treatment given.

Dr Doney added: “Genetic testing to ensure a particular treatment is safe and effective has actually been around for many years. Matching a patient’s blood group ahead of an operation is a very well established example of using genetic information to select the most appropriate treatment, which is something the public will be familiar with.”

Prior to the NHS rolling out this pioneering testing for stroke patients, the approach was trialled on a small number of patients who had already shared their genetic information for the purposes of health research. The new stroke test was developed by the East of Scotland Regional Genetic Laboratory based in Ninewells Hospital, which is leading the way in its delivery.

More than 100,000 strokes happen in the UK every year and knowing the signs - facial weakness, arm weakness and speech problems - make it clear when to call 999. Acting quickly is important to improve the chances of survival and recovery. Some 1.3 million people in the UK are stroke survivors and taking medication to prevent a repeat incident.