Image caption A stroke can cause permanent loss of function

Patients given a clot-busting drug within six hours of a stroke are more likely to have a good quality of life 18 months afterwards, an international study suggests.

However, the review of more than 3,000 patients found the drug - alteplase - offered no improvement in survival rates.

The drug is increasingly being used in specialist stroke units in the UK.

The Stroke Association said the Lancet Neurology research was "encouraging".

Quality of life

The treatment is given to patients who have had an ischaemic stroke, when the brain's blood supply is interrupted by a clot.

The sooner patients receive treatment the more likely they are to make a better recovery Dr Clare Walton,, Stroke Association

A stroke can cause permanent damage such as paralysis and speech problems, and can be fatal.

Without treatment, a third of people who suffer a stroke die, with another third left permanently dependent and disabled.

This international trial, led by researchers at the University of Edinburgh, followed patients from 12 different countries - half had the alteplase treatment, which is given intravenously, and half did not.

It was funded by the UK and Australian governments, the UK Stroke Association, the Medical Research Council and Health Foundation UK, with no funding from the pharmaceutical company that makes the drug.

The researchers suggest that for every 1,000 patients given the drug within six hours of stroke, by 18 months, 36 more will be able to manage independently and will have less pain and discomfort than if they had not had it.

However that is the average - and more of those given alteplase within the first hour or two after a stroke will see such benefits.

'Difficult decision'

The drug does carry a risk of causing a potentially fatal bleed in the brain in the first week after treatment for around three in 100 patients.

The experts behind the study say patients and their families have to weigh up the risks as well as the potential benefits.

It is personal choice, comparing immediate risk versus long-term benefits Prof Peter Sandercock,, University of Edinburgh

Prof Peter Sandercock, of the University of Edinburgh's Centre for Clinical Brain Sciences, who led the study, said: "What doctors need to do is to say this is a difficult decision for patients and their families. They have to say this is a treatment that carries risks."

He said someone who had experienced a major stroke which would affect their ability to live and work as they had previously may wish to take the drug, despite the bleed risk, whereas a patient who had a more minor stroke which did not affect them so badly may not.

"It is personal choice, comparing immediate risk versus long-term benefits."

Prof Sandercock added: "In the UK in 2002, the estimated annual cost of long-term care of an independent survivor of stroke and a dependent survivor were £876 and £11,292 respectively, so even a small difference in the proportion of survivors who are able to look after themselves will have a substantial economic impact."

Dr Clare Walton, of the Stroke Association, said: "There are over 150,000 strokes in the UK each year, and around 85% of these are caused by a blood clot in the brain.

"If these patients can get to hospital within four-and-a-half hours, some are eligible for clot-busting treatments which can greatly reduce brain damage and disability after stroke."

She said it was "encouraging" to see that the positive effects of treatment were maintained over the longer term.

Dr Walton added: "When a stroke strikes, time lost is brain lost. The sooner patients receive treatment the more likely they are to make a better recovery."