Wednesday October 10 2007
Rapid treatment of a TIA reduces risk of a major stroke
Rapid treatment following a mini stroke (a transient ischaemic attack, or TIA) reduces the risk of a major stroke occurring by 80%, newspapers reported. The Daily Mail said that there is a 10% risk of “a major disabling or fatal stroke occurring in the first month” following a TIA, but that this could be reduced by prompt drug treatment, preventing up to 10,000 strokes from occurring annually.
The Independent said that the treatment was cheap and simple and “often a daily dose of aspirin will be enough”, but that the speed as which it is administered is key to its success.
The stories were based on a study of stroke and TIA incidence in the Oxford area. It is a fact recognised by medical professionals, that diagnosis and treatment following TIAs and strokes should be carried out as early as possible to prevent further events from occurring. This large and reliable study adds some measure of the extent of this benefit.
Where did the story come from?
Professor P.M. Rothwell and colleagues of the Stroke Prevention Research Unit, Radcliffe Infirmary, Oxford, carried out this research. The Oxford Vascular Study was funded by UK Medical Research Council, Dunhill Medical Trust, Stroke Association, Bupa Foundation, National Institute for Health Research, and Thames Valley Primary Care Research Partnership. The study was published in the peer-reviewed medical journal The Lancet.
What kind of scientific study was this?
This was a prospective before and after study in which the researchers observed how the introduction of a programme which gave rapid referral and treatment affected stroke outcomes for patients who had had a transient ischaemic attack (TIA).
The study, (called the Early Use of EXisting PREventative Strategies for Stroke [EXPRESS] study) was conducted in two phases. The first phase of the study began in 2002, with the opening of a new outpatient stroke clinic. Patients with TIA who were not admitted directly to hospital could be referred for an appointment at the new clinic, which assessed the patients and recommended treatment by the patient’s GP.
In the second phase of the study, which began in 2004, changes were made so that a clinic appointment was not necessary and patients could be seen on the same day. If a diagnosis of TIA was confirmed, treatment was started immediately. This included a platelet-lowering drug such as aspirin, and cholesterol, blood pressure or anticoagulant medications as required. A brain scan was also carried out in patients who still had symptoms.
Data were collected on when the patient presented for medical attention and when treatment was commenced, and a record made of the diagnosis of stroke or TIA according to the National Institutes of Health Stroke Scale.
The patients were monitored to see if they experienced a major stroke within 90 days of their assessment at the clinic. This was done through a daily search for all stroke events in the Oxford region using hospital and General Practice coding data, and via interviews with all patients at one, six, 12 and 24 months following the incident.
What were the results of the study?
A total of 1,278 strokes and TIAs presented during the course of the study. Of these, 310 presented to the EXPRESS clinic in phase 1 of the study (156 of whom had TIA), and 281 presented to the clinic in phase 2 (172 of whom had TIA). The rest of the cases were managed through hospital referral, other outpatient clinics, or only received general practice care.
During phase one of the study, patients had to wait significantly longer to be seen in the clinic than they did in phase two (an average three days wait in phase I compared to being seen within the first day in phase two).
Patients in phase one also had a longer interval between presentation at the clinic and their first prescription of recommended medication than those in phase two (20 days compared to one day).
At one month follow-up, patients in phase one were less likely to be taking one of the other recommended medications in addition to aspirin (e.g. a cholesterol or blood pressure lowering drug).
The risk of stroke in the 90 days following clinic presentation with TIA was significantly greater in phase one of the study (9.7% developed stroke) compared to phase two (0.6% developed stroke)
What interpretations did the researchers draw from these results?
The authors conclude that “urgent treatment and early initiation of a combination of existing preventative treatments can reduce the risk of early recurrent stroke after TIA by about 80%”.
They say that the number of all recurrent strokes in the whole population would be reduced by a half, and that if they extrapolate their findings across the UK, about 10,000 strokes per year could be prevented. They say that their results “have immediate implications for service provision and public education about TIA and minor stroke”.
What does the NHS Knowledge Service make of this study?
The medical profession already recognises that treatment following TIAs and strokes should be commenced as early as possible to prevent further events from occurring. This large and reliable study adds some measure to the amount of benefit that rapid treatment has.
There are a few points to consider:
- Because existing evidence suggested that early treatment would be beneficial, researchers felt that it would have been unethical to randomise patients into whether they received early treatment or not, which is why the results had to be observed following a change in clinical practise. As the patients were not randomised into groups, and were seen at different times, there could be some imbalance between the groups, such as their other risk factors for stroke, or whether they were taking previous treatment. The researchers did compare the people in phases one and two, and found that they were similar in most characteristics, although there were more people taking cholesterol lowering drugs in phase two. This and other factors may still have some slight affect on results. However, the large improvements seen, suggest that they are likely to be because of the change in practice.
- The authors were not able to completely quantify the effects of each of the medications that were given in the study, i.e. those that were contributing to a reduction in risk, and these effects would have been slightly different between patients. However, it is known that early administration of aspirin is probably the most important factor.
This study suggests that the current protocol in general practice for the referral and commencement of treatment following TIAs and strokes, may need to be examined more closely to ensure that best practice for stroke prevention is followed.
Sir Muir Gray adds...
This is probably the research report of 2007. We have to get what we know into practice as soon as possible.