TIA Linked To Substantial Risk for Major Stroke Within a Week

November 19, 2007 — New research suggests patients who experience a transient ischemic attack (TIA) are at substantial increased risk of having a major stroke within 1 week, a finding that researchers say warrants treating TIA as a medical emergency.
Led by Matthew F. Giles, MD, DPhil, and Peter M. Rothwell, MD, PhD, FRCP, of the University of Oxford, United Kingdom, this large systematic review showed that the risk for major stroke after a TIA is 5.2% at 7 days and 3.2% at 2 days.
"We found the risk of stroke after TIA is high — about 5% within a week — which works out to about one in 20 patients," Dr. Giles told Medscape Neurology & Neurosurgery.
The study is published in the November 12 Online First issue of The Lancet Neurology.
First Meta-Analysis of Early Stroke Risk
According to Dr. Giles, this is the first meta-analysis to examine stroke risk in the early period after TIA. Results from previous individual studies that have looked at this issue have reported inconsistent results.
To gain a reliable estimation of early stroke risk, the investigators identified all studies examining stroke risk within 7 days of a TIA. This amounted to a total of 18 cohort studies, all of which had been published since 2000, and included 10,126 patients who had a TIA.
Of note, said Dr. Giles, is the fact that the lowest risk for subsequent stroke was seen in studies in which subjects received emergency treatment in a specialist stroke service, whereas the highest risk was seen in population-based studies in which individuals did not receive urgent treatment.
Furthermore, the researchers said the variation in individual study results are almost fully explained by differences in study method, setting, and treatment.
"Our study showed that these diverse findings (among individual studies) can be explained almost entirely by differences in methodology. The reason for the conflicting study results has to do with the way in which a study is conducted and the way in which risk is measured. If you measure risk using different methods, settings, populations, and treatments, the results will be different," he said.
Management of TIA "Patchy"
Although this study finding is of interest from an academic research perspective, Dr. Giles added, it also has major implications in informing TIA management.
The study follows on the heels of 2 other major research articles showing that rapid assessment and treatment of a first TIA or minor ischemic stroke dramatically reduces the risk for subsequent major stroke.
The Early Use of Existing Preventive Strategies for Stroke study from Dr. Giles and his group at Oxford University and the SOS-TIA study from researchers at Bichat-Claude Bernard University Hospital and Denis Diderot University and Medical School in Paris, France, were published in The Lancet and The Lancet Neurology, respectively, in October 2007.
However, despite this growing evidence that early, aggressive management of TIA significantly reduces major stroke risk, national audits reveal that management of TIA in the United Kingdom is "patchy" and ranges from full-immediate emergency inpatient treatment and monitoring for up to 7 days to significant delays in initial assessment of 2 days or more.
Need for Speed
"I suspect the vast majority of patients with TIA are ultimately seen at a stroke service. But the point is if people aren't seen quickly then the service isn't going to be effective in preventing subsequent stroke risk," said Dr. Giles.
He added that this study, as well as the 2 recent articles published in The Lancet, provides a strong impetus for healthcare reform and public education efforts geared towards immediate and effective management of TIAs.
"Based on this, as well as the previous research, I suspect there will be a national movement to improve the provision of service (for TIA patients). Whether that is in an inpatient or outpatient setting probably doesn't matter. The point is that patients need to be assessed and treated quickly," he said.
Asked by Medscape Neurology & Neurosurgery to comment on the study Philip Gorelick, MD, from the University of Illinois College of Medicine at Chicago, said Giles and Rothwell's analysis highlights the importance of immediate medical attention for symptoms of TIA.
Neurologists, he said, have long been aware that TIA constitutes medical emergency. However, it is important that the resources and infrastructure to manage it as such are available.
"Early treatment for TIA may be highly beneficial in terms of reducing stroke risk and its devastating complications. On the other hand, a delay [in diagnosis and treatment] may lead to neurological disaster," said Dr. Gorelick.
Dr. Giles has received funding by the Stroke Association. Dr. Rothwell has disclosed no relevant financial relationships.
Lancet Neurol. Published online November 12, 2007.