The risk of a major stroke occurring within a week after a minor stroke or transient ischaemic attack (TIA) is substantial, according to an Article to be published early Online and in the December issue of The Lancet Neurology. Furthermore, the lowest risk of stroke was reported among patients treated as emergency cases in specialist stroke units.
Although many studies have looked at the risk of stroke after a minor stroke or TIA, results have been conflicting, with 7-day stroke risk ranging from 0% to 12.8%. This has led to problems with their interpretation. However, reliable estimation of risk could maximise the benefits of early treatment, allow effective planning of service provision, inform future clinical trial design, and justify investment in public education.
Dr Matthew Giles and Professor Peter Rothwell (Stroke Prevention Research Unit, University of Oxford, UK) systematically reviewed studies of the risk of stroke within 7 days after a TIA to estimate overall stroke risk, and also look at the influence of study method, setting, population, treatment, and case mix.
The researchers combined results from 18 cohorts including 10126 patients, and showed that the risk of stroke after a TIA is substantial at 5.2% at 7 days (ie, one in twenty patients who have a TIA will go on to have a stroke within a week). According to the authors, although the individual results of the studies are inconsistent, this study shows that this can be almost fully explained by differences in study method, setting, and treatment. Further, they found that the lowest risks of stroke were seen in studies of emergency treatment in specialist stroke units (0-9%) and the highest in population-based studies without urgent treatment (11%).
The authors say: "Our study almost fully explains why the results of previous studies have been conflicting, and illustrates the importance of the methods used by a medical study when interpreting its results*."
They conclude: "The risk of stroke reported amongst patients treated urgently in specialist units was substantially lower than risks reported among other patients treated in alternative settings. These results support the argument that a TIA is a medical emergency and that urgent treatment in specialist units may reduce the risk of subsequent stroke. This is particularly relevant in the UK, where TIA services are patchy and there are substantial delays to TIA patients receiving appropriate treatments"
Notes to Editors
*Quotes are from the author directly and cannot be found in the text of the article.
The results are consistent with (and include) the EXPRESS Study (Lancet 2007; 370: 1432-42) and SOS-TIA study (Lancet Neurology 2007; 6: 953-60). The results are also consistent with (but do not include, for methodological reasons) the FASTER study (Lancet Neurology 2007; 6: 961-69). By taking these 4 studies together, our understanding of the prognosis and effective treatment of TIA is advanced.
The paper associated with this release can be found below:
http://www.eurekalert.org/jrnls/lance/TLNGilesfinal.pdf
Journal
The Lancet Neurology