Chandratheva, A. et al. Population-based study of risk and predictors of stroke in the first few hours after a TIA. Neurology 72, 1941–1947 (2009).

A prospective study of the risk of stroke in patients who have experienced a transient ischemic attack (TIA) reveals that 5% of patients have a serious stroke within 24 h of their TIA, providing justification for regarding TIA as a full medical emergency. “We also showed that the commonly used ABCD2 risk score worked well in this hyperacute' phase and could identify higher-risk individuals quite accurately,” comments senior author Peter Rothwell, of the Department of Clinical Neurology, Oxford University, UK, whose research forms part of the Oxford Vascular Study.

Arvind Chandratheva and colleagues performed a prospective, population-based incidence study with complete follow-up of 1,247 patients with TIA and stroke. “We chose to adopt this methodology because it was the only way to determine the risk of stroke prospectively in patients with TIA. This is much more reliable than trying to work out risk retrospectively from routinely collected data or medical records,” points out Rothwell. Accurate risk assessments are essential to guide clinicians in the best management of the many thousands of individuals per year who experience TIAs. “Much of the work leading up to this study showed that the risk of major stroke after a TIA was much higher than previously thought. Guidelines have changed recently, but only to say that high-risk patients should be assessed within 24 h,” Rothwell explains.

Chandratheva et al. showed that in 488 patients who experienced a TIA, the stroke risk at 6 h, 12 h and 24 h was 1.2%, 2.1% and 5.1%, respectively. “We think that the 5% risk of major stroke within 24 h of a TIA would seem to justify emergency status,” notes Rothwell. Moreover, the risk of stroke at the 12-hour and 24-hour time points was strongly associated with the ABCD2 score, which was originally developed to predict the risk of recurrent stroke within 7 days of a TIA. This study is the first to show that this score can also predict stroke risk within the first few hours after a TIA. “We also found that 64% of TIA cases that experienced a subsequent full-blown stroke did seek urgent medical attention, but none received timely treatment with antiplatelet agents,” Rothwell adds.

Rothwell stresses that the group's previous research has demonstrated that urgent treatment can substantially reduce the risk of stroke soon after a TIA. “Many of these very early strokes are, therefore, also preventable,” he says. If the ABCD2 score is high, Rothwell recommends that patients are treated “immediately”. He also draws attention to the 36% of patients with TIA who were not taken straight to hospital. “We also need public education to get patients to present earlier—many patients still ignore the symptoms of a TIA and delay possibly life-saving treatment,” he concludes.