The Recurrence Risk Estimator (RRE) for ischaemic stroke has been validated in a prospective, multinational study.
Although the tool's sensitivity was low, specificity was high, at 90% for identifying high-risk patients and 93% for low-risk patients.
In an accompanying editorial, Graeme Hankey (The University of Western Australia, Perth) and Chee-Keong Wee (National Neuroscience Institute, Singapore) suggest that "[t]he greatest value of the RRE could perhaps be its ability to accurately identify the one-third of patients with ischemic stroke who are at low risk of a recurrence."
The RRE categorised 540 of the 1468 patients as low-risk (RRE score of 0) and the cumulative 90-day recurrence rate among these patients was 0.8%. By contrast, there were 170 patients in the high-risk category, among whom the recurrence rate was 11.9% for those with an RRE score of 3 and 25.0% for those with a score of 4 or more.
However, 3.5% of patients with a score of 1 had a recurrent stroke, as did 5.4% of those with a score of 2; although the recurrence rates were low, this low-to-medium risk subgroup was the largest and therefore accounted for the greatest proportion of strokes in the cohort. This may limit the usefulness of the RRE in clinical practice, say Hankey and Wee.
The study cohort consisted of 814 patients from the USA and 654 recruited in centres in South Korea and Brazil. The RRE had similar predictive ability in the US and Korean/Brazilian cohorts, Hakan Ay (Massachusetts General Hospital, Boston, USA) and study co-authors report in JAMA Neurology.
The total possible score for the RRE is 6, with 2 points available for clinical predictors (stroke within previous month and large-artery atherosclerosis or uncommon aetiology) and another 4 points for the number, age and distribution of infarcts on magnetic resonance imaging (MRI).
This is another possible limitation, say the editorialists - that the RRE requires rapid access to brain MRI.
However, they say that the tool "is simple to use" and is "plausible as a prognostic instrument because the variables reflect the cause of the stroke and its activity and instability."
They add: "Further research that tests the value of adding newly identified potential predictors (eg, blood or other imaging markers of underlying cardiovascular disease activity) promises to further improve the predictive ability of the RRE and other prognostic models."
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