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Higher-risk patients according to a simple risk score incorporating age and stroke severity appear to derive the most benefit from thrombolytic therapy for an acute ischemic stroke, an observational study showed.
Although patients with a SPAN-100 score indicating high risk had an greater overall risk of adverse outcomes compared with lower-risk patients, they had a significant reduction in the likelihood of death or severe disability at 3 months when they received intravenous thrombolytics (adjusted odds ratio 0.46, 95% CI 0.29-0.71), according to Bruce Ovbiagele, MD, of the Medical University of South Carolina in Charleston, and colleagues.
Thrombolytic therapy was not associated with the likelihood of that outcome in the lower-risk patients (aOR 0.96, 95% CI 0.85-1.07), the researchers reported online in JAMA Neurology.
They acknowledged some limitations of the study, including the lack of randomized comparisons and the possibly overly simplistic risk score, but said, "at the very least, our data indicate that even though SPAN-100-positive patients have often been excluded from acute ischemic stroke clinical trials, they should probably not be denied on these grounds."
The SPAN-100 index adds together a patient's age in years and NIH Stroke Scale (NIHSS) score, which can range from 0 to 42 (with higher scores indicating more severe deficits). The SPAN-100 index is considered positive when the sum of those two numbers is 100 or greater.
A previous study showed that the index significantly predicted risk of intracerebral hemorrhage and various clinical outcomes in patients with an acute ischemic stroke, but Ovbiagele and colleagues wanted to see how the response to thrombolysis differed based on SPAN-100 status.
The analysis included information from the Virtual International Stroke Trials Archive (VISTA) database on 7,093 patients with acute ischemic stroke who participated in four clinical trials from 2000 to 2006 (the names of the trials were not available).
Overall, 10.5% of the patients had a SPAN-100 index of 100 or greater, and 38.5% received IV thrombolysis.
Compared with those with a low SPAN-100 index, those with a positive SPAN-100 index were more likely to have died or developed severe disability -- defined by a score of 4 to 6 on the modified Rankin Scale (mRS) -- 90 days after the stroke (aOR 9.03, 95% CI 6.68-12.21). They were also more likely to have died (aOR 5.03, 95% CI 4.06-6.23) and less likely to have achieved a favorable outcome defined by an mRS score of 0 to 2 (aOR 0.08, 95% CI 0.06-0.13).
But the use of thrombolysis was associated with an attenuation of those relationships and was associated with improved outcomes only among those with a high SPAN-100 index.
"As such, based on these observational data, the answer to the question posed about what to do regarding very elderly patients with very severe strokes (who are often excluded from acute stroke clinical trials) seems to be to treat them with intravenous thrombolysis (rather than skipping this treatment to pursue just comfort care) if they are SPAN-100 positive," the authors wrote.
Although age and stroke severity have been included in several previous risk scores, the SPAN-100 index has some particular merits, they wrote: "(1) the synergistic effect of its two components on prognosis, (2) its consistent relationship to several types of outcomes, (3) the potential for easy incorporation into risk adjustment for outcome-based measurements of hospital and provider performance, (4) use in eligibility criteria for future acute ischemic stroke trials, and (5) its ready applicability when counseling patients and families in virtually all clinical settings (especially the time-pressured setting of an acute ischemic stroke) by several provider types (emergency physicians, internists, and non-stroke neurologists).
"To the last point," they added, "although more detailed stroke scores include several additional variables that can add to their predictive power, this is likely at the expense of becoming much less practical and, therefore, being less often used."
From the American Heart Association:
Ovbiagele is supported by an award from the National Institute of Neurological Disorders and Stroke. One of his co-authors is supported by the Clinician-Scientist Award from the Heart and Stroke Foundation of Canada and the Canadian Institutes of Health Research.
- Reviewed by Zalman S. Agus, MD Emeritus Professor, Perelman School of Medicine at the University of Pennsylvania