The stroke-thrombolytic predictive instrument provides valid quantitative estimates of outcome probabilities and aids clinical decision-making.

See related article, pages 2957–2962 Computerized clinical decision support systems are increasingly popular in health sciences and have been demonstrated to improve practitioner performance.1 For an emergency closely related to ischemic stroke, acute myocardial infarction, a thrombolytic predictive instrument was developed for real-time use in emergency medical-service settings to identify patients likely to benefit from thrombolysis and to facilitate the earliest possible use of this therapy.2,3 A similar instrument, designed for ischemic stroke, could also prove to be useful. Thrombolysis for ischemic stroke remains underused even under ideal circumstances. Approximately 40% of emergency physicians in a national survey report that they would not use recombinant tissue plasminogen activator (rt-PA) for stroke, citing the risk of symptomatic intracranial hemorrhage and relative lack of benefit.4 Similar results were reported by Bobrow et al in a survey of the Arizona chapter of the American College of Emergency Physicians. Only 52% of the emergency physicians who responded to the survey indicated that they would endorse rt-PA use for stroke under ideal conditions.5 Physicians’ perceptions of risks and benefits of rt-PA for stroke are not uniformly accurate.6 Merino et al reported that only 11% (95% CI, 0 to 22) of surveyed emergency medicine physicians and neurologists could correctly convey the expected magnitude of beneficial effect of rt-PA, and that only 39% (95% CI, 21 to 57) could accurately report the expected rate of symptomatic and fatal intracranial hemorrhage of rt-PA.6 This misperception may interfere with their willingness to endorse this treatment. It would be helpful to draw a distinction between true and perceived efficacy and between true and perceived harm associated with rt-PA for stroke. In this issue of Stroke, Kent et al7 developed a Stroke-Thrombolytic Predictive Instrument (TPI) to aid physicians considering thrombolysis for a patient with acute ischemic stroke. The authors used data from 5 major randomized clinical trials testing rt-PA in acute ischemic stroke. They developed logistic regression equations using clinical variables as potential predictors of a good outcome (defined as modified Rankin Scale score 1) and potential predictors of a catastrophic outcome (defined as modified Rankin Scale score 5) with and without use of rt-PA. To predict good outcome, the rt-PA treatment, age, diabetes, stroke severity, gender, prior stroke, systolic blood pressure, and time from symptom onset significantly affected prognosis. To predict catastrophic outcome, only age, stroke severity, and serum glucose significantly affected prognosis; rt-PA did not. The Stroke-TPI that was created is capable of predicting good and bad functional outcomes for acute ischemic stroke patients with and without thrombolysis. Consider the following 2 acute ischemic stroke scenarios: In the first scenario, a 77-year-old woman with a history of diabetes mellitus presented to the emergency department relatively late in the course of her stroke symptoms. Her systolic blood pressure was 140 mm Hg, her serum glucose was 15.2 mmol/L, and her National Institute of Health Stroke Scale (NIHSS) score was low, only 5. By the time she had her intravenous lines placed, blood tests drawn and processed, and computed tomography of brain conducted and interpreted, the 3-hour window was nearly closed, at 179 minutes. The treating physician, patient, and accompanying family members had a critical decision to make and essentially no time in which to make it. The physician drew on traditionally available resources and clinical experience. In the National Institute of Neurological Disorders and Stroke (NINDS) rt-PA Stroke Study, on average, an acute ischemic stroke patient treated with rt-PA might expect an absolute risk reduction ranging from 11% to 15%, depending on the functional outcome scale.8 The physician attempted to balance that estimated treatment effect with the potential risk of harm from a symptomatic intracranial hemorrhage, quoted as 6.4%. The physician acknowledged that the later the treatment is administered, the lower the likelihood of a favorable outcome.9 A summary of postmarketing reports of rt-PA use in ischemic stroke has demonstrated that failure to adhere to indications and contraindications outlined in the guidelines, including time window, is associated with an increased risk of hemorrhagic complications.10 Finally, the treating physician’s common experience has been that there is invariably a good spontaneous recovery associated with a mild stroke, NIHSS score of 5, regardless of treatment.10 Ultimately, a decision was made to withhold rt-PA as the perceived risk outweighed the perceived benefit. In the second scenario, a young woman age 51 presented to the emergency department with a severe ischemic stroke, NIHSS score of 29. Her systolic blood pressure was 165 mm Hg, serum glucose was 13.1 mmol/L, and after all her examinations, diagnostic tests, and brain imaging were performed, 2 hours had already elapsed since symptom onset. Once again, a critical treatment decision had to be made. The prevailing thought that ran through the mind of the treating physician was that the woman’s prognosis was invariably extremely The opinions in this editorial are not necessarily those of the editors or of the American Heart Association. From the Mayo Clinic College of Medicine, Cerebrovascular Diseases Center, Department of Neurology, Mayo Clinic Arizona, Scottsdale, AZ. Correspondence to Bart M. Demaerschalk, MD, MSc, FRCP(C), Assistant Professor of Neurology, Mayo Clinic College of Medicine, Director, Cerebrovascular Diseases Center, Department of Neurology, Mayo Clinic Arizona, 13400 East Shea Blvd, Scottsdale, AZ 85259. E-mail [email protected] (Stroke. 2006;37:2865-2866.) © 2006 American Heart Association, Inc.