Letter by Rangaraju and Jadhav Regarding Article, “Predicting Clinical Outcomes After Thrombolysis Using the iScore: Results From the Virtual International Stroke Trials Archive”
To the Editor:
We commend Saposnik et al1 for their analysis of the effectiveness of thrombolytic therapy in acute ischemic stroke using iScore as a predictor of outcome in the Virtual International Stroke Trials Archive (VISTA) database. They clearly demonstrate that intravenous tissue-type plasminogen activator (tPA) increases the likelihood of achieving a good outcome (modified Rankin Scale [mRS], 0–2) at 3 months if the iScore is <200. This beneficial effect of tPA was not observed in the high iScore group (≥200). However, they did observe a significant difference in rates of catastrophic outcomes (mRS, 4–6) in the non–tPA-treated group as compared with the tPA group in the iScore≥200 group (odds ratio, 0.54). This result was explained by a ceiling effect because of high rates of poor outcomes in this subgroup of patients. They also found that hemorrhage rates were significantly higher in high iScore patients when treated with intravenous tPA.
In patients with iScore≥200 who tend to have higher stroke morbidity, mRS 0 to 3 (acceptable outcome) may be more clinically relevant than mRS 0 to 2, the standard measure of good clinical outcome in ischemic stroke trials. Acceptable outcome has also been used as a clinical outcome measure in intracerebral hemorrhage trials.2 In our interpretation of the data presented by Saposnik et al,1 we found that the rate of acceptable outcomes in the iScore≥200 cohort was 24.8% (65/262) in tPA-treated patients compared with 13.8% (54/392) in untreated patients (odds ratio for acceptable outcome, 2.1; 95% confidence interval, 1.4–3.1; P=0.0004). In addition, 3-month mortality rate was significantly lower in the tPA-treated group (38.2%; 100/262) compared with untreated patients (48.5%; 190/392) with an odds ratio of 0.66 (95% confidence interval, 0.47–0.90).
Although recognizing that our analysis is unadjusted for other variables, we suggest that in patients with iScore≥200 who have higher stroke severity, advanced age, greater comorbidities, or poor baseline mRS, intravenous tPA may improve the likelihood of achieving an acceptable clinical outcome with decreased mortality rates. This observation may be used to guide patients and families during decision making with regards to intravenous thrombolysis in acute stroke.
Srikant Rangaraju, MD
Ashutosh P. Jadhav, MD, PhD
Department of Neurology
University of Pittsburgh Medical Center
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- © 2013 American Heart Association, Inc.