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NEUROLOGY 2008;71:1417-1423
© 2008 American Academy of Neurology

The HAT Score

A simple grading scale for predicting hemorrhage after thrombolysis

M. Lou, MD, PhD, A. Safdar, MD, M. Mehdiratta, MD, S. Kumar, MD, G. Schlaug, MD, L. Caplan, MD, D. Searls, MD and M. Selim, MD, PhD

From The 2nd Affiliated Hospital of Zhejiang University (M.L.), School of Medicine, Hangzhou, China; and Beth Israel Deaconess Medical Center (A.S., M.M., S.K., G.S., L.C., D.S., M.S.), Harvard Medical School, Boston, MA.

Address correspondence and reprint requests to Dr. Magdy Selim, Department of Neurology, Stroke Division, Beth Israel Deaconess Medical Center, 330 Brookline Avenue, Palmer 127, Boston, MA 02215 mselim{at}bidmc.harvard.edu

Objective: To develop a grading scale to predict the risk of intracerebral hemorrhage (ICH) and prognosis after treatment with IV tissue-plasminogen activator (t-PA) in patients with ischemic stroke.

Methods: We constructed a five-point scale based on NIH Stroke Scale score, extent of hypodensity on CT scan, serum glucose at baseline, and history of diabetes to predict the risk of hemorrhage after thrombolysis (HAT score). We evaluated the predictive ability of this scale, using c-statistics, in two independent cohorts: the t-PA treated group in the National Institute of Neurological Disorders and Stroke study, and consecutive patients treated with IV t-PA at our institution.

Results: The percentage of patients who developed any ICH after t-PA increased with higher scores in both cohorts. Collectively, the rate of any symptomatic ICH was 2% (0 point), 5% (1 point), 10% (2 points), 15% (3 points), and 44% (>3 points). The c-statistic was 0.72 (95% CI 0.65–0.79; p < 0.001) for all hemorrhages; 0.74 (0.63–0.84; p < 0.001) for symptomatic hemorrhages; and 0.79 (0.70–0.88; p < 0.001) for hemorrhages with final fatal outcome. Similar results were obtained when each cohort was analyzed separately. The score also reasonably predicted good (mRS ≤ 2) (c-statistic 0.75; 0.69–0.80; p < 0.001) and catastrophic (mRS ≥ 5) (0.78; 0.72–0.84; p < 0.001) functional outcomes on day 90 in the National Institute of Neurological Disorders and Stroke t-PA-treated patients.

Conclusions: The hemorrhage after thrombolysis (HAT) score is a practical, quick, and easy-to-perform scale that allows reasonable risk stratification of intracerebral hemorrhage after IV tissue-plasminogen activator (t-PA). However, the prognostic value of this scale and its use to predict the net benefit from t-PA needs to be refined and prospectively confirmed in a larger cohort of patients before it can be used in clinical decision-making.

Abbreviations: AIS = acute ischemic stroke; DWI = diffusion-weighted imaging; HAT score = hemorrhage after thrombolysis score; HFFO = hemorrhage with final fatal outcome; IA = intra-arterial; ICH = intracerebral hemorrhage; MCA = middle cerebral artery; mRS = modified Rankin Score; NIHSS = National Institutes of Health Stroke Scale; NINDS = National Institute of Neurological Disorders and Stroke; ROC = receiver-operator curves; SICH = symptomatic ICH; t-PA = tissue-plasminogen activator; TPI = Thrombolytic Predictive Instrument.

Dr. Lou is supported by Zhejiang University Academic Stars Research Fellowship and grants from the National Natural Science Foundation of China (30500175); Dr. Selim is supported in part by grants from NINDS (1R01-NS 057127-01A1 and 1R01-NS 045754-01A2) and NIH (5R01-HL46690-14).

Disclosure: The authors report no disclosures.

Received October 1, 2007. Accepted in final form June 6, 2008.






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