Published online before print May 14, 2007, doi: 10.1161/CIRCULATIONAHA.106.651026
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(Circulation. 2007;115:2660-2665.)
© 2007 American Heart Association, Inc.
Stroke |
Accuracy of Serial National Institutes of Health Stroke Scale Scores to Identify Artery Status in Acute Ischemic Stroke
From the Department of Neurology, University of Texas Health Science Center at Houston (R.M., J.C.G., M.M., A.V.A.), Houston, Tex; Cerebrovascular Unit, Vall d’Hebron Hospital (M.R., C.M., J.A.-S., M.R., R.D.-M.), Barcelona, Spain; and Department of Clinical Neurosciences and the Departments of Community Health Science and Medicine, University of Calgary (M.D.H.), Calgary, Canada. Dr Mikulik is currently with the Department of Neurology, Masaryk University, St Anne Hospital, Brno, Czech Republic. Drs Malkoff and Alexandrov are currently with the Barrow Neurological Institute, Phoenix, Ariz.
Correspondence to Robert Mikulik, Neurologicka klinika, FN u sv.Anny, Pekarska 53, 656 91, Brno, Czech Republic. E-mail mikulik{at}hotmail.com
Received July 11, 2006; accepted February 22, 2007.
Background— Early recovery after intravenous thrombolysis can be observed in stroke; however, the utility of measuring clinical improvement to assess artery status has not been established. We sought to determine the accuracy of serial National Institutes of Health Stroke Scale (NIHSS) scores to detect complete early recanalization of the middle cerebral artery.
Methods and Results— Data from the CLOTBUST trial (Combined Lysis of Thrombus in Brain Ischemia Using Transcranial Ultrasound and Systemic tPA) were used to determine the most sensitive and specific NIHSS-derived parameter to identify complete recanalization. Then, reproducibility was tested against a separate patient population (Barcelona data set). NIHSS scores were determined before tissue plasminogen activator bolus and at 60 and 120 minutes in both data sets. Receiver operating characteristic curves were used to compare test performance. The accuracy of individual cutoffs was demonstrated by sensitivity, specificity, and positive and negative predictive values. A total of 122 patients in the CLOTBUST data set and 98 in the Barcelona data set received 0.9 mg/kg intravenous tissue plasminogen activator [mean age 69±12 versus 72±12 years, 57% male versus 51% male, median NIHSS 16 versus 17 points, mean time from onset to treatment 140±32 versus 177±59 minutes, and complete recanalization of the middle cerebral artery in 19% versus 17%). For identification of recanalization, an NIHSS score reduction of 
40% offered the best tradeoff, with sensitivity, specificity, positive predictive value, and negative predictive value of 65%, 85%, 50%, and 91% at 60 minutes and 74%, 80%, 58%, and 89% at 120 minutes, respectively. Test performance was equal in the Barcelona data set.
Conclusions— Relative changes in serial NIHSS scores can serve as a simple clinical indicator of arterial status after intravenous thrombolysis. Accuracy parameters are affected by the process of recanalization and its varying clinical significance.
CLINICAL PERSPECTIVE
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