Progression in acute stroke: value of the initial NIH stroke scale score on patient stratification in future trials.

BACKGROUND AND
PURPOSE: The objective was to determine the occurrence of neurological changes during the first 48 hours after acute stroke as it relates to initial stroke severity.
METHODS: The National Institutes of Health Stroke Scale (NIHSS) was performed serially for the first 48 hours on 127 consecutive ischemic stroke patients (129 strokes) admitted to the neuroscience intensive care unit. Incidence of stroke progression (a >/=3-point increase on the NIHSS) was recorded and analysis performed to determine its association with initial stroke severity and other demographic and physiological variables. Deficit resolution by 48 hours, defined as an NIHSS score of 0 or 1, measured the frequency of functional recovery predicted by the initial deficit.
RESULTS: Overall progression was noted in 31% of events (40/129). Applying Bayes' solution to the observed frequency of worsening, the greatest likelihood of predicting future patient progression occurs with stratification at NIHSS scores of </=7 and >7. Patients with an initial NIHSS of </=7 experienced a 14.8% (13/88) worsening rate versus a those with a score of >7 with a 65.9% (27/41) worsening rate (P<0.000005). Forty-five percent (40/88) of those with an initial score of </=7 were functionally normal at 48 hours, whereas only 2.4% (1/41) of those with scores of >7 returned to a normal examination within this period (chi2, P<0.000005).
CONCLUSIONS: This study suggests that the early clinical course of the neurological deficit after acute stroke is dependent on the initial stroke severity and that a dichotomy in early outcome exists surrounding an initial NIHSS score of 7. These findings may have significant implications for the design and patient stratification in treatment protocols with respect to primary clinical outcome.