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 neu rological changes during the first 48 hours after acute stroke as it relate s to initial stroke severity, Methods The National Institutes of Health Stroke Scale (NIHSS) was performe d serially for the first 48 hours on 127 consecutive ischemic stroke patien ts (129 strokes) admitted to the neuroscience intensive care unit. Incidenc e of stroke progression (a greater than or equal to 3-point increase on the NIHSS) was recorded and analysis performed to determine its association wi th initial stroke severity and other demographic and physiological variable s, Deficit resolution by 48 hours, defined as an NIHSS score of 0 or 1, mea sured the frequency of functional recovery predicted by the initial deficit , Results-Overall progression was noted in 31% of events (40/129). Applying B ayes' solution to the observed frequency of worsening, the greatest likelih ood of predicting future patient progression occurs with stratification at NIHSS scores of less than or equal to 7 and >7. Patients with an initial NI HSS of less than or equal to 7 experienced a 14.8% (13/88) worsening rate v ersus a those with a score of >7 with a 65.9% (27/41) worsening rate (P<0.0 00005). Forty-five percent (40/88) of those with an initial score of less t han or equal to 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 th is period (chi(2), P<0.000005). Conclusions-This study suggests that the early clinical course of the neuro logical deficit after acute stroke is dependent on the initial stroke sever ity and that a dichotomy in early outcome exists surrounding an initial NIH SS score of 7. These findings may have significant implications for the des ign and patient stratification in treatment protocols with respect to prima ry clinical outcome.