What change in the National Institutes of Health Stroke Scale should define neurologic deterioration in acute ischemic stroke?

BACKGROUND: Neurologic deterioration (ND) occurs in one-third of patients with stroke. However, the true incidence of ND and risk for adverse outcomes remains unknown because no standardized definition of ND exists. Our study compared the prognostic value of a range of definitions for ND in patients with acute ischemic stroke (AIS).
METHODS: All patients who presented to our center with AIS within 48 hours of symptom onset between July 2008 and June 2010 were retrospectively identified. Patient demographics, National Institutes of Health Stroke Scale (NIHSS) scores, etiologies of ND, and outcome measures were compared between patients according to a range of ND definitions using receiver operating characteristic analyses.
RESULTS: Three hundred forty-seven patients were included. The 2 definitions of ND with the highest sensitivity and specificity for several outcome measures were tested against each other: an increase in the NIHSS score by ≥2 or ≥4 points in a 24-hour period. More than one third (36.9%) of patients experienced ≥2-point ND versus 17.3% with ≥4-point ND. Patients who experienced ND by either definition had prolonged hospitalization (P < .001), poorer functional outcome (discharge modified Rankin Scale score >2; P < .001), and higher discharge NIHSS score (P < .001) compared to patients without ND. Compared to patients without ND, a ≥2-point ND was associated with a 3-fold risk of death (odds ratio 3.120; 95% confidence interval 1.231-7.905; P < .0165) after adjusting for admission NIHSS score, serum glucose, and age.
CONCLUSIONS: A ≥2-point ND is a sensitive indicator of poor outcome and in-hospital mortality. An accepted definition of ND is needed to systematically study and compare results across trials for ND in patients with stroke.