Abstract 29: Initial NIHSS Predicts Poor Short-term Outcome After Minor Stroke Even at Very Low Scores

Abstract

Background: Minor ischemic stroke patients often do not receive IV tPA due to mild or rapidly resolving symptoms as it is assumed that they will have excellent outcomes without treatment. Nevertheless, a substantial proportion of these patients have a poor outcome. It is unclear if this is due to factors such as preexisting disability, medical comorbidities, or recurrent stroke, or due to the deficits associated with the minor stroke, We hypothesized that initial stroke severity would predict poor short-term outcome even when the deficits are mild. Methods: We conducted a retrospective cohort study based on chart review of all patients with minor ischemic stroke, as defined by NIHSS≤6 at presentation, who were admitted to our hospital over a 30-month time period. Poor short-term outcome was defined by in-hospital death or discharge to any destination other than home. Results: Data were complete for 461 of 471 patients with minor stroke. A substantial proportion, 38% (95%CI 34-43%), had a poor short-term outcome, including 31% discharged to rehabilitation, 5% discharged to a nursing facility, and 2% dead or discharged to hospice. Impaired ambulation prior to admission was associated with a poor outcome (OR 3.4; 95%CI 1.1-10, p<0.03), but only present in 3% of patients. In multivariable analysis, poor outcome was strongly associated with initial NIHSS ( figure ; OR 1.5; 95%CI 1.3-1.7, p<0.001) and age (OR 1.04; 95%CI 1.03-1.06, p<0.001). Similarly, NIHSS predicted poor outcome when analysis was limited to initial NIHSS≤3 (OR 1.8; 95%CI 1.3-2.4, p<0.001). Of the 112 patients presenting within 4.5 hours of time last seen well, 15% received IV tPA and 45% were excluded solely due to mild or rapidly improving symptoms. NIHSS was lower in those patients excluded than in those who received tPA (median 2 vs. 5, p<0.001). After adjustment for age, NIHSS, and prior ambulatory status, there was no significant difference in poor outcome, which occurred in 42% of patients treated with tPA and 24% of those excluded due to mild or rapidly improving symptoms (OR 1.9 for poor outcome after tPA; 95%CI 0.4-9.5, p=0.43). Conclusions: More than one-third of patients with minor stroke had a poor short-term outcome, including nearly one-fourth of those who were excluded from IV tPA due to mild or rapidly improving symptoms. NIHSS was predictive of poor outcome at very low scores, consistent with the hypothesis that the deficits due to the initial stroke were responsible for poor outcome. However, the impact of tPA treatment in this population is uncertain.