Association between Prehospital Delay Status and Stroke Severity in Acute Ischemic Stroke: Shift-Analysis Approach

Objective: We investigated the association between stroke severity and pre-hospital delay of patients with an acute ischemic stroke (AIS).Method: A consecutive 1,412 patients with AIS enrolled in the acute stroke registry were included in the final study. Stroke severity was assessed by National Institute of Health Stroke Scale (NIHSS) score. A pre-hospital delay between less than 3 h and 3 h or more was compared using Pearson's chi-square for categorical variables and Student's t-test or Mann-Whitney U test for continuous variables, as appropriate. Association between initial NIHSS score and pre-hospital delay was plotted with Spearman’s correlation analysis. We used the analysis of variance or Kruskal-Wallis test and chi-squared test to compare the baseline characteristics according to NIHSS tertile. We analysed the variables associated with the higher shift of NIHSS tertile using an ordinal logistic regression analysis.Results: Increased stroke severity decreased the pre-hospital delay (Spearman’s rho=-0.216, p<0.001). Age (common odds ratio (cOR), 1.03; 95% confidence interval (CI), 1.02-1.03; p<0.001), history of previous stroke (cOR, 1.56; 95% CI, 1.25-1.94; p<0.001) and pre-hospital delay ≥ 3 h (cOR, 0.48; 95% CI, 0.39-0.59; p<0.001) were associated with higher shift of NIHSS tertiles in univariable ordinal logistic regression analyses. In multivariable model, pre-hospital delay ≥ 3 h is a negative predictor for higher shift of NIHSS tertile (cOR, 0.49; 95% CI, 0.39-0.61; p<0.001).Conclusion: As the stroke severity increased, onset-to-hospital arrival time was decreased in AIS patients. Therefore, the findings suggest the need for development of individualized educational programs for each stroke patient.