Geographic Distribution of Acute Ischemic Stroke admissions in the United States
Background:
The geographic distribution of acute ischemic stroke in the United States has not been evaluated, unlike the association shown with acute MI by Patel et al., (International Journal of Cardiology, 2014, 172.3). Our study looked at the geographic distribution and seasonal variation of acute ischemic stroke using the National Inpatient Sample (NIS) from 2011 - 2013.
Methods:
Adult admissions with a primary diagnosis of acute ischemic stroke were extracted from the NIS database using the ICD 9 code 434.91 from 2011 - 2013. Admission information included hospital region (West, South, Mid-Atlantic and Northwest) and seasonal admission rates (Winter=December-February, Spring=March-May, Summer=June-August, Fall=September-November). A Chi square analysis was used to analyze differences in categorical variables (we assumed a normal distribution of 25% per region).
Results:
A total of 120714 admissions were identified (weighted = 603361). There were more cases of acute ischemic stroke in the South (41.52 percent of admissions) compared to the mid Atlantic (21.4), Northwest (17.98) or West (19.08) with a p value < 0.0001. Each year between 2011 to 2013 showed a higher rate of admissions for acute ischemic stroke in the South. Taking the years into summation showed no statistically significant difference in seasonal variation in any of the regions.
Conclusion:
Our study shows a higher number of admissions for acute ischemic stroke in the South, but failed to show any seasonal differences. However, there are several studies that suggest a preponderance of admissions for acute myocardial infarction during the winter season, Spencer et al., (Journal of the American College of Cardiology, 1998, 31.2.) Further studies are needed to identify why there is a significant regional difference in the admission rates for acute ischemic stroke.
Residential Mobility Across Local Areas in the United States and the Geographic Distribution of the Healthy Population