Background:
Transient ischemic attack (TIA) has been acknowledged as a major predictor of succeeding stroke. The data on contemporary seasonal trends in TIA hospitalizations in the United States (US) is limited with inconclusive data from other countries. We aimed to explore the TIA-related admissions and mortality trends using largest inpatient database in the US from 2010-2014.

Methods:
Using the National Inpatient Sample (NIS), and the appropriate International Classification of Diseases Ninth Clinical Modification 9 (ICD-9) CM codes, we analyzed contemporary seasonal trends in hospitalization for TIA from 2010-2014. Discharge weights were applied to achieve national estimates.

Results:
We recognized 1,150,408 weighted TIA admissions in the US through 2010-2014. We analyzed average monthly TIA related admissions and hospital mortality per season over the span of 5 years (Figure 1). Maximum monthly admissions were observed during spring (N=18926) followed by summer (N=18408), winter (N=18040) and autumn (N=17574). In-hospital mortality was documented higher during winter (N=629) and spring (N=610). In-hospital mortality was documented less during the months of autumn (N=560) and summer (N=535). 

Conclusions:
Spring and summer months witnessed highest TIA-related admissions, whereas winter and spring months documented highest case-fatality rate. Further well-designed prospective studies are warranted to comprehend the mechanism of seasonal variations affecting TIA hospitalizations and mortality in order to make preventive strikes to reduce future stroke occurrence in such high risk population.

CONTEMPORARY SEASONAL VARIATIONS IN TRANSIENT ISCHEMIC ATTACK HOSPITALIZATIONS AND IN-HOSPITAL MORTALITY IN THE UNITED STATES: AN UPDATE ON THE EXISTING LITERATURE