Trend and Characteristics of Anaphylaxis-related Hospitalization From 2009-2011: Data from the Nationwide Inpatient Sample
Saturday, March 3, 2018
South Hall A2 (Convention Center)
Pragya Shrestha, MD, Rashmi Dhital, MD, Dilli Poudel, MD, Paras Karmacharya, MD, Anthony Donato, MD

Although anaphylaxis is a well-recognized life-threatening systemic condition, data available in the literature is limited regarding its prevalence and characteristics. Prior studies have suggested an increasing trend of food-related anaphylaxis over the course of years, however no study had detailed the various causes of anaphylaxis and its seasonal trend in large population database.


NIS database was used to identify patients admitted with anaphylaxis diagnosis between 2009-2011 using appropriate ICD-9-CM codes (995.0, V13.81, 999.41-999.42, 999.49, 995.0, 995.60-995.69). Monthly distribution of anaphylaxis with stratification per age group, race, sex and region was calculated in relation to food, serum, venom and medications. Edwards recognition with estimation of cyclic trend method and Z-test were used to compare the seasonal trend (peak-to-low ratio).


An estimated 84,756 anaphylaxis-related hospitalizations occurred in the US from 2009-2011. Highest incidence was observed during summer months (July, peak/low ratio 1.896, 95% CI 1.857-1.937, p<0.001) across all age-groups and regions, which held true even after stratifying cases based on extrinsic trigger factors (food, serum, venom). However, the peak incidence of medication-associated anaphylaxis occurred during the winter months (December, peak/low ratio 1.750, 95% CI 1.687-1.816, p<0.001).


Anaphylaxis from extrinsic trigger factors and medicines seem to have specific but different seasonal variations. The hypothesis that increasing usage of medications to treat diseases with cyclic seasonal prevalence in winter would need to be explored in further studies, but a deeper understanding of these trends could aid prevention efforts.