Anthrax Vaccine Adsorbed and Risk of Idiopathic Atrial Fibrillation in the United States Military, 1998-2005

Learning Objectives for this Presentation:
By the end of the presentation participants will be able to better understand the possible relationship between idiopathic atrial fibrillation and anthrax vaccine adsorbed (AVA).

Background:
Atrial fibrillation is a significant public health problem and is associated with substantial morbidity and mortality. Evaluating the possible relationship between idiopathic atrial fibrillation and AVA is a priority topic of the Vaccine Analytic Unit (VAU) at CDC. Based on several reports to the Vaccine Adverse Event Reporting System (VAERS), it has been hypothesized that there may be a relationship between atrial fibrillation and AVA, and influenza and smallpox vaccines.

Objectives:
To explore a possible association between idiopathic atrial fibrillation and AVA, and influenza and smallpox vaccines, among U.S. military personnel serving worldwide.

Methods:
We conducted a retrospective population-based cohort study among active duty U.S. military personnel from January 1, 1998 through December 31, 2005 using the Defense Medical Surveillance System (DMSS), a longitudinal surveillance database. ICD-9-CM codes were used to identify individuals diagnosed with atrial fibrillation. Electronic records were then screened to eliminate subjects with a history of prior atrial fibrillation or with evidence of an identifiable underlying risk factor. We used Poisson regression to estimate the risk between vaccine exposure and atrial fibrillation.

Results:
Approximately 2.59 million individuals were studied for 9,850,412 person-years of service. During follow up, 942,701 (36.4%) individuals received at least one dose of AVA. We found no elevated risk of diagnosed idiopathic atrial fibrillation associated with AVA (adjusted risk ratio= 0.996; 95% confidence interval= 0.892, 1.112; p=0.87). Similarly, no elevated risk was observed for diagnosed idiopathic atrial fibrillation associated with influenza or smallpox vaccines given during military service.

Conclusions:
We identified no increased risk of diagnosed idiopathic atrial fibrillation associated with AVA, influenza, or smallpox vaccination in our study population using only coded diagnosed cases.