Stroke Risk Is 39% Higher 15 Days After Flu-Like Illness

A new review of nearly 31,000 patients shows that influenza infection increases the risk for stroke regardless of urban status, sex, and race.

“Infections have been identified as risk factors for stroke. Our hypothesis was that even more common infections, such as the flu or influenza-like illness, would be a risk factor,” said lead author Amelia K. Boehme, PhD, assistant professor of epidemiology in neurology for Vagelos College of Physicians and Surgeons at Columbia University in New York City.

“We are not sure of the exact mechanism behind flu and stroke. We believe it to be similar to the mechanism behind other infections and stroke, but more research is needed to determine the exact mechanism,” Dr Boehme said.

To better understand the influenza-stroke association, Dr Boehme and colleagues from New York reviewed 2012-2014 inpatient and outpatient data from the New York Statewide Planning and Research Cooperative System (SPARCS).

“We had access to about 97% of New York State hospitalizations that are linkable using a deidentified patient identifier, regardless of insurance status. This enabled us to investigate whether people were readmitted for stroke after an influenza-like illness,” Dr Boehme said.

With this data, the researchers estimated the odds of hospitalization for ischemic stroke after hospitalization for influenza. Analyses were stratified by urban and rural status based on residential zip code, sex, and race.

In 2014, 30,912 individuals were hospitalized with an ischemic stroke and were included in the analysis. A total 49% of participants were men, 20% were black, and 84% were from urban neighborhoods. The mean age of participants was 71.9 years.

Results of this analysis showed that within 15 days of influenza inflection, the odds of experiencing a stroke increased by 39%. This association remained over 365 days and was not significantly associated with urbanicity, sex, or race.

“These results supported our hypothesis that even common infections can increase the risk of stroke. We plan to continue researching the relationship, and our next steps are to start testing hypotheses that will help us tease out what the mechanism behind this relationship is,” Boehme concluded.

—Amanda Balbi

Reference:

Alvord T, Kulick E, Cannine M, Elkind M, Boehme A. Influenza-like illness and risk of stroke in New York State. Paper presented at: International Stroke Conference 2019; February 6-8, 2019; Honolulu, HI. https://www.ahajournals.org/doi/10.1161/str.50.suppl_1.189. Accessed January 30, 2019.