Rachel Forman, MD

Sebastian S, Stein LK, Dhamoon MS. Infection as a Stroke Trigger: Associations Between Different Organ System Infection Admissions and Stroke Subtypes. Stroke. 2019

When I read the title of this article the first thing that came to mind was endocarditis. This is the infection type that we typically worry about when a stroke patient is febrile or appears to have an infection. This article, titled “Infection as a Stroke Trigger,” looks further into the connection between other types of infections and the risk of stroke.

The study evaluates the link between different types of stroke (ischemic stroke, intracerebral hemorrhage, and subarachnoid hemorrhage) and various infections. Specifically, it looked at urinary tract infections (UTIs), skin infections, septicemia, abdominal infections, and respiratory infections. The group hypothesized that there would be a temporal relationship between the risk of stroke and infection. The data was obtained from a New York State database between 2006 and 2013. Statistical analysis was done using a case crossover analysis using control periods one year prior. 

The data showed that every infection type was associated with an increased likelihood for acute ischemic stroke, greatest with UTIs (OR 5.23 at 7 days). The risk was greatest in the time frame closest to the infection, and the risk decreased with longer time out from the infection. Additionally, they found that there was a significant association between septicemia and intracerebral hemorrhage. There were fewer exposures with subarachnoid hemorrhage, and only respiratory infections showed an association, likely because of limited power for the other infections. 

The paper then went on to discuss potential mechanisms responsible for the elevated stroke risk from infections. These included an increase in circulating leukocytes contributing to atherogenesis and thrombogenesis; increased platelet activation; increased risk of deep vein thrombosis (DVT) with immobilization; and increased infectious cascade factors. This was a good overview and reminder to think more broadly when considering stroke etiologies.

Some strengths of the study mentioned included using a case-crossover design and using a large data set. Some limitations included relying on ICD coding to identify these conditions. The authors end with noting that more research is needed on vaccinations and antibiotic regimens. This brings up a great point in that when treating infections, the risk of a thrombotic state or bleeding risk as it pertains to stroke is often not considered. As more information is gathered on this topic, it will be helpful to make providers aware of this risk and what complications they may come across during the infectious treatment course.