UTIs linked to 5 times the risk of ischemic stroke

Infections—most notably urinary tract infections (UTIs)—were linked to a significantly increased risk of acute ischemic stroke in a recent study out of the Icahn School of Medicine at Mount Sinai.

In launching their study, corresponding author Mandip S. Dhamoon, MD, DrPH, an associate professor of neurology at the Icahn School, and colleagues aimed to examine the differential associations between infections in different body systems and patients’ subsequent risk of ischemic stroke, subarachnoid hemorrhage (SAH) and intracerebral hemorrhage (ICH). The team hypothesized there would be a gradient of association between infection and risk of stroke—an association that would grow stronger the closer a patient got to a stroke event.

“Acute infections have been studied as potential triggers of stroke,” Dhamoon and co-authors wrote in Stroke, where they published their findings this week. “However, infections in different organ systems have been rarely examined comparatively in the same study, and studies failed to differentiate SAH and ICH.”

The authors used the New York State Inpatient Databases and Emergency Department Databases to identify index hospitalizations for acute ischemic stroke, ICH and SAH between 2006 and 2013, as well as emergency department visits and hospitalizations for infections including UTIs, septicemia, and skin, abdominal and respiratory infections. A case cross-over analysis revealed the link between each type of infection and stroke in the 7, 14, 30, 60, 90 and 120 days leading up to a patient’s ischemic event.

Each infection type was associated with some increased likelihood of acute ischemic stroke, Dhamoon et al. reported, but UTIs led the charge. UTI was linked to a more than 5 times increased risk of stroke in the 7 days before a patient’s event, while the same infection was associated with a smaller 1.8-fold increased risk of ICH in the 14-day exposure period and a 1.54-fold increased risk of ICH in the 120-day exposure period. 

The only infection tied to SAH was respiratory, the authors said, which was also the most common infection in the study population. Respiratory infections were linked to a 3.67-fold increased risk of stroke in the 14-day window and a 1.95-fold increased risk in the 120-day window.

“We...observed a gradient of decreasing magnitudes of association with longer time periods across various infection types and stroke subtypes, supporting the concept of infection as a trigger of these events with a greater potential influence over a shorter time window,” Dhamoon et al. wrote.

The team said there could be several explanations for why infection triggers stroke, including increases in circulating leukocytes contributing to atherogenesis and thrombogenesis; increased platelet activation; increased risk of deep vein thrombosis leading to paradoxical embolism; elevated fibrinogen, clotting factors and cytokines; and the metabolism and function of endothelial cells favoring atherosclerosis.

“More research is needed on potential interventions, such as vaccination or antibiotic regimens, or intensive antithrombotic treatments, to not only treat the infection but also potentially reduce thrombotic and bleeding risk,” Dhamoon and co-authors said.