NEW ORLEANS – There may be a correlation between infection and stroke in children, according to research presented at the International Stroke Conference.

Acute infection is considered to be a risk factor for stroke in adults, so researchers from the University of California, San Francisco, decided to study whether it might also be a potential risk in children, who experience frequent infections.

Stroke, however, is still extremely rare in children: The incidence of acute arterial ischemic stroke is 2.4 per 100,000 children annually in the United States. A large proportion of those cases have no known cause, said Nancy K. Hills, Ph.D., assistant adjunct professor of neurology at UCSF, at a press briefing. Many of those children, however, have an underlying arteriopathy.

Dr. Hills and her colleagues found that children who had a stroke were eight times more likely to have visited a health provider for an infection within 1 month before the stroke, compared with controls. More than 1 month before the stroke, however, there was no difference in the number of visits for infection between cases and controls. The researchers could not prove a direct link between infection and stroke. "We really believe it’s not the infection that’s causing the stroke," Dr. Hills said.

"It’s not something that parents of healthy children need to worry about," she said, adding that the infections are "probably a trigger for something else." The researchers believe that the children who had infection and stroke "probably have some underlying predisposition that causes them to have an unusual response to a common infection."

The retrospective study examined medical records for 2.5 million children – aged 29 days to 19 years – who were members of Kaiser Permanente from 1993 to 2007. The investigators identified 126 acute ischemic strokes, and then randomly selected 378 age-matched controls (three controls per case) from the Kaiser population. The median age was 10.5 years, and there was a relatively similar mix of male and females. All races were proportionately represented, said Dr. Hills.

The researchers looked at both diagnosed infections and symptoms that were indicative of infection. Any history of infection after a stroke diagnosis was excluded. Once the index stroke was established, the researchers categorized infectious visits according to time frames: 0-2 days, 3-7 days, 8-28 days, 1-3 months, 3-6 months, 6-12 months, and 12-24 months before the stroke.

They found that children who had a stroke were much more likely to have had a visit for infection within 1 month of the index stroke (odds ratio, 8.37). The odds ratio increased to 182 for a visit for infection within 2 days of the stroke. Twenty-nine percent of those who had a stroke had a visit in the 2 days prior to the stroke, compared with 1% of controls for the same dates. In the 3- to 7-day window, 13% of children who had a stroke had an infection, compared with 2% of controls.

The authors concluded that the risk of stroke is substantially elevated within the week after a visit for infection, but that it is likely that these children have some susceptibility to stroke, and that the infection puts them in a prothrombotic state, Dr. Hills said at the meeting, which was sponsored by the American Heart Association.

She pointed out several limitations to the study, including the fact that the number of infections in both the cases and controls was likely underestimated. Also, the infections were not generally confirmed by lab data; they were based on empirical diagnoses.

The study was funded by the National Institute of Neurological Disorders and Stroke. The authors reported no relevant financial conflicts.