Recent respiratory infection predicts stroke

People with recent respiratory infections may be at higher risk of stroke, according to a study published in the current issue of the journal Stroke.

Studies have found that infections, especially those of the respiratory tract and gum tissues, are associated with vascular events causes by blockage of blood flow to the tissues (ischemia), lead author Dr. Maria Cristina Zurru, of Hospital Italiano de Buenos Aires, told Reuters Health. "Prior investigations from the United States and Europe have demonstrated that up to 35 percent of patients with ischemic stroke have a history of infection within the previous months."

However, "at this time the role of the infection as an independent stroke risk factor is not well established," Zurru noted.

She and colleagues studied 105 stroke patients and 354 randomly selected healthy subjects (controls) in a Buenos Aires healthcare system. The subjects were matched by age, sex, and major cardiovascular risk factors.

The stroke patients were consecutive subjects with atherothrombotic ischemic stroke admitted to a hospital between December 2006 and October 2007. The authors collected data from the preceding year on respiratory, urinary, and abdominal infections, and determined the average white blood cell count.

Overall, 29 percent of cases had a history of infection during 1 year, compared with 13 percent of controls. This was driven by community-acquired respiratory tract infections (19 percent versus 6 percent in the stroke patients and the controls). No differences were observed between patients and controls for other types of infection.

Respiratory tract infections were the most prevalent type of infection during the 3 months before the ischemic event, occurring in 17 percent of patients versus 4 percent of controls. Adjusting for major vascular risk factors demonstrated that history of respiratory tract infection in the previous 12 months was associated more with stroke patients than controls.

Patients had a significantly higher white blood cell counts than did controls. There were no differences between the groups in total cholesterol and high-density lipoprotein cholesterol. Cases had higher low-density lipoprotein cholesterol.

"In our population, recent respiratory infections were significantly associated with atherothrombotic stroke, suggesting that prompt identification and treatment of individuals with or at risk for these infections may mitigate the burden from this type of stroke," Zurru told Reuters Health.

SOURCE: Stroke, June 2009.