Recent respiratory infection predicts atherothrombotic stroke: case-control study in a Buenos Aires healthcare system

Increasing evidence links infections to atherosclerosis. Case-control and cohort studies have found that infections, especially respiratory and dental, are associated with coronary heart disease. However, data on the association of infections with cerebrovascular disease are limited, especially beyond Europe and the United States. We assessed the relationship between recent infections and atherothrombotic disease in a South American cohort.

We conducted a case-control study of 105 cases and 354 control subjects in a Buenos Aires healthcare system matched by age (mean age, 73.2+/-12.3 and 72.9+/-12.8 years), sex, and major cardiovascular risk factors. Cases were patients hospitalized with atherothrombotic ischemic stroke from December 2006 to October 2007. Control subjects were randomly assigned from an electronic outpatient database. Data from the preceding year on inpatient and ambulatory respiratory, urinary and abdominal infections as well as peripheral white blood cell count were collected.

Infections were more frequent in cases than control subjects (29% versus 13%; OR, 2.6; 95% CI, 1.4 to 4.5; P=0.0004); however, this was driven by community-acquired respiratory tract infections (19% versus 6%; OR, 3.9; 95% CI, 1.9 to 8; P<0.001) because there were no differences between cases and control subjects for other types of infection. Respiratory tract infections were the most prevalent type of infection during the 3 months before an atherothrombotic ischemic event, occurring more in cases compared with control subjects (17% versus 4%; OR, 5; 95% CI, 2.2 to 11.3; P<0.001). In multivariable analysis adjusting for major vascular risk factors, history of respiratory infection in the prior year was associated more with cases than control subjects (OR, 4.9; 95% CI, 2.3 to 10.2;P<0.001). White blood cell count was slightly higher in cases versus control subjects (7602+/-2058 versus 7121.6+/-1947, P=0.01).

In this South American cohort, recent respiratory tract 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.