Chronic Bronchitis and Acute Infections as New Risk Factors for Ischemic Stroke and the Lack of Protection Offered by the Influenza Vaccination

Abstract

Background and Purpose: Acute and chronic infections may play a role in promoting complications of atherosclerotic disease. We evaluated the importance of acute infections and chronic bronchitis (CB; as a chronic inflammatory state) in several subtypes of ischemic stroke, and we investigated whether the influenza vaccination was independently associated with a reduced likelihood of stroke. Methods: A case-control study was performed on 393 consecutive ischemic stroke patients and 393 control subjects matched for age, sex and time of year. Data were collected by a structured interview that assessed risk factors, acute infections within the preceding 2 months, CB and whether they had received the influenza vaccination. Results: Infections within the 2 months before stroke onset and CB were more common among patients than control subjects [23.3 vs. 16.3% (p = 0.014) and 17.2 vs. 8.5% (p = 0.001), respectively]. After adjustment for traditional risk factors, the risk of stroke was increased in the subjects with CB (OR = 1.83, 95% CI = 1.35–2.48, p = 0.016), but not with acute infection (OR = 1.32, 95% CI = 0.98–1.78, p = 0.16). Acute infections and CB increased the risk of ischemic events in all age groups; this reached significance for patients older than 60 years. The profile of vascular risk factors was similar in patients with and without previous infections. The influenza vaccination did not prevent ischemic stroke, and it did not reduce the rate of acute previous infections in stroke patients. Conclusions: CB and infections over the previous 2 months predicted the risk of ischemic stroke. The influenza vaccination was not associated with a reduction in the incidence of stroke in our group of patients.