Association of symptoms of chronic bronchitis and frequent flu-like illnesses with stroke.

Abstract

Acute and several chronic infectious diseases increase the risk of stroke. We tested the hypothesis that chronic bronchitis and frequent flu-like illnesses are independently associated with the risk of stroke or transient ischemic attack (TIA). We assessed symptoms of chronic bronchitis, frequency of flu-like illnesses, and behavior during acute febrile infection in 370 consecutive patients with ischemic or hemorrhagic stroke or TIA and 370 age- and sex-matched control subjects randomly selected from the population. Cough with phlegm during > or = 3 months per year (grade 2 symptoms of chronic bronchitis) was associated with stroke or TIA independent from smoking history, other risk factors, and school education (odds ratio [OR] 2.63, 95% confidence interval [CI] 1.17 to 5.94; P=0.021). There was also an independent association between frequent flu-like infections (>2 per yr) and stroke/TIA (OR 3.54; 95% CI 1.52 to 8.27; P=0.003). Simultaneous assessment of chronic bronchitis and frequent flu-like infections did not attenuate the effect of either factor. Patients reported more often than control subjects to continue to work despite febrile infection (OR 3.68, 95% CI 1.80 to 7.52, multivariate analysis). Our results suggest that chronic bronchitis is among those chronic infections that increase the risk of stroke. Independent from chronic bronchitis, a high frequency of flu-like illnesses may also be a stroke risk factor. Infection-related behavior may differ between stroke patients and control subjects.