Association between episodes of upper respiratory infection and exacerbations in adult patients with asthma

Background. Asthma has several phenotypical features, including recurrent exacerbations and recurrent episodes of upper respiratory infection (URI). Purpose. A retrospective study was performed to identify the characteristics of adult patients with recurrent exacerbations of asthma, especially in association with recurrent episodes of URI. Methods. Information was collected using a self-administered questionnaire given to 7070 patients in autumnwinter 2006, 4859 patients in springsummer 2007, and 4452 patients in autumnwinter 2007. The patients reported the degree of symptoms and the frequency of febrile episodes of URI and exacerbations. Severe exacerbations were defined as a self-report of asthma-related hospitalization, an emergency department visit, or a requirement for systemic corticosteroids. Recurrent febrile URI and exacerbations were defined as two or more episodes within the previous 6 months. A Poisson regression model was used to identify the factors that were predictors of a risk for exacerbations. Results. Of the 6266 patients who completed the questionnaire, the frequencies of febrile URI and episodes of severe exacerbations were 1.54 and 0.54 per subject per year, respectively. Logistic regression analysis showed that an older age [odds ratio (OR): 1.57; 95% confidence interval (CI): 1.152.13], female sex (OR: 1.58; 95% CI: 1.202.08), recurrent febrile episodes of URI (OR: 2.68; 95% CI: 1.474.91), a history of previous exacerbation within 1 year (OR: 1.74; 95% CI: 1.282.34), disuse of inhaled corticosteroids (ICSs) (OR: 2.63; 95% CI: 1.684.12), and disuse of add-on leukotriene receptor antagonists (LTRAs) (OR: 1.42; 95% CI: 1.061.74) were independently associated with moderate to severe symptom-severity. Poisson regression analysis showed that the independent factors that contributed to the frequency of recurrent severe exacerbations were female sex (regression coefficient β = 0.62, p <.01), an episode of sputum with coughing (β = 1.23, p <.01), nocturnal awakening (β = 1.22, p <.01), and severe exacerbation (β = 0.78, p <.01) within the previous 6 months. Conclusion. Symptom-severity of asthma and the frequency of severe exacerbations were associated with previous exacerbations and susceptibility to URI.