Inhaled corticosteroids and influenza A (H1N1) viral pneumonia

Background: Recent studies suggest that the use of inhaled corticosteroids (ICS) may be associated with a higher risk of pneumonia in patients with COPD. However it is unclear if ICS are associated with pneumonia risk in patients with influenza A (H1N1) infection. Therefore, our aim was to examine the association of prior outpatient ICS therapy with influenza pneumonia in patients with confirmed influenza A (H1N1) 2009 infection presenting to a University Hospital in Madrid. Methods: We included patients ≥16 yrs of age with influenza A (H1N1) virus infection diagnosed by real-time reverse-transcriptase polymerase chain reaction (RT-PCR) and assessed the association of ICS exposure with viral pneumonia using covariate-adjusted regression model. Results: We identified 121 subjects with a diagnosis of influenza A (H1N1) virus infection who had a chest radiograph ordered. 71 (59%) had pneumonia, 17 (14%) acute exacerbation of COPD, 18 (15%) acute asthma exacerbation and 15 (12%) an influenza syndrome with no other diagnosis. 15% of subject with viral pneumonia were on previous ICS compared with 32% of the subject with influenza infection without pneumonia (p 0.03). In regression analyses, outpatient ICS therapy was associated with lower pneumonia in patients with influenza A (H1N1) infection (OR 0.29; 95% CI 0.11-0.77). When we look for a possible class effect, the association was only found with fluticasone (OR 0.09; 95% CI 0.02-0.47, p= 0.004). Conclusion: In our cohort viral pneumonia was quite common and the inhaled corticosteroid fluticasone may be associated with a lower risk of pulmonary infiltrates in patients with influenza A (H1N1) infection.