Differences between asthmatics and non-asthmatics hospitalised with influenza A infection

Myles, Puja, Nguyen-Van-Tam, Jonathan S., Semple, Malcolm G., Brett, Stephen J., Bannister, Barbara, Read, Robert C., Taylor, Bruce L., McMenamin, Jim, Enstone, Joanne E., Nicholson, Karl G., Openshaw, Peter J. and Lim, Wei Shen (2012) Differences between asthmatics and non-asthmatics hospitalised with influenza A infection. European Respiratory Journal. (doi:10.1183/09031936.00015512). (PMID:22903963)

Abstract

Asthmatics hospitalised because of influenza A infection are less likely to require intensive care or die compared to non-asthmatics. Reasons for this are unknown.A retrospective analysis of data on 1,520 patients admitted to 75 UK hospitals with confirmed influenza A/H1N1 2009 infection. A multivariable model was used to investigate reasons for the association between asthma and severe outcomes (intensive care unit support or death).Asthmatics were less likely than non-asthmatics to have severe outcome (11.2% vs 19.8%, unadjusted OR 0.51, 95%CI 0.36 to 0.72) despite a greater proportion requiring oxygen on admission (36.4% vs 26%, unadjOR 1.63) and similar rates of pneumonia (17.1% vs 16.6%, unadjOR 1.04). The results of multivariable logistic regression suggest the association of asthma with outcome (adjOR 0.62, 95%CI 0.36 to 1.05, p=0.075) is explained by pre-admission inhaled corticosteroid use (adjOR 0.34, 95%CI 0.18 to 0.66) and earlier admission (?4 days from symptom onset) (adjOR 0.60, 95%CI 0.38 to 0.94). In asthmatics, systemic corticosteroids were associated with a decreased likelihood of severe outcomes (adjusted OR 0.36, 95% CI 0.18 to 0.72).Corticosteroid use and earlier hospital admission explained the association of asthma with less severe outcomes in hospitalised patients.

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Contributors

Author: Robert C. Read

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