• A Bjerregaard, I A Laing, V Backer, A Sverrild, S-K Khoo, G Chidlow, C Sikazwe, D W Smith, P Le Souëf, and C Porsbjerg.
• Respiratory Research Unit, Bispebjerg University Hospital, Copenhagen, Denmark.
• Clin. Exp. Allergy. 2017 Aug 1; 47 (8): 1007-1013.

BackgroundThe major trigger of asthma exacerbations is infection with a respiratory virus, most commonly rhinovirus. Type 2 inflammation is known to be associated with an increased risk of exacerbations in general. Whether type 2 inflammation at baseline increases the risk of future virus-induced exacerbations is unknown.ObjectiveTo assess whether type 2 inflammation is associated with an increased risk of virus-induced exacerbations of asthma.MethodsStable asthmatics had spirometry, skin prick test, measurement of FeNO and sputum induced for differential cell counts. Patients were followed up for 18 months, during which they were assessed at the research unit when they had symptoms of an exacerbation. Nasal swabs collected at these assessments underwent viral detection by PCR.ResultsA total of 81 asthma patients were recruited, of which 22 (27%) experienced an exacerbation during the follow-up period. Of these, 15 (68%) had a respiratory virus detected at exacerbation. Sputum eosinophils >1% at baseline increased the risk of having a subsequent virus-induced exacerbation (HR 7.6 95% CI: 1.6-35.2, P=.010) as did having FeNO >25 ppb (HR 3.4 95% CI: 1.1-10.4, P=.033).Conclusion And Clinical RelevanceEstablished type 2 inflammation during stable disease is a risk factor for virus-induced exacerbations in a real-life setting. Measures of type 2 inflammation, such as sputum eosinophils and FeNO, could be included in the risk assessment of patients with asthma in future studies.© 2017 John Wiley & Sons Ltd.

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