High fractional exhaled nitric oxide and sputum eosinophils are associated with an increased risk of future virus-induced exacerbations -NDASH- a prospective cohort study

Abstract

Background

The 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.

Objective

To assess whether type 2 inflammation is associated with an increased risk of virus-induced exacerbations of asthma.

Methods

Stable 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.

Results

A 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=0.010), as did having FeNO > 25 ppb (HR 3.4 95% CI 1.1-10.4, p=0.033).

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