Clinical outcome of eosinophilic airway inflammation in chronic airway diseases including nonasthmatic eosinophilic bronchitis

Abstract

We enrolled patients with confirmed sputum eosinophilia who had visited our tertiary referral hospital between 2012 and 2015. We evaluated the incidence and predictors of exacerbations in patients with nonasthmatic eosinophilic bronchitis (NAEB), and investigated predictors of improvement in eosinophilic inflammation in chronic airway diseases with or without persistent airflow limitation. In total, 398 patients with sputum eosinophilia were enrolled. Of these, 152 (38.2%) had NAEB. The incidence rate of exacerbations requiring treatment with antibiotics, systemic corticosteroids, or hospital admission was 0.13 per patient-year (95% CI, 0.06-0.19) in NAEB. Inhaled corticosteroid (ICS) did not affect the risk of exacerbations, even in an analysis of propensity score. One hundred seventysix patients had chronic airway diseases; in 37 of these (21.0%), sputum eosinophilia had improved at the 1-year follow-up. Patients who had persistent airflow limitation were less likely to show an improvement in eosinophilic inflammation (aOR, 0.26; 95% CI, 0.09-0.77) when they were treated with ICSs for less than 75% of the follow-up days. Exacerbations requiring systemic corticosteroids, antibiotics, or hospitalization did occur, although infrequently, in NAEB patients. Among patients with chronic airway diseases, those with persistent airflow limitation were less likely to show an improvement in eosinophilic airway inflammation.Nonasthmatic eosinophilic bronchitis (NAEB) usually presents with corticosteroid-responsive chronic cough; in fact, the condition is diagnosed in 13% to 33% of patients with chronic cough referred for specialist opinion [1][2][3][4] . Patients with NAEB have eosinophilic airway inflammation, which manifests as sputum eosinophilia similar to that in asthma. However, these patients lack evidence of variable airflow limitation or airway hyperresponsiveness. Previous longitudinal studies on NAEB have focused on the prognosis concerning relapse and the development of chronic airflow obstruction [5][6][7] . However, NAEB patients could have respiratory symptoms other than cough, such as chest tightness with wheezing, shortness of breath, and sputum production [8][9][10] , and treatment with systemic corticosteroids is occasionally required to relieve these symptoms 11 . No studies have yet investigated the incidence and predictors of acute exacerbations, defined as worsened respiratory symptoms requiring systemic treatment, in this condition.Sputum eosinophilia is also present in 38% to 44% of patients with persistent airflow limitation, including those with chronic obstructive pulmonary disease (COPD) 12,13 . Patients with COPD who show eosinophilic airway inflammation respond better to inhaled corticosteroids (ICSs) 12,14 and systemic corticosteroids 13,15 , as do those with asthma-COPD overlap syndrome (ACOS) 16 . However, it is not yet clear whether the outcome of eosinophilic airway inflammation differs depending on whether persistent airflow limitation-a characteristic of COPD-is present.

Perspectives on chronic cough in Korea

“…Progressive forced expiratory volume in one second (FEV1) reduction >20% was observed in three of five patients with recurrent eosinophilic bronchitis, but not in those patients without recurrent eosinophilia (69). In a retrospective cohort study of Korean patients, chronic airflow obstruction developed in five of 48 patients with eosinophilic bronchitis, and exacerbations requiring systemic corticosteroids, antibiotics, or hospitalization occurred in 15 patients (70). However, in a prospective study of Chinese patients with eosinophilic bronchitis (followed for > one year; median, 4.1 years), relapsing cases were reported in about 60% of the patients, and mild asthma developed in 5.7%, whereas progressive decline in lung function was not observed (71).…”