Bronchiectasis and airway eosinophilia in severe asthma—is there an association?

<b>Introduction:</b> Bronchiectasis is common in severe asthma. But, whether bronchiectasis in these patients is linked to eosinophilic airway inflammation is not well understood. <b>Aim:</b> We examined the association between eosinophilia and bronchiectasis in severe asthma. Further, to describe whether eosinophilia is a risk factor for exacerbations and loss of lung function in patients with severe asthma and bronchiectasis? <b>Methods:</b> Patients with severe asthma (n=108) according to ERS/ATS guidelines were recruited for a systematic evaluation across four Danish outpatient clinics. Spirometry values, sputum cell differential and number of exacerbations in the last year were collected. Bronchiectasis was evaluated using high-resolution computed tomography. Eosinophilia and neutrophilia were defined as ≥3% eosinophils and &gt;61% neutrophils in sputum, respectively. <b>Results:</b> Overall, 31.5% of patients with severe asthma had bronchiectasis. Among those with eosinophilia 58.6% had bronchiectasis (p=0.01). Conversely, in patients with bronchiectasis 56.7% had eosinophilia (OR 4.8 (1.8-12.6)). There were no association between bronchiectasis and sputum neutrophilia (OR 1.2 (0.5-2.9). Patients with bronchiectasis and eosinophilia had lower lung function (FEV1% 60.4±25.3 vs. 81.3±20.2; p=0.02) and were more obstructive (FEV1/FVC 0.59±0.17 vs. 0.72±0.86; p=0.01) compared with those with no sputum eosinophilia. In patients with bronchiectasis exacerbations did not differ according to sputum eosinophilia (2(IQR 4) vs. 1(IQR 3); p=0.48. <b>Conclusion:</b> Bronchiectasis in severe asthma is associated with eosinophilic airway inflammation—and eosinophilic bronchiectasis in severe asthma seems related to increased risk of loss of lung function.