Eosinophilic airway inflammation and exacerbations of COPD: a randomised controlled trial

Evidence suggests that eosinophilic airway inflammation is important in the pathogenesis of severe chronic obstructive pulmonary disease (COPD) exacerbations. The present authors tested the hypothesis that a management strategy that aims to reduce sputum eosinophil counts is associated with a reduction in exacerbations of COPD. A total of 82 patients with COPD were randomised into two groups. One group was treated according to traditional guidelines (British Thoracic Society (BTS) group) and the other (sputum group) was treated with the additional aim of minimising eosinophilic airway inflammation, assessed using the induced sputum eosinophil count. The primary outcome was exacerbations, which were categorised as mild, moderate or severe. The frequency of severe exacerbations per patient per year was 0.5 and 0.2 in the BTS and sputum groups, respectively (mean reduction 62%). The majority of this benefit was confined to patients with eosinophilic airway inflammation. There was no difference in the frequency of mild and moderate exacerbations. The average daily dose of inhaled or oral corticosteroids during the trial did not differ between the groups. Out of 42 patients in the sputum group, 17 required regular oral corticosteroids to minimise eosinophilic airway inflammation. A management strategy that aims to minimise eosinophilic airway inflammation, as well as symptoms, is associated with a reduction in severe exacerbations of chronic obstructive pulmonary disease.