The role of small airways disfunction in EGPA

Small airways disfunction (SAD) is a trait of asthma, with a prevalence >90% and a significant impact on exacerbation risk and symptom control. Asthma is a frequent manifestation of EGPA and >57% of EGPA patients have a severe asthma, as defined by ERS/ATS. Little is known about functional characteristics of asthma associated with EGPA, included SAD prevalence. The aim of this multicentric retrospective study was to evaluate the prevalence of SAD, defined by any alteration in FEF25-75, R5-19, AX and X5, in asthmatic patients with EGPA and to compare their functional characteristics with a matched group of asthmatic patients with severe eosinophilic asthma (SEA). The secondary aim was to evaluate the impact of SAD disease control (ACT/ACQ7) in the two conditions. We present results from 35 patients, 16 with EGPA and 19 with SEA, matched by sex, age and anthropometric characteristics. 27 patients were on biologic therapy for severe asthma (14 in SEA group and 13 in EGPA group). We found similar functional characteristics between SEA and EGPA groups with a SAD prevalence 66% in the whole sample, 68% in EGPA group and 63% in SEA group (p=0.736). We confirmed the impact of SAD on asthma control, with ACT values significantly lower (p=0.012) in patients with SAD [24(22-25) vs 22(16-24)] both in EGPA [24(22-25) vs 22(16-24)] and SEA patients [25(25-25) vs 22(17-25)]. Similar results were found for ACQ7, significantly higher (p=0.017) in patients with SAD [0.7(0.28-1.50) vs 0(0.00-0.01)] independently from presence of EGPA [0.7(0.28-1.50) vs 0(0.00-0.01)] or SEA [0.6(0.1-1.5) vs 0.0(0.0-0.1)]. In conclusion, asthma in EGPA is comparable with SEA, both in terms of SAD prevalence and negative impact on asthma disease control (ACT/ACQ7).