BackgroundPhase III regulatory trials show that anti-IL 5 biologics efficiently reduce exacerbations and use of maintenance oral corticosteroids (mOCS) in patients with severe eosinophilic asthma. However, patients eligible for these trials differ significantly compared to real life severe asthma populations. Therefore, our aim was to explore efficacy in a real-life setting. The Danish Severe Asthma Register (DSAR) is a complete, nationwide register that comprises all Danish patients on biological therapy for severe asthma.MethodsThis prospective study identified patients in DSAR who were complete responders to anti IL5 biologics after one year of treatment. A complete response was defined as resolution of the parameter setting the indication, i.e. recurrent exacerbations and/or use of mOCS.ResultsA total of 289/502 (58%) were complete responders to anti-IL5 biologics after 12 months. Complete responders had greater improvements in FEV1 and Asthma Control Questionnaire (ACQ) compared to non-complete responders (Δ 210 mL versus Δ 30 mL, p<0.0001) and (Δ-1.04 versus Δ-0.68, p=0.016), respectively. A complete response was predicted by age at onset, less severe disease at baseline (i.e. no mOCS and lower ACQ score) and higher blood eosinophils.ConclusionMore than half of Danish patients treated with anti-IL5 biologics for severe asthma achieve a complete response to treatment thereby becoming free from asthma exacerbations and need for mOCS. Complete responders also achieved superior effects on lung function and symptoms compared to non-complete responders.

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