Participants
The U-BIOPRED severe asthma cohort consisted of two groups of adult severe asthmatics: non-smokers (SAn), and smokers or ex-smokers (SAs/ex) together with non-smoking mild-moderate asthma (MMA) and non-smoking healthy volunteers (HC), as previously described (15). Participants provided induced sputum samples that passed quality control for metagenomic analysis (16), at baseline and at 12-16 months later. Ethics approval was obtained at the 14 participating centres and all participants gave written informed consent (ClinicalTrials.gov identifier: NCT01982162).