International Severe Asthma Registry: Mission Statement. - Canonica GW; Alacqua M; Altraja A; Backer V; Bel E; Bjermer L; Bjornsdottir US; Bourdin A; Brusselle GG; Christoff GC; Cosio BG; Costello RW; et al. (Chest 2020, 2020)