Background A previous retrospective UK study (APEX I) demonstrated omalizumab significantly reduced oral corticosteroid (OCS) use, exacerbations, lung function and quality of life (QoL in severe allergic asthmatic (SAA) patients.

Aim This multi-centre observational study was conducted to confirm the observed retrospective findings prospectively.

Methods Retrospective data were collected 12 months prior to and prospective data were collected 12 months following omalizumab initiation in SAA patients ≥16 years. The primary endpoint was the change in mean daily oral corticosteroid (OCS) dosage. Secondary endpoints included changes in lung function, ACT and AQLQ scores and missed days in education/work and employment in the 12 months pre and post omalizumab initiation.

Results 258 patients were enrolled from 22 UK centres (January 2012–February 2015); mean age 44.7 years (±SD 14.2), 65% females, mean asthma duration 25.1 years (±SD 15.1) For the ITT population (n = 235), 82.4% of patients were classified as responders. At 12 months, mean daily OCS dose significantly decreased by 16% from 10.3 mg/day (±7.1) to 8.7 mg/day (±8.6) (n = 211, p < 0.001) and 61.6% of patients stopped OCS or reduced OCS dose by ≥20%. The mean (±SD) FEV₁ significantly increased from 66.9% (±19.35%) to 71.3% (±20.9%) in the 12 months post compared to pre- omalizumab initiation (p < 0.001 n = 118). Comparing the 12 months periods prior to and following initiation of omalizumab, the mean ACT score improved from 9.8 (±4.3) to 14.4 (±5.7) (n = 162, p < 0.001) and the mean AQLQ score improved from 3.2 (±1.3) to 4.4 (±1.5) (n = 161, p < 0.001). There was a significant decrease in missed days from work/education following omalizumab initiation (12 months pre-omalizumab: 14.65 days; 12 months post-omalizumab 6.22 days with p < 0.01; n = 63). For 93 patients unemployed/not in education at the study start, 72 were unemployed/not in education at study end.

Conclusions The data prospectively confirm that omalizumab is associated with significant reduction in OCS use, lung function, ACT, AQLQ and days missed from work/education.