BackgroundOmalizumab is an efficient drug for patients with uncontrolled severe allergic asthma (SAA). However, little is known about the differences in omalizumab treatment outcomes among patients with different types of atopic sensitization. Here, we assessed the effect of sensitization to individual allergens or their combinations on the outcomes of anti-IgE therapy in patients with SAA.MethodsWe performed a post hoc analysis of data of subgroups of patients enrolled in the Czech Anti-IgE Registry (CAR). The patients were evaluated at baseline and 16 weeks and 12 months after omalizumab treatment initiation. We analyzed the dependence of primary treatment outcomes [global evaluation of treatment effectiveness (GETE) after 16 weeks of treatment, a reduction in severe exacerbation rate (ER), and an improvement in the asthma control test (ACT) result during 12 months of treatment] and secondary outcomes [a reduction in systemic corticosteroid (SCS) use, an improvement in lung functions, and a fraction of exhaled nitric oxide] of patients with SAA treated with omalizumab for 12 months on sensitization to different perennial aeroallergens. We assessed sensitization to house dust mites, molds, and pets at baseline using skin prick tests and/or specific IgE measurement (semiquantitative evaluation). We compared polysensitized patients (sensitized to all tested allergens) with monosensitized (single positivity) or partially polysensitized patients (combined positivity but not to all allergens).ResultsWe enrolled 279 patients (58.3% women, mean age 52.9 years). Omalizumab treatment presented an 82.8% response rate (according to GETE). It significantly reduced severe asthma exacerbations and SCS use, and improved the ACT result in 161 responders. We identified a subgroup of responders with distinct sensitization patterns (polysensitization to all tested perennial allergens) with higher odds of being responders (OR = 2.217, p = 0.02) and lower tendency to improve ACT result (OR 0.398, p = 0.023) and reduce ER (OR 0.431, p = 0.034) than non-polysensitized patients.ConclusionsThe clinical benefit of sensitization for patients with SAA receiving omalizumab may be particularly dependent on sensitization pattern. Polysensitized patients showed a higher tendency to be responders (GETE), but a lower tendency to improve the ACT result and reduce ER than non-polysensitized patients.