Clinical characteristics and biological treatment responses of patients with late-onset asthma phenotype.

Background: The data on subphenotypes and treatment responses to biologicals in late-onset asthma (LOA) is limited. This study aims to compare the clinical characteristics and treatment responses in severe asthma patients receiving biological treatments, categorized into early-onset asthma (EOA) and LOA groups. Methods: Patients treated with omalizumab or mepolizumab for at least six months at a tertiary care adult allergy clinic between December 2015 and December 2023 were included. Patients with persistent respiratory symptoms starting at age ≥40 years were categorized as LOA, while those with onset <40 years were categorized as EOA. Changes in Asthma Control Questionnaire (ACQ-6) scores, forced expiratory volume in one second (FEV1) percentages, and blood eosinophil counts were assessed at baseline and 6 months. The percentage change in FEV1 (liters) at 6 months relative to baseline was measured. Clinical remission rates were evaluated in those completing one year of treatment. Results: Among 87 patients, 38 (43.7%) had LOA and 49 (56.3%) had EOA. Of these, 22 (25.3%) received omalizumab and 65 (74.7%) received mepolizumab, with a mean treatment duration of 24.7 (±19.7) months. LOA patients had higher obesity rates and tobacco consumption compared to EOA patients (p = 0.041 and p = 0.024, respectively). There were no significant differences between LOA and EOA groups in ACQ scores, FEV1 percentage, the percentage change in FEV1 in liters and eosinophil counts (p = 0.531, p = 0.219, p = 0.632, p = 0.700, respectively). Within LOA patients, ACQ scores did not significantly differ between those treated with omalizumab and mepolizumab (p = 0.801). At 6 months, eosinophil counts significantly decreased with mepolizumab but not with omalizumab (p = 0.002). Conclusion: Biological treatment responses were similar between LOA and EOA groups. Omalizumab and mepolizumab showed comparable efficacy, with the exception of eosinophil count changes in LOA patients.