Relapse rates and associated risk factors following omalizumab treatment in adolescents with chronic spontaneous urticaria

Background Omalizumab is an effective treatment option for antihistamine‐resistant chronic spontaneous urticaria (CSU) patients. This study aimed to evaluate relapse in patients after completing omalizumab treatment and identify associated risk factors. Methods Patients aged 12–18 years diagnosed with CSU who received omalizumab therapy between 2015 and 2023, whose treatment ceased with complete remission by December 2024. Results This study consisted of 59 patients with a median (interquartile) age of 14.0 (12.0–16.0) years, of whom 49.2% were female. Post‐treatment relapse was observed in 47.4% ( n = 28) of the patients, with a median time to relapse of 6.0 (4.0–7.5) months. Relapsed patients had an earlier onset of CSU than non‐relapsed [11.9 (8.0–13.9) and 14.1 (11.5–15.9) years, p = .028]. The pre‐treatment symptom duration was significantly longer in relapsed patients than in non‐relapsed patients [21.0 (8.0–36.0) and 8.0 (6.0–21.0) months, p = .010]. Patients with symptoms longer than 7.5 months prior to starting omalizumab had a higher risk of relapse (AUC: 0.695, 95% CI: 0.561–0.830; p = .010; sensitivity: 82.1%, specificity: 45.2%). Pretreatment symptom duration was identified as a significant risk factor, increasing the likelihood of relapse (OR: 1.134, 95% CI: 1.011–1.272, p = .032). No significant differences were found between relapsed and non‐relapsed patients in terms of other clinical and laboratory factors. Late relapse was more common in ANA‐positive patients than early relapse [14 (87.5%) vs. 2 (12.5%), p = .021]. Conclusion Delayed initiation of omalizumab treatment following the onset of urticaria symptoms is associated with an increased risk of relapse. Therefore, omalizumab treatment should be initiated promptly in eligible patients.