Available online 15 September 2022

Chronic Spontaneous Urticaria (CSU) not controlled by optimized doses of antihistamines is referred to as refractory CSU. Add-on therapies recommended by guidelines include omalizumab, immunosuppressive and anti-inflammatory agents.

Objectives: The objective of the study was to assess the real-world effectiveness of different add-on treatment options for refractory CSU in two large clinical practices.

A retrospective chart review was conducted in 264 patients with refractory CSU not adequately controlled for <b>≥</b>6 weeks with optimized doses of second-generation histamine-1 blockers. Omalizumab and hydroxychloroquine were the most frequently prescribed add-on therapies, allowing comparisons of clinical outcomes for these two agents. Complete response included absent or infrequent urticaria and patient satisfaction with treatment. Partial response was reduced hives, but requiring a second add-on therapy. Sustained response was complete response to an add-on therapy for ≥1 year.

Omalizumab add-on treatment was significantly more likely to be associated with a complete response vs hydroxychloroquine. Complete sustained response at 1 year was observed in 82% (111/134) of patients on omalizumab and 66% (73/111) on hydroxychloroquine as the first add-on therapy (p<0.01). Patients with thyroid disease had a poorer response to add-on treatments (45 % responded versus 63 %; P=0.03). In patients with incomplete responses to first add-on interventions (n=45), 65% and 62% subsequently had complete responses to omalizumab and hydroxychloroquine, respectively.

Although omalizumab was superior, hydroxychloroquine achieved a complete response in two-thirds of treated patients. Given a favorable safety profile, hydroxychloroquine should be considered as an add-on treatment for refractory CSU.

© 2022 Published by Elsevier Inc. on behalf of the American Academy of Allergy, Asthma & Immunology