In a real-world trial, although the monoclonal antibody Omalizumab was better, Hydroxychloroquine attained a full response in two-thirds of treated chronic spontaneous urticaria (CSU) patients. Najeeb Khan et al. sought to evaluate the efficacy of several add-on therapy options for CSU.

In 264 people with CSU who had not been successfully treated for ≥six weeks with optimal dosages of 2nd generation histamine-1 blockers, a retrospective chart review was conducted. The two drugs that were most often given as add-on therapy were Omalizumab and Hydroxychloroquine, permitting comparisons of their clinical results. Patient satisfaction with the therapy and absent or rare urticaria were all signs of a complete response. Decreased hives were a partial response, but a 2nd add-on medication was still necessary.

The sustained response was defined as a complete response following an add-on therapy for ≥ one year. Compared to Hydroxychloroquine, Omalizumab add-on therapy dramatically increased the probability of a complete response. Notably, 111 out of 134 subjects (82%) receiving Omalizumab and 73 out of 111 patients (66%) receiving Hydroxychloroquine as the initial add-on treatment experienced a complete sustained response at the 1-year.

Add-on therapies were less effective for patients with thyroid disease (45% vs. 63% responders). Patients (n = 45) who had only partially responded to the initial add-on therapies later had complete responses to Omalizumab (65%) and Hydroxychloroquine (62%) respectively. Due to Hydroxychloroquine's high responder rate and reduced cost, it appears to be an acceptable alternative to Omalizumab for CSU management.