An Update On: The Observed Incidence of Anaphylaxis in Patients Receiving Omalizumab in a Tertiary Allergy and Asthma Clinic in Canada

RATIONALE: In a post-marketing analysis last updated in July 2007, the FDA reported an estimated 0.2% of patients suffered treatment related anaphylaxis and rare incidence of serum sickness. To substantiate this rate, we assessed the occurrence of treatment related anaphylaxis and serum sickness in our large Canadian allergy and asthma tertiary clinic.

METHODS: We performed a retrospective chart review of our entire database of omalizumab administration in patients between 2005 and 2017.

RESULTS: The FDA defined treatment related anaphylaxis as the development of bronchospasm, hypotension, syncope, urticaria, chest tightness, generalized pruritus, and/or angioedema post injection. They reported 51% of anaphylactic incidents occurred between 0 – 60 minutes of injection, 8% occurred between 60 – 120 minutes of injection and 41% occurred more than 120 minutes of injection.
During our post market experience, between 2005 and 2017, our clinic administered 49,776 injections of omalizumab to 434 patients (147 males & 287 females) over the course of 1498 patient-years and no cases of anaphylaxis or serum sickness like symptoms were observed.

CONCLUSIONS: Meticulous care is taken by our omalizumab administration clinic to ensure optimal safety based on the emphasized warnings of anaphylaxis and indicated warnings and precautions for serum sickness. Data collected in this analysis observed no cases of anaphylaxis or serum sickness like symptoms in the treatment of 434 patients who received a combined total of 49,776 injections of omalizumab. Thus, healthcare professionals should have more confidence in treating patients with omalizumab based on the rare occurrence of anaphylaxis and serum sickness.