Anaphylactic reactions associated with omalizumab administration: Analysis of a case-control study

An ELISA was designed to distinguish between bound and unbound omalizumab by IgE (Bureco AG) to account for the high affinity of omalizumab for the Fc fragment of human IgE. Because of omalizumab's mechanism of action, its effect on blunting skin test reactivity, and interference with the assay to detect ATAs against omalizumab, serum sample collections for the repository database were conducted at least 16 weeks after discontinuation of omalizumab to allow for washout of the drug. Characteristic Cases of anaphylaxis(n = 30) Controls(n = 88) Mean ± SD age at time of event (y)[low *] 42.7 ± 16.4 45.4 ± 15.4 Sex: female, n (%) 27 (90.0) 60 (68.2) Race, n (%) White 26 (86.7) 62 (70.5) Black 1 (3.3) 10 (11.4) Asian 0 2 (2.3) Other 3 (10.0) 14 (15.9) Geographic region, n (%) West 10 (33.3) 33 (37.5) Midwest 7 (23.3) 19 (21.6) Northeast 6 (20.0) 12 (13.6) South 7 (23.3) 24 (27.3) Mean ± SD preomalizumab IgE (IU/mL)[dagger] 317.9 ± 416.0 455.5 ± 758.5 Mean ± SD best FEV1 (%)[double dagger] 79.3 ± 15.9 82.9 ± 15.9 History of anaphylaxis or anaphylactoid episode, n (%) 17 (56.7) 20 (22.7) Mean ± SD age at asthma diagnosis (y) 23.7 ± 19.5 20.2 ± 17.4 Omalizumab frequency, n (%) Every 2 wk 16 (53.3) 40 (45.5) Every 4 wk 13 (43.3) 40 (45.5) Mean ± SD total no. of omalizumab doses§ 18.6 ± 19.6 58.5 ± 59.7 History of allergies/allergic rhinitis, n (%) 29 (96.7) 86 (97.7) History of food allergies, n (%) 18 (60.0) 33 (37.5) History of allergic reaction following any injection, n (%) 10 (33.3) 18 (20.5) Table I Demographic and baseline characteristics