METHODS: We reviewed the charts of every patient who underwent rapid induction of aeroallergen immunotherapy at our institution. Extracts were dosed per practice parameters. All patients were pretreated for three days with prednisone, an H1 antagonist, and an H2 antagonist; some also received montelukast. Patients achieved an average dose of 10% maintenance on the day of rapid induction. We calculated the rate of reactions occurring on the day of induction and of the subsequent day. We classified reactions using the WAO systemic reaction scale.
RESULTS: 110 patients underwent 149 rapid induction procedures from July 2011 through July 2017. The rate of systemic reactions on the day of induction was 23% (35/149), and, 74% of the time, the reaction severity was WAO grade 2 (range 1-2). 83% (29/35) of patients with systemic reactions received medications; 67% (23/35) received epinephrine. All patients were discharged directly from clinic; none required hospitalization. The rate of systemic reaction for the subsequent injection was 5% (8/149); average WAO grade 2 (range 1-2). Pretreatment with montelukast was associated with decreased likelihood of systemic reaction independent of other risk factors.
CONCLUSIONS: Rapid induction of immunotherapy carries a significant risk of anaphylaxis, even when the target dose is 10% of the maintenance dose. Use of montelukast was associated with decreased likelihood of systemic reaction.