Risk factors and management of systemic reactions induced by subcutaneous immunotherapy

Abstract

To explore the risk factors (causes or possible causes) of systemic reactions induced by subcutaneous immunotherapy (SCIT) through clinical observations and develop countermeasures for preventing further SCIT-induced systemic reactions. Each patient on SCIT at our department from December 1993 to September 2013 was inquired about systemic reactions induced by SCIT. Individuals with systemic reactions immediately after SCIT were included. Clinical history and manifestations were inquired and recorded carefully. Risk factors of systemic reactions were probed and analyzed. SCIT schedule was adjusted according to the risk factors and the patients on continuous SCIT were followed up until the end of SCIT course. A total of 70 reactions were observed in 35 patients during the observation period. A large majority (97.1% (68/70) ) of systemic reactions occurred at a maximal concentration of 10(-2). Risk factor included an injection of maximal dosage (0.6-1.0 ml of 10(-2) vial, 27.2% (28/103) ), a further injection of large dosage (0.1-0.5 ml of 10(-2) vial) during pollen season (20.4% (21/103) ), incremental dose regardless of marked local reaction (12.6% (13/103) ), suspected incorrect injection procedure(12.6% (13/103) ) and an injection with a wrong vial of higher concentration (9.7% (10/103) ). Countermeasures were taken accordingly, include stopping injection of maximal dosage, avoiding SCIT of 10(-2) vial on pollen season, decreasing SCIT dosage on existence of large local reactions, performing SCIT only at medical institutions capable of managing anaphylaxis and implementing normalized injection procedures. Most patients (n = 29) finished the course of SCIT successfully without further systemic reactions. Six patients ceased SCIT for personal reasons or on medical advice. Probing the risk factors of systemic reactions induced by SCIT and adopting countermeasures accordingly prevent further systemic reactions. It may provide rationales for preventing or minimizing systemic reactions during SCIT.