Immunotherapy safety: what have we learned from surveillance surveys?

Subcutaneous allergen immunotherapy (SCIT) is beneficial for the treatment of allergic rhinitis, asthma, and in preventing stinging insect anaphylaxis, but is not without risks. Four retrospective surveillance surveys and one on-going national prospective study have attempted to characterize the incidence and risk factors for fatal and non-fatal SCIT reactions. These studies have contributed significantly to currently recommended SCIT safety guidelines. Recent surveillance studies indicate stable SR rates, and a possible decline in the incidence of fatal reactions since the implementation of evidence-based safety guidelines. This review will provide a detailed summary of the evidence from surveillance studies for risk factors associated with SCIT reactions, including: uncontrolled asthma, prior systemic reactions, dosing during peak pollen seasons, epinephrine being delayed or not given, dosing or administration errors, inadequate waiting times, reactions occurring more than 30 min after injections, injections given in medically unsupervised settings, concomitant beta-blocker and angiotensin-converting enzyme inhibitor (ACEi) use, and accelerated build-up regimens.