Shortened immunotherapy dose-escalation saves time, but is it safe? A case-control study comparing the rates of adverse reactions between conventional and fast-escalation subcutaneous immunotherapy protocols during the induction phase.

Abstract

BACKGROUND: Allergen immunotherapy (AIT) is the only intervention believed to change the course of atopic diseases. As dogs appear to have fewer severe adverse events (AEs) compared to people receiving AIT, a prolonged dose-escalation induction phase might not be needed. OBJECTIVES: To report the incidence and characteristics of AEs induced by a fast-escalation subcutaneous immunotherapy (f-SCIT) protocol compared to a conventional (c-SCIT) regimen. ANIMALS: One hundred dogs treated with either f- SCIT (Centre 1, 50 dogs) or c-SCIT (Centre 2, 50 dogs). METHODS AND MATERIALS: A case-control study retrospectively evaluating AEs during the induction of AIT. We determined the incidence and type of AEs in each SCIT group; we also assessed factors such as self-limitation and the need for AE-associated protocol changes. RESULTS: Twelve of 100 dogs (12%) developed a SCIT-attributable AE during the induction phase, with one dog having a local and 11 having systemic reactions (nine Grade I, two Grade II, none of grades III or IV). Dogs treated with the f-SCIT had a significantly higher rate of AEs (11 of 50; 22%) compared to those receiving the c-SCIT (one of 50; 2%). Most of the AEs (10 of 11; 91%) in the f-SCIT group were mild and self-limiting. CONCLUSIONS AND CLINICAL IMPORTANCE: The induction phase of f-SCIT is simpler, and the maintenance phase is reached faster than that of the c-SCIT. Despite its higher rate of AEs than with the c-SCIT regimen, the majority of f-SCIT-associated AEs were mild and self-limiting. Whether or not this f-SCIT protocol leads to a faster time-to-efficacy needs to be determined.