Assessing the safety of subcutaneous immunotherapy dose adjustments

Background: Subcutaneous immunotherapy injections are often dose adjusted owing to late injections, for newly mixed vials after refills, or after systemic reactions (SRs) to reduce the subsequent SR risk. This practice is not strongly evidence based.

Objectives: To analyze the safety of the Wilford Hall Medical Center dose-adjustment schedule.

Methods: A retrospective cohort analysis of a standardized dose-adjustment schedule across 4 years and covering 12,895 injections was performed to analyze the SR rate immediately after dose adjustments for late reactions (1 dose for each week late starting after 2 weeks), for newly mixed vials (a 50% dose reduction), or after a SR (a 10-fold dilution).

Results: Male patients (odds ratio [OR], 1.15; P <. 005), pediatric patients (OR, 1.19; P <. 01), and maintenance stage injections (OR, 2.14; P <.001) required more dose adjustments for late injections. Maintenance stage injections also experienced more dose adjustments for newly mixed vials (OR, 10.78; P <. 001). Pediatric patients (OR, 2.15; P <. 002) and buildup stage injections (OR, 2.38; P <. 005) were associated with an increased SR frequency and, as a result, required more post-SR dose adjustments. In each scenario, following the dose-adjustment schedule included in this article did not cause an increase in subsequent SRs.

Conclusions: Multiple unique characteristics were found to be associated with the requirement for subcutaneous immunotherapy dose adjustment, and this sample dose-adjustment protocol was not associated with an increased risk of a subsequent SR. The safety of this proposed dose-adjustment protocol should be confirmed in future prospective studies.