Real-Life Adherence to Venom Immunotherapy and Adrenaline Autoinjector

Introduction: Venom immunotherapy (VIT) and adrenaline autoinjector (AAI) are important therapies in venom anaphylaxis. Adherence to VIT and AAI in patients with venom allergy has been evaluated in a few studies; however, solid data are lacking. This study aimed to evaluate VIT and AAI retrieval rates in patients with venom allergy with a special focus on adherence to treatment. Adherence was compared to subcutaneous immunotherapy (SCIT) with inhalant allergens. Methods: This was a retrospective study among patients registered for allergen immunotherapy at the Allergy Center, Odense University Hospital, Denmark, from January 1, 2010, to December 31, 2014. Data on purchased immunotherapy and AAI were obtained from the Danish National Health Service Prescription Database. Multivariable logistic regression was used to analyze if allergen, age, sex, mastocytosis, and treatment site affected adherence. Results: The 3-year adherence to VIT was 92.4% (244/264) compared to 87.4% (215/246) in SCIT with inhalant allergens, and the 5-year adherence to VIT was 84.1% (222/264) compared to 74.8% (184/246) in SCIT with inhalant allergens (p = 0.045). Females treated with VIT were more adherent than males (p = 0.45 [3-year], p = 0.008 [5-year]), whereas allergen, age, mastocytosis, or treatment site did not significantly affect adherence. Only 28.6% of patients (12/42) purchased an AAI after premature termination of VIT. Conclusion: In this register-based study, we found that the 3- and 5-year adherences to VIT and SCIT with inhalant allergens are at the upper end of the spectrum hitherto reported. Patients' 5-year adherence to VIT was higher than patients' 5-year adherence to SCIT with inhalant allergens. If VIT was prematurely terminated, less than 1/3 would have purchased an AAI.