Association of subcutaneous allergen-specific immunotherapy with incidence of autoimmune disease, ischemic heart disease, and mortality

BackgroundSubcutaneous allergen-specific immunotherapy (SCIT) is a well-documented treatment of IgE-mediated allergic disease. Little is known about potential effects of SCIT on the risk of other chronic immune-related diseases. Over the years, a few casuistic reports have caused concern that SCIT might act as a trigger of autoimmune disease.ObjectiveWe aimed to investigate the association of SCIT with the incidence of autoimmune disease and ischemic heart disease (IHD), as well as all-cause mortality.MethodsAll Danish citizens without other known diseases were linked and followed through central registries on medications and hospital admissions. Persons receiving SCIT and persons receiving conventional allergy treatment (CAT; nasal steroids or oral antihistamines) were compared with regard to mortality and development of autoimmune diseases, acute myocardial infarction (AMI), and IHD. Cox regression (survival analysis) with age as the underlying time scale was used to estimate relative risks (hazard ratios [HRs] with 95% CIs) associated with SCIT compared with CAT adjusted for age, sex, vocational status, and income.ResultsDuring the 10-year study period (1997-2006), a total of 18,841 and 428,484 persons were followed in the SCIT and CAT groups, respectively. Receiving SCIT was associated with lower mortality (HR, 0.71; 95% CI, 0.62-0.81) and lower incidence of AMI (HR, 0.70; 95% CI, 0.52-0.93), IHD (HR, 0.88; 95% CI, 0.73-1.05), and autoimmune disease (HR, 0.86; 95% CI, 0.74-0.99).ConclusionIn this registry-based observational study, receiving SCIT compared with CAT was associated with lower risk of autoimmune disease and AMI, as well as decreased all-cause mortality.