Long-term efficacy of allergen immunotherapy: what do we expect?

Allergen-specific immunotherapy (SIT) is the only treatment of allergic diseases able to maintain its efficacy after discontinuation of treatment. The available literature suggests that a 3-year duration of treatment maintains the efficacy on allergic symptoms for at least an equivalent period of time. The current paper compares the 3- and 5-year duration in children with dust mite-induced asthma, and confirms that 3 years of SIT maintains its effectiveness for a further 3 years after stopping, with no significant difference compared with 5 years. Thus, 3 years is likely to be an adequate duration of SIT; however, studies with more prolonged follow-up periods are needed to investigate the persistence of the clinical benefit over time.