Specific immunotherapy in asthma: a comprehensive review

Abstract

Background: The prescription of allergen immunotherapy (SIT) in asthma remains a matter of debate and official guidelines often do not provide clear recommendations in this regard. Methods: An extensive review of the literature was untaken. Results: There are many robust studies with SCIT and SLIT showing positive results related to improving asthma symptoms, in particular when asthma was associated with rhinitis. In addition, there are several favourable meta-analyses, although their validity is limited by the heterogeneity of the trials included. The disease modifying effect of SIT (prevention of asthma onset and long-lasting effects) should be considered when prescribing this treatment. Regarding safety, fatalities seem to be rare: in Europe no fatality has been reported over the last two decades, and the same has been observed in USA in the last 4 years. Uncontrolled asthma is universally recognized as the most important risk factor for severe adverse events, but there is no clear demonstration that SIT can worsen or induce asthma. In contrast, of the few studies specifically designed to evaluate asthma, none had a formal sample size calculation, and pulmonary function was assessed as primary outcome only sporadically. Conclusions: According to the presently available evidence, SLIT and SCIT can be used in asthma associated with rhinitis (the most common condition), provided that asthma is adequately controlled by pharmacotherapy. In such cases, a measurable clinical benefit on asthma symptoms can be expected. SIT cannot be presently recommended as single therapy when asthma is the unique manifestation of respiratory allergy.