Role of sublingual immunotherapy in the treatment of asthma: An updated systematic review

Background: The purpose of the systematic review is to evaluate the efficacy and safety of sublingual immunotherapy (SLIT) for the treatment of allergic asthma. Methods: PubMed, Embase, and CENTRAL databases were searched, updating an earlier review (January 1, 2005 through May 8, 2017). Randomized, controlled studies (RCTs) were included, which reported one of the prespecified outcomes: asthma symptoms measured by control composite scores; quality of life; medication use; pulmonary physiology; and health-care utilization. For safety outcomes, RCTs and observational studies were included. Two independent reviewers extracted data, assessed risk of bias, and graded strength of evidence (SOE) for each outcome. Results: Fourteen RCTs (n = 2585) assessed the efficacy of SLIT for asthma. The RCTs utilized house dust mite (HDM), birch, or grass allergen. SLIT improved asthma symptoms (high SOE), decreased use of long-term control medication, and improved forced expiratory volume in 1 second (FEV ₁ ) (moderate SOE). SLIT may decrease quick-relief medication use, and improve disease-specific quality of life (low SOE). For safety, 20 RCTs and 10 observational studies (n = 3621) were identified. Local (risk differences ranged from −0.03 to +0.765) and systemic allergic reactions (risk differences ranged from −0.03 to +0.06) were a common occurrence in SLIT and control groups. Life-threatening reactions were uncommon, with 3 cases of anaphylaxis and no deaths reported. Conclusion: There is moderate-to-high strength evidence that SLIT improves allergic asthma symptoms, reduces long-term control medication use, and improves FEV ₁ based on studies of HDM, birch, and grass. SLIT rarely is associated with life-threatening adverse events.