Comment: The quality of evidence is downgraded by study limitations (unclear allocation concealment, selective reporting, and high or unknown participant attrition in around half of the studies).
A Cochrane review included 52 studies with a total of 5077 subjects. Most participants had mild or intermittent asthma, often with co-morbid allergic rhinitis. Eighteen studies recruited only adults, 25 recruited only children and several recruited both or did not specify. A general trend suggested sublingual immunotherapy (SLIT) benefit over placebo, but variation in scales meant that results were difficult to interpret. Changes in inhaled corticosteroid use in micrograms per day (MD 35.10 mcg/d, 95% CI -50.21 to 120.42; low-quality evidence), exacerbations requiring oral steroids (studies = 2; no events) and bronchial provocation (SMD 0.69, 95% CI -0.04 to 1.43; very low-quality evidence) were not often reported. Serious adverse events were infrequent, and analysis using risk differences suggests that no more than 1 in 100 are likely to suffer a serious adverse event as a result of treatment with SLIT (RD 0.0012, 95% CI -0.0077 to 0.0102; 22 studies, n=2560; moderate-quality evidence). More people taking SLIT had adverse events of any kind compared with control (OR 1.70, 95% CI 1.21 to 2.38; 19 studies, n=1755, low-quality evidence), but events were usually reported to be transient and mild.
Date of latest search: 25 March 2015