Recommendations for appropriate sublingual immunotherapy clinical trials

Sublingual immunotherapy is currently considered a viable alternative to the subcutaneous route. The body of evidence of its efficacy is based on the results of 77 clinical trials and 7 meta-analyses, that have been published so far. Nonetheless, the experimental evidence is partially weak due to the large heterogeneity of studies, namely: doses, regimens, patient selection, duration of treatment, outcomes and reporting. In addition, it is virtually impossible to compare the potency of extracts produced by different manufacturers. Also, there is large variability in reporting and in the classification of adverse events, either systemic or local, so that only a rough estimate can be provided. Considering all these aspects, efforts are needed to harmonize the methodology, outcome measures and reporting of SLIT clinical trials, to achieve the ability of comparing the results of various studies. International societies and the World Allergy Organization have recently provided general recommendations on how to design and conduct trials which can provide more interpretable and homogeneous data.