Immunotherapy safety: a prospective multi-centric monitoring study of biologically standardized therapeutic vaccines for allergic diseases.

Background: The fear of side-effects has led to strict regulations preventing a more widespread use of specific immunotherapy (SIT) in some countries, in spite of the low risk of systemic reactions (SRs) reported in well-controlled studies. The goal of the study was to carry out a prospective and multi-centric trial to evaluate the safety, risk factors and compliance degree of commercially available SIT.

Materials And Methods: The study was carried out in 14 allergy departments from Spain. Four-hundred and eighty-eight patients with rhinitis and/or asthma were submitted to treatment with biologically standardized allergen extracts commercially available. They were administered following the European Academy of Allergy and Clinical Immunology guidelines.

Results: Four hundred and twenty-three patients (86.7%) completed the treatment and remained under control at the end of the trial. Out of 17,526 administered doses, 17,368 doses (99.1%) were not associated with a reaction. Eighteen patients (3.7%) experienced 53 (0.3% of the doses) SRs. All immediate SRs were mild or moderate and responded well to ordinary treatment measures. There were no fatal reactions, anaphylactic shock or life-threatening reactions. A higher ratio of SRs was found among asthmatic and dust mite allergic patients, although multi-variable logistic analysis did not demonstrate any risk factor associated with SRs. There was also a subgroup of patients at risk for recurrent reactions, and therefore 40% of SRs had been avoided if the maximal number of SRs had been previously limited to only three SRs.

Conclusions: This multi-centric study showed that SIT was a safe treatment with a very good compliance. Future guidelines of SIT should limit the maximal number of SRs.