Tolerance of a cluster schedule on the treatment of seasonal allergic respiratory disease with pollen extracts quantified in mass units.

In order to evaluate the tolerance of a cluster schedule on specific immunotherapy (SIT), 306 patients were included in a multicenter study. The patients were suffering from rhinoconjunctivitis with/without asthma, caused by sensitization to olive and/or grass pollen. SIT was administered subcutaneously according to a cluster schedule in which the maintenance dose is reached after four visits (3 weeks). The extracts were biologically standardized with major allergens quantified in mass units. Local reactions appeared in 7.2% of the patients and 1.3% of the doses. Systemic reactions (SR) were recorded in 1.2% of the doses administered to 9.5% of the patients. No anaphylactic shock was registered, and all the SR responded fully and rapidly to treatment. There was no difference in SR according to diagnosis or allergen extract used. The majority of SR occurred with the administration of vial of higher concentration (Vial 2: 7 SR (22%), Vial 3: 32 SR (78%), p < 0.05). Of the 32 SR recorded with Vial 3, 13 (41%) were immediate, with no existing association between dose administered and appearance of SR. However, of the 18 delayed SR (56%), 14 occurred after the administration of the first two doses of Vial 3 and four occurred after administration of the second two doses (78% vs 22%, p < 0.05). On the other hand, this regime realized an important saving in cost and time compared to the conventional schedule (1581 fewer doses and 2754 fewer visits were necessary to reach the optimal dose). Considering all these factors, the clinical profile of the proposed regime may be qualified as good. However, future studies are necessary in order to better adjust the schedule to avoid the delayed SR that occurred after the administration of the first two doses of Vial 3.