Long-Term Clinical Effect Of Grass-Allergen Immunotherapy In Local Allergic Rhinitis, And Its Capacity to Modify The Natural Course Of The Disease.

Several randomized double-blind placebo-controlled trials have demonstrated the beneficial clinical effect of allergen immunotherapy (AIT) in improving symptoms, medication requirements and quality of life of local allergic rhinitis (LAR) patients. This study intends to investigate two new aspects: 1: the long-term clinical effect of AIT after its discontinuation; 2: the capacity of AIT to prevent asthma onset in LAR patients. Objective 1: two-year prospective study of 19 LAR individuals who satisfactorily responded to three-year treatment with grass-AIT. Objective 2: comparative study of the previous individuals (AIT group) and LAR patients not receiving AIT (not-AIT). An assessment of the clinical state, asthma presence, use of rescue medication, visits to the emergency department, quality of life (RQLQ), and a nasal allergen provocation test (NAPT) were performed at baseline (the moment of AIT discontinuation in the treated group) and two years later. Two years after AIT discontinuation, 94.7% of patients in the AIT group maintained a similar/better clinical state, 89.5% showed a similar/lesser consumption of rescue medication, 73.7% reported a similar/better RQLQ (P>0.05), and there was an increase in the concentration of allergen tolerated in the NAPT. During the study period, 25% of not-AIT patients required visits to emergency department and 11.9% developed asthma, whereas no visit or asthma cases occurred in the AIT group (P<0.001). Three years of grass-AIT induces a long-term clinical effect on LAR, which persists after therapy discontinuation, and prevents asthma. This effect might be related to the achievement of immunological tolerance.