Long-lasting effect of a monophosphoryl lipid-adjuvanted immunotherapy to parietaria. A controlled field study.

BACKGROUND The clinical efficacy of Monophosphoryl lipid A-adjuvanted immunotherapy (MPLA-SCIT) is ascertained, but there are no data on its possible long-lasting effect. We assessed in a real-life setting the persistence of the clinical effect five years after discontinuation. METHODS Patients with parietaria-induced respiratory allergy and fulfilling the criteria for immunotherapy prescription were evaluated at baseline, after the third year of MPLA-SCIT and five years after discontinuation. Visual analog scores, severity of the disease, pulmonary function and skin reactivity were assessed. Matched subjects who refused immunotherapy served as controls. RESULTS Twenty nine patients received MPLA-SCIT and 28 were the control group. There was a significant clinical improvement, as assessed by VAS only in the active group after 3 years that remained significant at 5 years versus baseline and controls. The distribution of severity of rhinitis was overall decreased at 3 and 8years as well. The number of patients with conjunctivitis in the active group decreased from 19 to 6 at the end of the treatment and to 9 after 5 years. There was also a decrease in the number of patients with asthma symptoms (from 6 to 2 to 4), which doubled in the control group. A significant reduction in the wheal of the Parietaria skin test was seen in the active group at the end of the treatment (9.5 +/- 2.1 mm vs. 6.4 +/- 2.6 mm; p = .01), but this reduction was lost at the 5-year. No relevant change was overall detected in pulmonary function. CONCLUSION MPLA-SCIT is effective, and the clinical efficacy is maintained after 5 years of discontinuation.