464 Specific Venom Ige Decrease during 5 Years of Venom Immunotherapy (VIT): Clinical Relevance in Stung and Not Stung Patients

BACKGROUND: As the question of how long VIT should last in order to provide long-term protection is a long-standing issue, we evaluated the specific venom IgE decrease throughout 5-years-long VIT in 3 groups of yellow jacket (YJ) venom-allergic patients: stung during the first 3 years of VIT (SP3), during the last 2 years (SP5) and patients not stung (NS). METHODS: We retrospectively evaluated 232 patients submitted to 5-year-long VIT. Specific venom IgE levels were determined at the baseline, after 3 and 5 years of VIT (CAP method, Phadia, Italy). All stung patients were clinically protected. ANOVA analysis evaluated differences among CAPs and in each CAP value among the 3 groups. MANOVA multivariate analysis evaluated differences in overall CAPs and the effects of age, gender, Mueller grade and stings number. A P < 0.05 was considered statistically significant. Data were analysed by ‘SPSS’ 13.0 (SPSS Inc., Chicago, IL). We called NS patients to check if they were stung after VIT discontinuation. RESULTS: We selected 84 NS, 72 SP3 and 76 SP5 patients. Specific YJ-IgE levels decreased during VIT, as CAPs are statistically different at time 0, 3 and 5 (P < 0.001). Considering CAP levels at the first control (CAP3), NS patients presented lower values than SP3 patients (P = 0.002); no significant difference was found between NS and SP5 patients. At the last control (CAP5), CAP values of NS and SP5 patients were different (P = 0.002) as well as between SP3 and SP5 patients (P = 0.014). No significant difference was found between NS and SP3 patients. By MANOVA, IgE decrease was inversely correlated with Mueller grade (P = 0.012) and age (P = 0.002). We recalled all NS patients by phone, 7/84 (8.3%) patients related one well tolerated sting, as they did not develop any allergic reaction. CONCLUSIONS: In everyday practice if a patient never stung during VIT fulfils the temporal criterion, but specific IgE are not negative, a decrease of IgE levels ranging from 57 to 70% in respect to baseline might be a satisfactory parameter for stopping VIT. As a further confirmation of our conclusions, even if not statistically significant, all not stung patients were clinically protected after VIT discontinuation.