Prevention of new sensitizations in monosensitized subjects submitted to specific immunotherapy or not.  A retrospective study. 
Specific immunotherapy is the only currently available allergen-orientated treatment able to modify the natural history of respiratory allergic diseases.  Safety and clinical efficacy of this treatment are well documented, but evidence about the ability to reduce new sensitizations is still poor.  We report a retrospective study conducted in order to assess the prevention of new sensitizations in monosensitized subjects treated with specific immunotherapy vs. monosensitized patients treated with anti-allergic drugs.  8396 monosensitized patients with respiratory symptoms were selected according to an open, retrospective design.  Group A included 7182 patients submitted to specific immunotherapy (and anti-allergic drugs when needed) for 4 years and then treated with drugs for at least 3 years.  Group B included 1214 patients treated only with drugs for at least 7 years.  All patients underwent prick test with a standard panel of allergens and total and specific IgE determination before and after 4 years of treatment and again 3 years later.  Groups were well balanced.  Polysensitized subjects were 23.75% in Group A and 68.03% in Group B after 4 years (P < 0.0001) and 26.95% and 76.77%, respectively, after 7 years (P < 0.0001).  Asthmatic subjects were more prone to develop polysensitization in comparison to subjects suffering only from rhinitis (32.14% instead of 27.29% after 4 years, 36.5% instead of 31.33% after 7 years; P < 0.0001).  Specific IgE decreased by 24.11% in Group A and increased by 23.87% in Group B (P < 0.0001).  Total IgE decreased by 17.53% in Group A and increased by 13.71% in Group B (P < 0.0001).  Specific immunotherapy was observed retrospectively to reduce new sensitizations in monosensitized subjects suffering from respiratory allergic diseases.