Cow's milk oral immunotherapy in real-life: up to 15-year follow-up study

Background. Oral immunotherapy (OIT) is a promising strategy for severe and persistent cow's milk (CM) allergy. However, clinical experience concerning long-term follow-up is scarce. The objective is to assess long-term efficacy and safety of maintenance phase of OIT in real-life. Methods. Prospective study of children with severe IgE-mediated CM allergy that underwent CM-OIT, and were followed-up by the authors, up to 15 years. Complete desensitisation was defined when maintenance dose of 200 mL daily was achieved. Characterization (clinical and laboratory) was performed before and after OIT during follow-up.  Results. Thirty-three patients enrolled: 58% male, 70% asthmatics and 67% with previous history of CM-anaphylaxis. Mean age at onset of CM-OIT was 7±2.8 years. Complete desensitisation was ensured in 94% (free diet with dairy 200mL of CM or equivalent). During maintenance phase 79% developed allergic reactions, with anaphylaxis in 33%, including exercise-induced anaphylaxis in 15% and with cheese intake in 15%. We stress that eosinophilic esophagitis appeared in 12%. Specific IgE levels and skin prick tests (SPT) to CM and casein have significantly decreased, and in most patients (61%) SPT became negative. When available, specific IgG4 levels have significantly increased. Conclusions. This real-life study supports long-term efficacy and safety of CM-OIT. CM-OIT had a high success rate, allowing diet without restrictions with persistence of the effect up to 15 years. However, one-third of patients experienced anaphylaxis during maintenance phase. CM-OIT should always be performed by allergy experts and only motivated families should be enrolled, since long-term follow-up is required, and daily intake of CM is needed to ensure desensitization.