What is the tolerance age of patients with cow's milk protein allergy? What are the parameters that can predict its persistence?

Objective: Cow’s milk allergy (CMA) is one of the most common food allergies in infants. The natural history of CMA indicates that resolution is common. Some studies suggest that food allergies are now being resolved at an older age. The aim of this study was to investigate the tolerance and persistence characteristics, as well as the timing of tolerance, in our own CMA patients. Material and Methods: Patients who were diagnosed with CMA and followed up in our pediatric immunology and allergy outpatient clinic between 2016-2021 years were evaluated retrospectively. Patients’ demographic characteristics, laboratory results, and tolerance time were recorded. Results: The 632 patients’ files were reviewed. 192 (30%) of the patients were followed for more than two years. The tolerance to baked products was observed with a median of 14 months, while the tolerance to fermented products was observed with a median of 17 months. Full tolerance was observed with a median of 25 months. The number of patients older than 2 years of age who could not consume any milk protein-containing product was 72 (11.4%) and 56 (77.7%) of them were IgE mediated CMA. The rate of girls with tolerance (43.5%) was found to be significantly higher than nontolerant girls (25%) (p=0.001). The mean skin test diameter of the tolerant group was significantly higher than the mean of the non-tolerant group (p=0.022). The percentage of eosinophils (p=0.003) and total IgE level (p=0.004) in the tolerant group were significantly lower compared to the intolerant group. There was no significant difference between the presence of tolerance in terms of allergy number, eosinophil count and specific IgE count (p>0.05). Conclusion: Identifying the factors influencing tolerance can lead to changes in the management of the disease. We observed that 88.6% of patients older than 2 years were tolerant to milk proteins, and all patients with non-IgE mediated CMA achieved tolerance by 2 years of age. The ratio of total IgE to specific IgE, age, total IgE and specific IgE levels, presence of non-IgE or IgE mediated allergy, and gender were factors that influenced the development of tolerance in our study. Age at diagnosis and having a single or multiple food allergies did not impact the tolerance status. The prognosis for CMA remains favorable. The use of the milk ladder in managing CMA is an important approach for promoting early tolerance.