Supplementary Material for: Predictors of Persistent Milk Allergy in Children: A Retrospective Cohort Study

<b><i>Background:</i></b> Cow’s milk (CM) allergy is the second most common food allergy developed during infancy in Japan. To identify predictors of persistent CM allergy, we investigated the tolerance acquisition rate based on an oral food challenge in children under 6 years of age, diagnosed with immediate-type CM allergy. <b><i>Methods:</i></b> This retrospective cohort study included 131 children born in 2005 with a history of immediate allergic reaction to CM, of whom 39 were excluded because of ongoing oral immunotherapy (<i>n</i> = 18) or a lack of follow-up data (<i>n</i> = 21). The 92 remaining participants were followed for 6 years. Tolerance was defined as no adverse reaction to 200 mL of CM and regular intake of milk at home. Subjects were divided into 3 groups based on age at tolerance acquisition: group I (<3 years; <i>n</i> = 31), group II (3–6 years; <i>n</i> = 42), and group III (persistent allergic group; <i>n</i> = 19). <b><i>Results:</i></b> Tolerance acquisition rates by 3, 5, and 6 years of age were 32.6% (30/92), 64.1% (59/92), and 84.8% (70/92), respectively. Age at first hospital visit was significantly higher in groups II and III than in group I (<i>p</i> < 0.001). The incidence of anaphylaxis to other foods was also higher in group III than in group I (<i>p</i> = 0.04), as was CM-induced anaphylaxis (<i>p</i> = 0.03). Furthermore, milk and casein-specific immunoglobulin E (IgE) levels were significantly higher in group III than in group II after birth and remained high thereafter (<i>p</i> < 0.05). <b><i>Conclusions:</i></b> The history of anaphylaxis and high milk-specific IgE levels were associated with persistent CM allergy.