Oral food challenge test to confirm the diagnosis of cow's milk allergy.

Objective: To determine the prevalence of cow's milk protein allergy in children with symptoms attributed to cow's milk intake.

Methods: Sixty-five children with symptoms attributed to cow's milk intake were studied. Diagnosis was established after an open oral food challenge test carried out at least 15 days after an elimination diet and absence of symptoms, with a follow-up period of up to 4 weeks after the test. The children who remained asymptomatic after this period were considered negative for cow's milk protein allergy (n = 30), while those whose symptoms reappeared were considered positive (n = 35).

Results: The median age was 5 months (P 25-75% 2-9 months) in the case group and 7 months (P 25-75% 4-11 months) in the comparison group (p = 0.05). The test did not confirm cow's milk protein allergy in 46.8% of the patients with symptoms attributed to cow's milk intake. A delayed reaction occurred in 77.1% (27/35) of the cases testing positive, 18/27 in the first week, 3/27 in the second week, and 6/27 in the third week of follow-up. A statistically significant association was found between cutaneous manifestations and positive test result (p = 0.04). However, there was no association with digestive and respiratory symptoms.

Conclusion: Our results confirm the need of an oral food challenge test to determine which patients really have cow's milk protein allergy and may therefore benefit from a diet free of cow's milk.