A pilot study on the application of a symptom-based score for the diagnosis of cow’s milk protein allergy

OBJECTIVE A challenge is the recommended test to diagnose cow's milk protein allergy. However, many parents and physicians prefer to not challenge because the procedure may cause (severe) symptoms. In clinical routine, diagnostic testing is only available for IgE-mediated allergy. The aim of this study was to test the diagnostic accuracy of a symptom-based score to select infants at risk of having cow's milk protein allergy. METHODS A symptom-based score was developed and consensus was reached that a score of ≥12 would select infants at risk of cow's milk protein allergy. Diagnosis of cow's milk protein allergy was demonstrated with a positive challenge after 1-month elimination diet. RESULTS An open challenge was performed in 85/116 (73%) infants suspected of cow's milk protein allergy based on a symptom-based score ≥ 12 and was positive in 59/85 (69%). Although "a challenge test" was planned in the protocol, 27% of the parents refused the challenge. The mean decrease after 1 month of elimination diet with an extensive hydrolysate was -8.07 (95% confidence interval = -8.74, -7.40). If the symptom-based score during the elimination diet decreased to 6 or lower, 80% of the infants had a positive challenge test. If the symptom-based score remained >7, the challenge test was positive in only 48% (p < 0.001). CONCLUSION In daily practice, a symptom-based score of ≥12 is a useful tool to select infants at risk of cow's milk protein allergy. If an elimination diet reduces the symptom-based score to ≤6, the challenge test is positive in 80%.