Serum levels of specific IgE to cow's milk and its components as predictors of anaphylaxis in Chinese children with cow's milk allergy.

BACKGROUND

Cow's milk allergy (CMA) is one of the most common food allergies in young children. As improved diagnostic tools, allergic tests are inconsistent and limited in predicting anaphylaxis.

OBJECTIVE

To explore risk factors for anaphylaxis and to determine practical cut-offs for allergic tests in predicting anaphylaxis.

METHODS

This is a prospective cohort study. Children with IgE-mediated CMA were enrolled and divided into three groups (Group 1: non-anaphylaxis; Group 2: GRADE I anaphylaxis; Group 3: GRADE II-IV anaphylaxis that warranted epinephrine). Prick-to-prick tests (PTPs) using fresh cow's milk (CM) were performed. Serum specific IgE (sIgE) against CM and its components, including casein, alpha-lactalbumin, beta-lactoglobulin, and bovine serum albumin were measured. The 90% and 95% positive predictive value (PPV) decision points for predicting anaphylaxis were determined. Potential predictors of anaphylaxis were evaluated in logistic regression models.

RESULTS

This study included 134 CMA patients with a median age of 14.4 months. The sensitization rate to any CM component was 89%. Group 3 was more likely to be sensitized to multiple CM components and have higher sIgE levels. The 95% PPV diagnostic decision points of casein-sIgE in predicting anaphylaxis was 13.0 kUA/L. For GRADE II-IV anaphylaxis, casein-sIgE ≥ 54.9 kUA/L could provide a PPV of 88.9%. The elevated casein-sIgE level (OR 14.0, P=0.025) and complicating respiratory allergic diseases (OR 4.8, P=0.022) were independent risk factors for GRADE II-IV anaphylaxis.

CONCLUSION

High casein-sIgE levels are strongly associated with CM anaphylaxis. Detection of casein-sIgE may offer an additional value for the prediction of CM anaphylaxis.