Exhaled nitric oxide helps discriminating asthmatic children with and without positive specific IgE to aeroallergens.

Abstract

Aeroallergen sensitization may predict higher fractional exhaled nitric oxide (FeNO) levels. We evaluate cut-off values of FeNO in asthmatic children with and without positive specific immunoglobulin E (IgE) to at least one of 5 aeroallergens (Dermatophagoides pteronyssinus, Dermatophagoides farinae, cat, dog, and cockroach). 564 patients with asthma and allergic rhinitis (AR) aged 5 to 18 years were enrolled into two groups. Sensitized group included 378 children with positive IgE to at least one of 5 inhaled allergens. Non-sensitized group included 186 children. Pulmonary function tests, FeNO, eosinophil counts, and IgE levels were examined. Patients were divided into preschool age (5~6 years old), elementary school children (7~11 years old) and adolescents (12~18 years old). In preschool children, FeNO≥15.5 ppb differentiates between non-sensitized and sensitized groups. (sensitivity 54.3%; specificity 87.5%; positive predictive value (PPV) 86.2%; negative predictive value (NPV) 57.1%; area under receiver operating characteristic curve (AUC) 0.72) Among elementary school children, the cut-off value of FeNO≥19.5 ppb showed sensitivity 66.4%; specificity 85.8%; PPV 90.5%; NPV 55.7%; AUC 0.81. In adolescents, FeNO≥27.5 ppb showed sensitivity 60.2%; specificity 85.4%; PPV 91.2%; NPV 46.1%; AUC 0.76. In asthmatic children, aeroallergen sensitization appears to contribute to higher FeNO levels than those not sensitized. Cut-off values of FeNO which well discriminate asthmatic children with and without aeroallergen sensitization should be chose according to different ages.