Association between the Asthma Predictive Index and levels of exhaled nitric oxide in infants and toddlers with recurrent wheezing

It is difficult to make an early identification of which children with recurrent wheezing will develop asthma in the following years. The Asthma Predictive Index (API) is a questionnaire based on clinical and laboratory parameters used for this end. The measurement of fractional exhaled nitric oxide (FE NO) has been used as a marker of eosinophilic airway infammation in asthma patients. Objective. To determine the association between the Asthma Predictive Index and FE NO levels in children younger than 3 years old with recurrent wheezing. Materials and methods. Observational, cross sectional study. Children younger than 36 months old with 3 or more episodes of bronchial obstruction in the past year who were inhaled corticosteroid-naive or leukotriene receptor antagonist-naive were included. After recording clinical data, FE NO was measured by a chemiluminescence analyzer during tidal breathing (online method). Results. A total of 52 children aged 5-36 months old were included. Patients with a positive API accounted for 60% of the population and had higher levels of FE NO than those with a negative API, with a median (range) of 13.5 ppb (0.7-31) versus 5.6 ppb (0.1-20.8), respectively (p <0.01). A high FE NO (>8 ppb) was observed in 74% of children with a positive API and in 26% of those with a negative API (p <0.01). Conclusions. This study found an association between high levels of exhaled nitric oxide and a positive Asthma Predictive Index in children younger than 3 years old with recurrent wheezing.