Young Infants with Recurrent Wheezing and Positive Asthma Predictive Index Have Higher Levels of Exhaled Nitric Oxide

Abstract

Objective. The aim of this post hoc analysis was to establish the relationship between FE_NO levels and the asthma predictive index (API) among infants with recurrent wheezing. Methods. Infants with recurrent wheezing (three or more episodes) were recruited consecutively and online FE_NO tests at tidal breathing with multiple breaths were performed. Results. Twenty-seven (84%) out of 32 infants (median age of 12 months) who met the inclusion criteria for this post hoc analysis, successfully performed the FE_NO determinations. Eighteen (66%) infants were classified with positive stringent API. FE_NO levels were significantly higher among patients with positive API than those with negative (median [IQR] of 12.3 [14.8] ppb vs. 4.1 [7.9] ppb, respectively, p = .016). Furthermore, FE_NO and positive API had a significant correlation (Spearman’s rho, ρ = 0.4741, p = .0125). After logistic regression analysis including FE_NO levels, gender, age, and use of controller therapy, FE_NO was the only variable that was marginally related to API (OR = 1.12, 95% CI: 0.99–1.27, p = .07). Conclusion. Infants with recurrent wheezing who had a positive stringent API already had higher FE_NO levels than those with a negative API. This finding needs to be corroborated in a larger prospective study.

• asthma predictive index
• early childhood asthma
• fraction of exhaled nitric oxide
• infants
• recurrent wheezing

Acknowledgments

The authors thank Dr Mark A. Brown (from the Pediatric Pulmonary Section, Arizona Respiratory Center, University of Arizona) for his editorial assistance.