Young infants with recurrent wheezing and positive asthma predictive index have higher levels of exhaled nitric oxide.

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.