PURPOSE OF THE STUDY.
To determine whether exhaled nitric oxide (eNO), lung function, airway reactivity, allergen sensitization, and cytokines measured during infancy are predictors of asthma at age 5 years.
The study participants included 116 infants and toddlers with eczema. The median age was 10.7 months (range 2.6–19.1 months). Participants were enrolled before the development of wheezing illness. There were 90 study participants, the majority of whom were white, at follow-up (5 years of age), and 68% had a diagnosis of asthma.
In this longitudinal study of a US cohort, measures were obtained during infancy and repeated at follow-up at age 5 years. eNO was measured in ppb. A raised volume technique was used to obtain forced expiratory flow in infants. Airway reactivity was measured using methacholine challenge. Total immunoglobulin (Ig)E and specific IgE to egg white, milk, wheat, house dust mite, grass, tree, ragweed, Alternaria, and Th1 and Th2 cytokines levels were obtained.
Infants and toddlers who developed asthma had eNO levels 3.5 ppb (95% confidence interval [CI] 0.12–6.84 ppb; P = .035) higher at baseline compared with those without asthma at 5 years of age. This trend in higher eNO persisted at age 5, those with asthma had higher eNO levels 10.8 ppb (95% CI 1.53–19.99; P = .023) compared with those without asthma. Higher eNO in infancy correlated with greater odds of asthma at age 5; for each 1 ppb increase in eNO, there was 1.13 (95% CI 1.01–1.26; P = .037) greater odds of asthma. Higher eNO in infancy correlated with airway hyperreactivity at age 5; for each 1 ppb increase in eNO, forced expiratory volume in 1 second decreased by 0.76% (95% CI 0.71%–0.85%; P = .015) during methacholine challenge at age 5. Additionally, egg sensitization (>0.35 IU/mL) in infancy correlated with asthma at age 5 (P = .02).
In this longitudinal study, elevated eNO in infant and toddlers with eczema was a predictor of asthma and airway hyperreactivity at age 5.
There is a paucity of studies that have examined the use of eNO during infancy as a predictor of asthma later in life. More longitudinal studies are needed to investigate this relationship further because predictors of asthma development are not well established. Longitudinal studies with repeat measures at different time points in infancy through midchildhood are needed to better characterize the association between eNO and asthma development. Moreover, this study should be replicated in a large diverse population including low-income and minority children who are disproportionately affected by asthma (Akinbami LJ et al. NHCS Data Brief No. 94, May 2012; http://www.cdc.gov/nchs/data/databriefs/db94.pdf). The findings from this study suggest that eNO may have clinical utility as a predictor of asthma in high-risk infants.
- Copyright © 2015 by the American Academy of Pediatrics