Fractional exhaled nitric oxide has a good correlation with asthma control and lung function in latino children with asthma.

Background: Although the measurement of fractional exhaled nitric oxide (FE(NO)) has been recommended for observational studies and clinical trials of asthma, FE(NO) has not been examined in studies of childhood asthma in Latin America,

Objective: To examine the relationship between FE(NO) and indicators of disease control or severity [asthma control test/childhood asthma control test (ACT/C-ACT), lung function, and exercise challenge test (ECT)] in Mexican children with persistent asthma,

Methods: Children (6-18 years of age) with persistent asthma were consecutively recruited in a tertiary asthma clinic and divided into two groups, e.g. FE(NO) < 20 parts per billion (ppb) and ≥20 ppb.Adequate FE(NO) measurements were obtained in 134 (83.2%) of 161 eligible children,

Results: Children with FE(NO)<20 ppb had significantly higher scores on the ACT/C-ACT than those with FE(NO) ≥ 20 ppb (median [interquartile range] :23 [20.8-25] vs. 21 [18-24], p = .002, respectively). Compared to children with FE(NO) ≥20 ppb, those with FE(NO) <20 ppb had a higher baseline predicted forced expiratory volume (FEV(1)) [94% (92.5%-99.4%) vs. 83% (81%-89.9%), p = .001] and a lower probability of having a positive ECT (42.7% vs. 71.2%, p = .001). In addition, FE(NO) was significantly inversely correlated with the participants' ACT/C-ACT score and predicted FEV1, and directly correlated with positive ECT, CONCLUSION: Among Mexican children with persistent asthma, low levels of FE(NO) ( <20 ppb) are associated with better asthma control, and higher lung function.