The relationship of exhaled nitric oxide to airway inflammation and responsiveness in children

Exhaled nitric oxide (eNO) is a potential tool in epidemiological studies of asthma. It was hypothesized that in a cross-sectional survey of asthma in adolescent children, eNO may contribute to the detection of this disease. A cohort of Australian school children in two educational years (n = 107, aged 14.7 +/- 2.3 years, 42.9% female) were surveyed in terms of exhaled nitric oxide (eNO), which was compared with other indicators of asthma: asthma symptoms, atopy [skin prick tests (SPT)], hypertonic saline bronchial reactivity, sputum inflammatory cells and eosinophilic cationic protein. Significant positive correlations were found with eNO and number of positive skin prick tests (p = 0.001; n = 98), symptoms (p = 0.05; n = 107), sputum eosinophils (p = 0.025; n = 83), and sputum eosinophilic cationic protein (p = 0.009; n = 83). There was no significant relationship with airway hyperresponsiveness (p = 0.3; n = 15). eNO had a negative predictive value for asthma of 83%, and a positive predictive value of 54%, which is comparable with most current tests for diagnosing asthma. eNO appears to be a useful indicator of atopy and airway inflammation, but in this population it was not closely related to airway hyperresponsiveness.