Between-occasion repeatability of fractional exhaled nitric oxide measurements in children

The aim of the study was to assess short-term repeatability of measurements of fractional exhaled nitric oxide (F(E)NO) and its correlates in children in the 6- to 9-year age bracket participating in a respiratory epidemiological survey. F(E)NO was measured in two sessions one week apart in 101 children. Participants were divided into three groups: asymptomatic (n = 76); symptomatic (n = 14); and asthma (n = 11). Absolute and relative differences between the measurements, as well as concordance correlation coefficients, were used in order to assess repeatability. The two F(E)NO measurements were strongly correlated (0.98). Although intragroup comparisons of the two measurements were not significantly different (p = 0.2), intergroup comparisons were. F(E)NO measurements are reproducible in children in epidemiological settings.