Exhaled NO (ENO) has been studied as a noninvasive marker of airway inflammation, and has been shown to be elevated in asthma patients. The aim of this study was to investigate whether ENO measurements differ significantly between groups of asthmatic children with different disease control and to compare ENO measurements with the clinical assessment of asthma control. Seventy-three children between 5-18 years old with a diagnosis of asthma were recruited. ENO was measured online during a slow vital capacity maneuver. The mean of three plateau NO levels was used for analysis. Baseline and postbronchodilator spirometry were performed. The assessment of disease control was based on the frequency of use of beta2-agonists, occurrence of day- and nighttime asthma symptoms, and spirometry results. Twenty-one children (group 1) had good asthma control. In 31 patients (group 2), asthma control was acceptable. In 21 patients (group 3), asthma was insufficiently controlled. ENO levels were (median (quartiles)): group 1, 11 ppb (9-21); group 2, 15 ppb (11-26); and group 3, 28 ppb (19-33). Measurements were significantly different between all three groups (P = 0.009, Kruskal-Wallis), between groups 1 and 3 (P = 0.01, Mann-Whitney U test), and between groups 2 and 3 (P = 0.01, Mann-Whitney-U test). The same was true for reversibility testing. We found significantly different ENO levels between a group of pediatric asthma patients with insufficient and good/sufficient control, as defined by clinical assessment. These results suggest that ENO measurements may be useful for monitoring asthma patients.
Copyright 2003 Wiley-Liss, Inc.