Exhaled nitric oxide reflects asthma severity and asthma control.
BACKGROUND
This study was undertaken to a) evaluate whether exhaled nitric oxide (fraction of exhaled nitric oxide [FENO]) levels are reflective of asthma severity in concordance with the National Asthma Education and Prevention Program categorization and b) determine the usefulness of FENO using the single-breath exhalation technique for monitoring asthma control and compliance with steroid treatment.


METHODS
Thirty patients with asthma (7-17 yrs old; 14 males and 16 females) that was mild (n=8), moderate (n=17), or severe (n=5) were included in the study. Fifteen patients were seen on more than one occasion for a total of 53 visits. Information obtained at each visit included asthma symptoms, beta-agonists and corticosteroids use, compliance to steroids, and forced expiratory volume in 1 sec (FEV1) and FENO measurements. Asthma control was judged by a pulmonologist based on overall evaluation of symptoms, FEV1 measurements, and the frequency of beta-agonists use at each visit.


RESULTS
The mean +/- SD FENO was significantly different in the mild, moderate, and severe asthma categories (30 +/- 12, 65 +/- 48, 104 +/- 68, respectively; F(2,52)=6.02 p=.005). FENO was significantly correlated with asthma severity (r=.44, p=.001), compliance (r=-.75, p=.001), and control (r=-.51, p=.001). There were no statistically significant differences between asthma severity and compliance or FEV1.


CONCLUSIONS
Our data suggest that a) FENO may be a practical tool to evaluate asthma severity and asthma control over time and b) FENO may be used as a marker of compliance with steroids even when FEV1 has not decreased significantly.
Delgado-Corcoran
Claudia
C
University of Florida Health Sciences Center at Jacksonville, Jacksonville, FL, USA.
Kissoon
Niranjan
N
Murphy
Suzanne P
SP
Duckworth
Laurie J
LJ
D000293:Adolescent; D000704:Analysis of Variance; D018927:Anti-Asthmatic Agents / Q000627:therapeutic use; D001249:Asthma / Q000175:diagnosis* / Q000188:drug therapy; D001944:Breath Tests; D002648:Child; D016903:Drug Monitoring; D005260:Female; D006801:Humans; D008297:Male; D009569:Nitric Oxide / Q000378:metabolism*; D010349:Patient Compliance; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D012720:Severity of Illness Index
D018927:Anti-Asthmatic Agents; D009569:Nitric Oxide