Exhaled nitric oxide: a predictor of steroid response.
BACKGROUND
The initial management of patients who present with persistent respiratory symptoms includes recognizing those with the potential to benefit from inhaled steroid therapy. To date, this has required undertaking a "trial of steroid" to identify responders. There is increasing evidence that steroid response is more likely in patients with eosinophilic airway inflammation, and this can be assessed indirectly using exhaled nitric oxide (FENO) measurements.


OBJECTIVE
We aimed to assess the predictive accuracy of FENO to identify steroid response in 52 patients presenting with undiagnosed respiratory symptoms in a single-blind, fixed-sequence, placebo-controlled trial of inhaled fluticasone for 4 weeks.


METHODS
Comparisons of predictive accuracy were made between FENO and other conventional predictors: peak flows, spirometry, bronchodilator response, and airway hyperresponsiveness measured at baseline. "Steroid response" was defined as change in symptoms, peak flows, spirometry, or airway hyperresponsiveness to adenosine based on established guidelines and recommendations.


RESULTS
Steroid response was significantly greater in the highest FENO tertile (> 47 ppb) for each endpoint. This outcome was independent of the diagnostic label. The predictive values for FENO were significantly greater than for almost all other baseline predictors, with an optimum cut point of 47 ppb.


CONCLUSIONS
FENO measurements greater than 47 ppb provide a means of predicting steroid response in patients with undiagnosed respiratory symptoms. Assessing airway inflammation is of more practical value than diagnostic labeling when considering the potential usefulness of inhaled antiinflammatory therapy.
Smith
Andrew D
AD
Otago Respiratory Research Unit, Dunedin School of Medicine, University of Otago Medical School, Dunedin, New Zealand.
Cowan
Jan O
JO
Brassett
Karen P
KP
Filsell
Sue
S
McLachlan
Chris
C
Monti-Sheehan
Gabrielle
G
Peter Herbison
G
G
Robin Taylor
D
D
D000280:Administration, Inhalation; D000328:Adult; D000730:Androstadienes / Q000008:administration & dosage; D000893:Anti-Inflammatory Agents / Q000008:administration & dosage; D001249:Asthma / Q000175:diagnosis / Q000188:drug therapy*; D005260:Female; D000068298:Fluticasone; D006801:Humans; D008297:Male; D009569:Nitric Oxide / Q000032:analysis*; D011237:Predictive Value of Tests; D012372:ROC Curve; D012680:Sensitivity and Specificity; D016037:Single-Blind Method
D000730:Androstadienes; D000893:Anti-Inflammatory Agents; D009569:Nitric Oxide; D000068298:Fluticasone