Non-invasive markers of airway inflammation as predictors of oral steroid responsiveness in asthma.
BACKGROUND
Sputum eosinophil counts and exhaled nitric oxide (NO) levels are increased in asthma and both measurements fall in response to corticosteroids.


METHODS
Exhaled NO levels and sputum eosinophil counts were assessed as non-invasive markers of the response to an oral steroid in 37 patients (19 women) with stable chronic asthma (mean (SD) age 48.6 (12.2) years, asthma duration 25. 9 (17.3) years, and baseline forced expiratory volume in one second (FEV(1)) 76.3 (21.9)% predicted). Spirometric tests, with reversibility to a beta agonist (2.5 mg nebulised salbutamol), and induced sputum (using nebulised 3% saline) were performed at recruitment and following treatment with 30 mg prednisolone/day for 14 days.


RESULTS
Baseline NO levels correlated with the percentage improvement in FEV(1) from baseline to the post-steroid, post-bronchodilator value (r(s) = 0.47, p = 0.003), with an NO level of >10 ppb at baseline having a positive predictive value of 83% for an improvement in FEV(1) of > or =15% (sensitivity 59%, specificity 90%). Sputum eosinophilia (> or =4%) had a positive predictive value of 68% (sensitivity 54%, specificity 76%) for an increase in FEV(1) of > or =15%. A combination of sputum eosinophilia and increased NO levels resulted in a positive predictive value of 72% and a negative predictive value of 79% (sensitivity 76%, specificity 75%).


CONCLUSIONS
Exhaled NO levels and sputum eosinophilia may be useful in predicting the response to a trial of oral steroid in asthma.
Little
S A
SA
Department of Respiratory Medicine, Western Infirmary, Glasgow G11 6NT, UK.
Chalmers
G W
GW
MacLeod
K J
KJ
McSharry
C
C
Thomson
N C
NC
D000280:Administration, Inhalation; D000284:Administration, Oral; D000328:Adult; D000420:Albuterol / Q000627:therapeutic use*; D000893:Anti-Inflammatory Agents / Q000627:therapeutic use*; D001249:Asthma / Q000188:drug therapy* / Q000378:metabolism; D001944:Breath Tests; D004804:Eosinophils / Q000187:drug effects*; D005260:Female; D005541:Forced Expiratory Volume; D006801:Humans; D007958:Leukocyte Count / Q000187:drug effects; D008297:Male; D008875:Middle Aged; D009569:Nitric Oxide / Q000032:analysis*; D011239:Prednisolone / Q000627:therapeutic use*; D011446:Prospective Studies; D013183:Sputum / Q000187:drug effects
D000893:Anti-Inflammatory Agents; D009569:Nitric Oxide; D011239:Prednisolone; D000420:Albuterol