Predictors for failed dose reduction of inhaled corticosteroids in childhood asthma.
OBJECTIVE
Studies of Western populations have shown that increased exhaled nitric oxide (FeNO) and/or sputum eosinophils (sp-Eos) are predictive of asthma exacerbations. However, the utility of these measurements in different populations and settings is unknown. This study aimed to determine the predictors for failure of reduction of inhaled corticosteroid (ICS) doses in children with stable asthma.


METHODS
Fifty children (median age 11.8 years, interquartile range (IQR) 5.9 years) had their dose of ICS halved every 8 weeks until they reached the study end-point (exacerbation or weaned off ICS). Spirometry, FeNO and induced sputum cells were measured at baseline and at each stage of ICS reduction.


RESULTS
Eleven subjects suffered an asthma exacerbation and the remainder was successfully weaned off ICS. Subjects with an exacerbation were older (15.4 years (IQR 5.4) vs 11.4 years (IQR 3.9), P = 0.019) and more likely to be boys (P = 0.035). FeNO (median 156 p.p.b. (IQR 131) vs 76.1 p.p.b. (IQR 79.5), P = 0.013) and sp-Eos (17.3% (IQR 33.8%) vs 7.1% (IQR 9.9%), P = 0.019) were significantly greater in those who had an exacerbation. The areas under the receiver operating characteristic curves for FeNO (0.78, 95% CI: 0.59-0.97, P = 0.013) and sp-Eos (0.76, 95% CI: 0.56-0.96, P = 0.016) were similar (P = 0.88) and both were significantly greater than that for FEV(1)% predicted (0.12, 95% CI: 0.08-0.56, P = 0.0013).


CONCLUSIONS
Older boys with raised FeNO and sp-Eos are at higher risk of failure of reduction in their ICS dose. Monitoring airway inflammation in children with asthma using FeNO or sp-Eos is clinically useful in guiding ICS dose reduction in a non-Western outpatient setting.
Li
Albert M
AM
Department of Paediatrics, Prince of Wales Hospital, The Chinese University of Hong Kong, Shatin, Hong Kong, China. albertmli@cuhk.edu.hk
Tsang
Tony W T
TW
Lam
Hugh S
HS
Sung
Rita Y T
RY
Chang
Anne B
AB
D000280:Administration, Inhalation; D000293:Adolescent; D000305:Adrenal Cortex Hormones / Q000008:administration & dosage / Q000627:therapeutic use*; D001249:Asthma / Q000188:drug therapy* / Q000378:metabolism / Q000473:pathology; D001944:Breath Tests; D002648:Child; D002681:China; D015331:Cohort Studies; D004305:Dose-Response Relationship, Drug; D004804:Eosinophils / Q000473:pathology*; D005260:Female; D006801:Humans; D008297:Male; D009569:Nitric Oxide / Q000378:metabolism*; D011014:Pneumonia / Q000208:ethnology / Q000378:metabolism / Q000473:pathology; D011237:Predictive Value of Tests; D011446:Prospective Studies; D012720:Severity of Illness Index; D013147:Spirometry; D013183:Sputum / Q000166:cytology*
D000305:Adrenal Cortex Hormones; D009569:Nitric Oxide