Predictors for failed dose reduction of inhaled corticosteroids in childhood asthma.

BACKGROUND AND 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.

Standard reference for the six-minute-walk test in healthy children aged 7 to 16 years.

RATIONALE: We have previously reported that the six-minute-walk test (6MWT) is a reliable and valid functional test for assessing exercise tolerance and endurance. There is a lack of pediatric standard reference for the 6MWT. OBJECTIVES: To construct height-specific standards for the 6MWT for children aged 7 to 16 years. METHODS: The anthropometric data, spirometric lung function, and six-minute-walk distance (6MWD) of Chinese children aged 7 to 16 years were prospectively measured using standardized protocols. The findings were used to construct height-specific standards for the 6MWT. The least mean square (LMS) method using maximum penalized likelihood was used to facilitate model fitting. Factors significantly associated with 6MWD were also determined. MEASUREMENTS AND MAIN RESULTS: From January 2005 to April 2006, a total of 1,445 subjects were studied. The measured variables showed a normal distribution. Height-specific reference standards for 6MWT were constructed for both male and female children. Forward stepwise multiple regression analysis revealed height and difference in heart rate before and after the walk test to be important clinical variables associated with 6MWD. CONCLUSIONS: These 6MWD standards will provide useful references for the care of pediatric patients.

Sputum induction in children with asthma: a tertiary-center experience.

Our aims were 1) to report on our experience with sputum induction (SI), and 2) to determine predictive factors associated with successful SI in asthmatic children. Children with asthma attending the chest clinic of a university teaching hospital between October 2003-December 2004 were recruited. They completed a visual analogue scale for symptom severity, and underwent physical examination, skin-prick test, exhaled nitric oxide (eNO) measurement, spirometry, and SI. Adequate sputum contained <50% squamous epithelial cells. Predictors for successful induction were evaluated using multivariate logistic regression analysis. One hundred and thirty subjects were recruited. The median age was 11.25 years (range 7.0-17.5), and the majority were boys (75%). All except two had normal percent predicted forced expired volume in 1 sec (>80%). The median eNO was 48.95 ppb. Sputum induction was successful in 93 subjects (74.5%). Sore throat and chest discomfort occurred in 20 (15%) and 8 (6%) subjects, respectively, and the procedure was prematurely terminated in three cases. Levels of eNO were found to be a predictor for successful induction (area under the ROC (receiver operator characteristics curves) curve, 0.634). Sputum induction was well-tolerated by all subjects, and was successful in 74.5% of cases. Exhaled nitric oxide may be a useful marker for successful induction.

Once-daily fluticasone propionate in stable asthma: study on airway inflammation.

Children with stable asthma receiving twice-daily fluticasone propionate (FP) were studied. Spirometry, exhaled nitric oxide (eNO) and sputum eosinophils were measured at baseline and 8 weeks after FP was changed to once-daily use while keeping the same total dosage. Visual analogue scores on asthma severity, symptoms, and dosing regimen preference were obtained. Twenty-nine children of mean age 10.6 years (SD 2.5) were recruited. There was significant improvement in eNO (47.1 ppb [30.3] vs. 39.9 ppb [27.1], p = 0.037), and sputum eosinophils (5.7% [6.5] vs. 2.5% [3.9], p = 0.024] after 8 weeks. All subjects preferred the once-daily dosing regimen. Once-daily FP is effective in controlling airway inflammation. This frequency of medication use is also the preferred regimen.

Bronchodilator effect of salbutamol from two different spacer devices.

Our aim was to compare the bronchodilator effect of salbutamol delivered via a new holding chamber (Volumatic Soft, VS) with that of an established device (Volumatic, V) in asthmatic children. Children with stable asthma were recruited. They inhaled 100 microg, and 10 min later, 300 microg of salbutamol aerosol delivered via VS or V on day 1, and vice versa on day 2. Spirometry was measured at baseline, 10 min after 100 microg, and 15 min after 300 microg of salbutamol were given. The preference for either device was assessed by visual analogue score. Forty-four children with a median age of 9.2 years (interquartile range, 8.0-10.7) completed the study. There were significant improvements in forced expired volume in 1 sec (FEV1) with time throughout the study period for both V and VS (linear and quadratic trend P < 0.001). There was a statistically significant difference in postbronchodilator FEV1 between V and VS (P = 0.013). VS gave an overall greater change in FEV1 than V, by 1.8%. The preference scores for V and VS were 7.0 (IQR 5.0-8.0) and 9.0 (IQR 8.0-10.0) (p < 0.0005), respectively. In conclusion, comparable clinical efficacy was found for V and VS with respect to changes in FEV1 after salbutamol. Patients also showed a strong preference for the new device.