Airway inflammatory and spirometric measurements in obese children.
OBJECTIVE
To investigate the association between obesity and airway inflammation and spirometric parameters in local children.


METHODS
Cross-sectional and observational study.


METHODS
Paediatric clinics of a university-affiliated teaching hospital in Hong Kong.


METHODS
Chinese subjects aged 6 to 18 years were recruited from the paediatric clinics. Obesity was defined as being 120% or more of the median weight-for-height.


METHODS
Airway inflammation assessed by exhaled nitric oxide concentration; lung function evaluated by measuring forced expiratory flow in 1-second and forced vital capacity using spirometry; and peak expiratory flow rate measured by using a mini-Wright peak flow meter.


RESULTS
Fifty-five subjects were recruited into four groups as follows: 13 non-obese controls, 16 obese non-asthmatics, 15 non-obese asthmatics, and 11 obese asthmatics. The median (interquartile range) exhaled nitric oxide concentrations of these groups were 17.6 (14.4-20.9), 33.3 (26.1-75.4), 65.7 (32.0-110.0) and 49.2 (41.1-82.6) parts per billion, respectively (P=0.001 for trend). Post-hoc analysis revealed higher exhaled nitric oxide concentration in the latter three groups (obese and/or asthmatic subjects) than controls (P< or =0.002). Exhaled nitric oxide concentration did not differ among obese non-asthmatics, non-obese asthmatics, and obese asthmatics (P>0.1 for all). In non-asthmatics, exhaled nitric oxide concentration correlated positively with age (P=0.048), weight-for-height z-score (P=0.001), and forced vital capacity (P=0.009). Weight-for-height z-score correlated positively with forced vital capacity (P=0.041), but inversely with the forced expiratory flow in 1-second/forced vital capacity ratio (P=0.049). Such correlations were not observed in asthmatic children.


CONCLUSIONS
Increased airway inflammation as revealed by exhaled nitric oxide concentration was found in obese non-asthmatic children. Weight-for-height z-score as an indicator of childhood obesity correlated with exhaled nitric oxide concentration and spirometric parameters in children without asthma. Nonetheless, concomitant obesity does not influence exhaled nitric oxide concentration in asthmatic children. Further studies are needed to identify the pathophysiologic mechanisms for such associations.
The Chinese University of Hong Kong, Prince of Wales Hospital, Shatin, Hong Kong.
Joyce S W
JS
Chow
Amelia S M
AS
Leung
Wincy W S
WW
Li
Teresa P K
TP
Tse
H Y
HY
Sy
T F
TF
Leung
D000293:Adolescent; D001249:Asthma / Q000150:complications* / Q000503:physiopathology; D001944:Breath Tests / Q000379:methods; D002648:Child; D003430:Cross-Sectional Studies; D005541:Forced Expiratory Volume; D006723:Hong Kong; D006785:Hospitals, University; D006801:Humans; D066298:In Vitro Techniques; D007249:Inflammation / Q000175:diagnosis / Q000209:etiology* / Q000503:physiopathology; D008297:Male; D009569:Nitric Oxide / Q000032:analysis; D009765:Obesity / Q000150:complications*; D010366:Peak Expiratory Flow Rate; D013147:Spirometry; D014797:Vital Capacity
D009569:Nitric Oxide