Author: Salma MA. Musaad

Publisher:

Published: 2007

Total Pages: 113

ISBN-13:

Pediatric studies of associations among obesity, asthma and allergic sensitization are inconclusive. Body mass index (BMI) is commonly used to classify study participants as obese. BMI, however, does not reflect central fat distribution, a known risk factor for metabolic disorders. This research tested the hypothesis that central fat distribution increases risk for asthma and allergic sensitization, measured using the skin prick test for aeroallergens. Measures of central fat distribution included waist circumference, waist to height ratio (WHtR) and conicity index. Childhood studies rarely utilize these alternative measures for characterizing the relationship between obesity and asthma or allergic sensitization. In this study, alternative measures of obesity were compared with BMI percentiles; the association between obesity and asthma in children with allergic rhinitis was investigated; the association between obesity and allergic sensitization in children with and without asthma, rhinitis and eczema was explored. To account for the effects of several obesity measures on the above outcomes, a structural equation model was developed. Results show that BMI percentiles are discordant with 18-46% of children classified as obese using the alternative measures. A high WHtR or conicity index increases likelihood for asthma in children with allergic rhinitis. Prevalence of a high WHtR consistently increases from allergic rhinitis to mild asthma to moderate/severe asthma. Sensitization to aeroallergens appears to protect against an asthma diagnosis (OR=0.6; 95% CI=0.4-0.9), but is positively associated with rhinitis (OR=8.1; 95% CI=4.9-13.5) and eczema (OR=1.9; 95% CI=1.0-3.4). In children with rhinitis, those with a moderate WHtR are twice as likely to have increasing positive skin prick tests (OR=1.9; 95% CI=1.1-3.3) compared to low WHtR. In children with asthma, obesity appears to protect against increasing positive skin prick tests per BMI percentiles (OR=0.5; 95% CI=0.3-0.9) or waist circumference (OR=0.3; 95% CI=0.1-0.9). This finding suggests that the pathway for asthma is different in children with central obesity. Alternative measures that better account for fat distribution are superior to BMI percentiles for characterizing the relationship between childhood obesity with asthma and with allergic sensitization in the context of asthma, rhinitis and eczema.