Association between obesity and asthma in 4-11 year old children in the UK

Background-There is evidence of a positive association between asthma and o besity in adults and in children. We investigated, in a large sample of Eng lish and Scottish primary school children, whether there is a consistent as sociation between fatness and asthma symptoms in Britain. Methods-A cross sectional analysis was made of 18 218 children aged 4-11 ye ars who participated in the 1993 or 1994 surveys of the National Study of H ealth and Growth (NSHG). Children belonged either to English or Scottish re presentative samples, or an English inner city sample. Asthma attacks in th e previous year, occasional wheeze, or persistent wheeze were the symptoms used in the analysis. Body mass index (BMI) and the sum of triceps and subs capular skinfolds converted to standard deviation scores (SDS) were used to assess levels of fatness. Results-A total of 14 908 children (81.8%) were included in the analysis. I n the multiple logistic analysis BMI and asthma (asthma attacks or wheeze) were associated in the representative sample (OR for the comparison of the 10th and 90th centiles of BMI 1.28, 95% CI 1.11 to 1.48), but sum of skinfo lds was unrelated to asthma symptoms in most analyses. The association betw een asthma and BMI was stronger in girls than in boys in the inner city sam ple, but less convincingly in the representative sample. Conclusions-Levels of obesity are associated with asthma symptoms regardles s of ethnicity. The association is more consistent for BMI than for sum of skinfolds, partly because obese children are more advanced in their maturat ion than other children. There is some evidence that, as in adults, the ass ociation is stronger in girls than in boys, but only in the multiethnic inn er city sample.