OBJECTIVE:
Prevalence rates for both overweight and asthma have been increasing among
children in developed countries over the last two decades. Some recent
studies have postulated a causal relationship between these but have lacked
power to form a definitive conclusion. The objective of this study was to
estimate the effect of high body weight in childhood on the future risk of
asthma.
METHODS:
MEDLINE search (1966 to October 2004), supplemented by manual search of
reference lists and gray literature. We included cohort studies that
examined high body weight at birth or during childhood and future outcome of
asthma. We extracted data from each study on exposure status, clinical
outcome and study characteristics.
RESULTS:
We initially identified 402 studies, of which 12 met our inclusion criteria.
The combined results from four studies that examined the effect of high body
weight during middle childhood on the outcome of subsequent asthma showed a
50 percent increase in relative risk (RR 1.5, 95% confidence interval [CI],
1.2, 1.8)). The combined results from nine studies that examined the effect
of high birth weight on subsequent asthma had a pooled RR of 1.2 (95% CI,
1.1, 1.3). There was consistency among the results in sensitivity analyses
examining studies containing only estimates of odds ratios, studies
containing only the outcome of physician-diagnosis of asthma, and studies
including all definitions of high body weight.
CONCLUSIONS:
Children with high body weight, either at birth or later in childhood, are
at increased risk for future asthma. Potential biological mechanisms include
diet, gastroesophageal reflux, mechanical effects of obesity, atopy and
hormonal influences. Further research might elucidate the causal pathway,
which could improve our understanding of the pathophysiology of asthma and
perhaps lead to knowledge of potential preventive interventions.
Reference:
Arch Dis Child. 2006 Jan 20 |