If BMI is a risk factor for asthma then it should also be a risk factor for atopy. But it isn’t, according to this study. The suggestion is that either atopy or asthma may be being misdiagnosed. Atopy is diagnosed by objective tests.
Evidence from:
E von Mutius et al. Thorax. November (2001) Vol.56 #11 p 835.
Does body mass index (BMI) correlate with diagnosis of childhood asthma?
7505 children aged between 4 – 17 took part in the study.
Extensive background details and medical exam for status.
Physician diagnosis or treatment for asthma was used to identify asthmatics.
Relative to lowest quartile, BMI, top quartile OR = 1.77 (95% CI = 1.44 to 2.19)
BMI was not correlated with atopy.
Comment
Possible explanations include a high rate of false diagnosis (activity intolerance is used by many physicians as a clear sign of asthma or direct effect of being overweight on breathing or sensitisation of an inflammatory mechanisms?