Overweight seems to be a growing problem associated with diseases which are increase during the last decades. As an example both the BMI (Body Mass Index) and the asthma prevalence are increasing. The question is whether a link exists between these changes or whether the increase is independent of each other.
In the frame of a longitudinal repeated cross-sectional epidemiological study 4925 children in total have been medical checked up. A questionnaire was filled out by the parents. Among other things data were gathered concerning anamnesis, physical measurements, and physician diagnosed diseases, like asthma. Describing the overweight in children's age until 15 years the BMI was divided in percentiles <10%, 10 to 25%, 25 to 75%, 75 to 90%, >90% respectively >97%. The full data set was available for 3946 children (80.1% of all participants).
Descriptive: The lifetime prevalence of asthma was 7.1% (age group until 15 years). The BMI was for the overweight group of 6/8/15 year old kids; 18.1/20.1/24.5 kg/m2 and in the adiposity group 20.2/22.4/27.7 kg/m2 respectively. Frequent air way infections and parental predisposition enhance the risk for asthma (4.1 vs 10.9%); boys are more affected than girls (8.1 vs 6.1%). Starting with the 10%-BMI-percentile the asthma prevalence increases using the above mentioned intervals from 3.6% up to 8.3% for children with overweight (>90%-BMI-percentile). Analytical: The logistic regression adjusted for relevant confounders (gender, smoking and passive smoking, parental predisposition, pets (like cats), duration of breastfeeding, socioeconomic status) confirms the descriptive results. The BMI dependent adjusted Odds Ratio (aOR) (range) for asthma was 1.6 (95% CI, 1.0-2.7; P = 0.048).
The results clearly show that within the group of higher BMI more asthma will detected. Contrary to other studies this study may not confirm that the dependence on asthma from the BMI is bimodal since no higher asthma prevalence was observed in the lower and lowest BMI classes. Up to now this pilot study does not answer the question about the underlying processes.