Atopy, obesity, and asthma in adults: the Humboldt study.
ABSTRACT Obesity appears more strongly associated with asthma in women than in men. It is hypothesized that a stronger linkage of obesity with nonatopic asthma than with atopic asthma may explain the sex difference. That being the case, we might hypothesize a stronger association between obesity and asthma in nonatopic individuals than in atopic ones. In this analysis, we examined the association between obesity and asthma in atopic and nonatopic people separately. A total of 1997 residents aged 18 to 79 years who participated in the 2003-2004 Humboldt study were included in the analysis. Body mass index (BMI) and waist circumference were objectively measured. Allergy skin tests were conducted to determine atopic sensitization. Respiratory allergy and physician diagnosed asthma were self-reported. Overall, 8% reported having asthma, 30% had atopic sensitization as determined by allergy skin tests, 31% reported a history of respiratory allergy, and 35% were obese defined as BMI equal to or larger than 30 kg/m(2). Compared to those with a BMI <25 kg/m(2), the odds ratio for asthma for the nonatopic subjects of those with a BMI of at least 30.0 kg/m(2) was 2.01 (95% confidence interval [CI]: 1.13, 3.59] after adjustment for sex and age. The association between obesity and asthma was not statistically significant in atopic subjects. The adjusted odds ratios for obesity versus normal weight were 2.56 (95% CI: 1.07, 6.12) and 1.76 (95% CI: 1.04, 3.01) for those without and with a history of respiratory allergy, respectively. The association of asthma with waist circumference was not statistically significant in all the subgroups defined by atopy and respiratory allergy. The data suggested a stronger association between obesity and asthma among nonatopic people than among atopic people.
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ABSTRACT: There is substantial evidence that obesity and asthma are related. "Obese asthma" may be a unique phenotype of asthma, characterized by decreased lung volumes, greater symptoms for a given degree of lung function impairment, destabilization or lack of asthma control, lack of eosinophilic inflammation and a different response to controller medication. Whether this relationship between obesity and asthma is causal or represents co-morbidity due to other factors is unclear. In previous reviews concerning the relationship between obesity and asthma, five hypotheses were put forth. One of these hypotheses is that a low grade systemic inflammation caused by adipokines from the fat tissue causes or enhances bronchial inflammation. In animal models, there is an increasing amount of evidence for the role of adipokines derived from fat tissue in the relationship between obesity and asthma. The data are conflicting in humans. Since obesity is a component of the metabolic syndrome and the metabolic syndrome is also a form of systemic inflammation, it is to be expected that there is a relationship between metabolic syndrome and asthma. The few data that are available show that there is no relationship between metabolic syndrome and asthma, but there is one between the metabolic syndrome and asthma-like symptoms. Further research is needed to confirm the relationship between obesity and asthma in humans, where a rigorous approach in the diagnosis of asthma is essential.Monaldi archives for chest disease = Archivio Monaldi per le malattie del torace / Fondazione clinica del lavoro, IRCCS [and] Istituto di clinica tisiologica e malattie apparato respiratorio, Università di Napoli, Secondo ateneo 09/2010; 73(3):116-23.