Obesity is not associated with mild asthma diagnosis in a population of Spanish adults.

BACKGROUND

Several studies have suggested a relationship between asthma and obesity. Moreover, atopy is an important risk factor for asthma, but the relationship between obesity and atopy is uncertain.

METHODS

A cross-sectional multicenter study was conducted in a population of Spanish adults between November 2007 and July 2008. The subjects included had experienced asthma symptoms in the last year but had a forced expiratory volume in 1 second (FEV(1))/forced vital capacity (FVC) > 70%. Mild asthma diagnosis was confirmed by measuring airway hyperresponsiveness to methacholine. Body mass index in kg/m(2) was used as measure of obesity. Subjects were considered atopic when they had at least one positive skin prick test to common aeroallergens. Adjusted odd ratios (OR) were obtained by logistic regression.

RESULTS

A total of 662 subjects were included and 234 subjects (35.3%) were diagnosed with asthma (consistent symptoms and positive methacholine test). After adjusting the model for age, gender, atopy, baseline FEV(1), and FEV(1)/FVC ratio, there was no association between overweight or obesity with asthma diagnosis, with OR of 0.889 (95% CI, 0.60-1.38) and 0.925 (95% CI, 0.577-1.48), respectively. A multivariable logistic regression analysis confirmed that atopy increases the risk of asthma (p = 0.008). The non-atopic obese group had an increased risk of asthma compared to the non-atopic group with normal weight or overweight (p = 0.0032).

CONCLUSIONS

In this study obesity was not associated with a diagnosis of asthma. The presence of atopy was a risk factor for asthma, independent of obesity. Obesity, however, may be a risk factor for the development of asthma among non-atopic subjects.