Characterisation of Asthma in Obese Subjects

Our hypothesis: Obese subjects with a physician's made diagnosis of asthma have a poorer asthma control than asthmatics with normal weight, less variability of peak expiratory flows (PEF) and bronchodilator response,increased induced sputum and systemic markers of inflammation and an increased prevalence of atopy. Obese subjects have an increased incidence of co-morbidities such as rhinosinusitis, gastroesophageal reflux and sleep apnea syndrome. This study aims to determine if, in comparison with asthmatics with a normal weight, paired for age and sex, obese subjects with asthma (all not using anti-inflammatory agents) show: * A more uncontrolled asthma, increased health care use and poorer quality of life * A reduced response to bronchodilators and diurnal variability of expiratory flows * More marked airway inflammation and evidences of a systemic inflammatory response * An increased prevalence of co-morbidities which can influence the report of respiratory symptoms or the severity of the disease, such as esophageal reflux symptoms, upper airway disease (rhinitis) and sleep apnea syndrome or other sleep disorder.