Twenty-five obese women (BMI over 30) and 25 non-obese women (18\>BMI\<25) considered to have severe asthma by their physician and requiring corticosteroids to control their asthma will have the following investigation:
* Respiratory questionnaires focussing on the nature and time-course of symptoms, asthma control criteria, medication use.
* Physical examination, including measures of BMI, waist, hips and ratio waist/hips
* Blood test for Complete Blood Count, blood glucose, total IgE levels and markers of systemic inflammation (C-Reactive Protein, fibrinogen…)
* Spirometry and bronchodilator response.
* Induced sputum analysis and Exhaled Breath Condensate pH to assess airway inflammation.
* Skin prick tests with a battery of common airborne allergens
* Measurement of lung volumes and airway resistance + MIP and MEP.
* Methacholine challenge (up to 16 mg/ml) with Borg scores for breathlessness and chest tightness.
