Obesity and Asthma:a Specific Phenotype

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.

Inclusion criteria

• Will be women aged 18 years and over
• Will be in good health apart from asthma or obesity as determined by history and physical examination (No other condition that could influence the proposed tests).
• All will be non smokers or ex-smokers for more than six months with a smoking history of no more than 10 pack- years (i.e., one pack per day or its equivalent for 10 years.)
• Subjects will have a physician's made diagnosis of severe asthma and treated with corticosteroids.

Exclusion criteria

• Subjects who are, in the opinion of the investigator, mentally or legally incapacitated thus preventing informed consent from being obtained.
• Subjects having a co-existing illness that precludes them from the trial.
• Pregnancy or lactation
• Contraindication to the prednisone treatment.