Before initiation of mepolizumab, a recording of patient's demographics, clinical, physiological and inflammatory features will be recorded. All subjects will be reassessed for the above measures at 6, 12, 18 and 24 months.
In addition to the above visits, patients will be assessed every time they experience either moderate or severe exacerbation of asthma over the treatment period.
Based on the percentage of sputum eosinophils and neutrophils, the type of inflammatory exacerbation will be determined
