A multi-centre, prospective, observational study of continuous patients who fulfil the definition of severe asthma and the criteria for mepolizumab (nucala; GSK) therapy. Patients have their daily physical activity recorded using triaxial accelerometry (DynaPort MoveMonitor; McRoberts) prior to treatment, and at 6 and 12 months of mepolizumab therapy (100 mg subcutaneously once every 4 weeks).
