This observational study aims to evaluate the long-term effectiveness and safety of mepolizumab 300 mg/4 weeks in adults with eosinophilic granulomatosis with polyangiitis (EGPA) in the European real-life setting.
The main questions it aims to answer are:
* How effective is mepolizumab 300 mg/4 weeks over long-term follow-up in patients with EGPA?
* How safe is mepolizumab 300 mg/4 weeks during long-term treatment?
* What are the effects of switching mepolizumab dosage from 300 mg/4 weeks to 100 mg/4 weeks, or from 100 mg/4 weeks to 300 mg/4 weeks?
Participants already receiving mepolizumab as part of routine clinical practice. Researchers will retrospectively collect demographic, clinical, laboratory, and treatment-related data from medical records. For patients starting mepolizumab 300 mg/4 weeks, data will be collected from treatment initiation and during follow-up up to 60 months. For patients who change mepolizumab dose, data will also be collected at the time of dose switch and 3 months later.