The primary objective of this study is to show that at hospitalization for a severe exacerbation of COPD, PCT-guided treatment regarding antibiotic use is non-inferior to usual care consisting of prednisolone and/or antibiotics, in terms of treatment failure at day 30. Treatment failure is defined as death, need for endotracheal intubation or vasopressors, renal failure, lung abcess/emphysema, development of pneumonia or rehospitalization within 30 days after inclusion.