In most patients, avoiding the precipitating factors and combination of statin and RAS inhibitor are recommended. The benefit of prednisone is uncertain, but its dramatic impact has been underlined in several short retrospective series, even with moderate daily dosage (0,2-0,5 mg/kg). However, adverse side effects of steroid therapy in uremic elderly with CCE have not been assessed. In addition, the optimal duration of the treatment has not been assessed. The lack of randomized controlled trial in CCE precludes significant advances. The investigators decided to assess whether prednisone started early, at mild dosage and for a short period prevents death and progression to end-stage renal failure in patients with severe CCE, as compared to placebo.