A new proteomic approach will be applied to serum and plasma samples obtained 1 month after the index hospitalisation. This approach includes 3 steps: 1) equalisation of circulating proteins (expose low-concentration proteins belonging to the "deep-proteome"); 2) Retention chromatography; and 3) protein separation using 2D-electrophoresis and Surface-Enhanced Laser Desorption/Ionisation Time-of-Flight (SELDI-TOF).