1 Perioperative Transfusion Medicine, School of Medicine, University of Málaga, Málaga, 29071 Spain. Electronic address: mmunoz@uma.es.
2 Department of Internal Medicine, University Hospital Virgen de la Victoria, Málaga, Spain.
3 Department of Transfusion Medicine, San Camillo-Forlanini Hospital, Rome, Italy.
4 Department of Cardiac Surgery, European Hospital, Rome, Italy; Department of Biostatistics, Saint Camillus International University of Health and Medical Sciences, Rome, Italy.