The study protocol has been approved by the ethics committee of the Hospital Clínico San Carlos, which in is in accordance with the Helsinki Declaration. Every patient will be requested to sign the informed consent before inclusion in the trial. If patient's condition makes it unfeasible to obtain a signed informed consent, it will be requested to their next of kin. Prospective patients will be requested to sign the informed consent during hospital admission, whereas retrospective patients/relatives will sign the informed consent at the time of follow-up contact. The main investigator at each participating center will be responsible for its on-site obtainment and storage according to current Spanish law.