The CHRONIBERIA index is the result of a collaborative project developed in different areas of Spain and Portugal, which was designed to find out the variables that influence the mortality after discharge and develop a prognostic index adapted to the current healthcare needs of chronic patients in an internal medicine ward. We used data from two prospective previous studies, one of them (CRONIGAL project) developed in the Healthcare Area of Santiago de Compostela in Galicia (North-Western Spain) and the other one (PLUPAR project) in Aragon (North-Eastern Spain) and also added new data from two similar cohorts recruited in two hospitals in Portugal (Pedro Hispano Hospital in Matosinhos and Santo Antonio Hospital in Porto). All the clinical units which participated in this project were composed by physicians with expertise in the field of chronic patient’s management.