Patients: 127 elderly patients with acute kidney injury (AKI) from 6/2007 to 2/2011 at the department of Nephrology and Dialyis Center, HCMCity, Vietnam were divided into 2 groups: hospital-acquired AKI (HA-AKI) (n= 39) and community-acquired AKI (CA-AKI) (n=88) Method: observational, prospective and controlled.