Few studies analyzed the referral time to nephrologists and its impact on the patient outcome in a large cohort. The investigators described the incidence and determined the outcome with respect to renal function recovery, renal replacement therapy (RRT) requirement and in-hospital mortality of Hospital Acquired Acute Kidney Injury (HA-AKI) without nephrology referral (nrHA-AKI) and late referred HA-AKI patients to nephrologists (lrHA-AKI) compared with early referral patients (erHA-AKI). The patients included were admitted to the tertiary care academic center of Lausanne (Switzerland) between 2004 and 2008, in the medical and surgical services and in the intensive care unit (ICU).

Inclusion Criteria:

• Adult patients.
• Hospitalization in the medicine and surgery wards and in the intensive care unit.
• Hospitalized patients with acquired acute kidney injury according to the
• Acute Kidney Injury Network (AKIN)criteria.
• HA-AKI patients with no referral to the nephrologist (nrHA-AKI).
• HA-AKI patients referred late (more than five days [> 5 days]) to the nephrologist (lrHA-AKI).
• HA-AKI patients early referred (within five days after sCr increase) to the nephrologist (erHA-AKI).

Exclusion Criteria:

• Patients with AKI at the time of the hospital admission and during the first
• 48 hours after admission.
• Patients hospitalized in other wards.
• Children under 18.

This study population consisted of patients who were hospitalized in the medical and surgical departments as well as in the intensive care untis (ICU) of the University Hospital of Lausanne (Centre Hospitalier Universitaire Vaudois [CHUV]) that is a tertiary care academic medical center. Patients with AKI coming from ICU in the medicine or surgery wards, and patients from medicine or surgery wards, who required a transfer to ICU during the hospital stay, were also included whatever the cause of the transfer.