The risk was even higher for patients with more severe AKI, as defined by severe declines in kidney function. Mortality risk was elevated even for patients whose kidney function returned to normal after AKI, as it did in more than half of cases. "Impaired kidney function following hospital discharge explained only part of the increased long-term mortality risk associated with AKI," said Lafrance.

The study had several limitations: it used data collected for another purpose, did not include complete information on the serum creatinine test used to diagnose AKI, was mostly limited to men, and did not include information on causes of death. It also lacked data on the long-term risk of chronic kidney disease, a potential late complication of AKI.

Nephrologists have known that AKI is associated with a high risk of death in the hospital, but it has been unclear if this risk persists after the patient goes home. "Better understanding of the long-term outcomes after AKI may inform further studies and improve patient care after those events," Lafrance added.

Source: Journal of the American Society of Nephrology