Li Q, et al. - In this retrospective analysis of very elderly patients (≥ 75 years old) from the Geriatrics Department of the Chinese PLA General Hospital between January 2007 and December 2015, researchers compared the differences between the Kidney Disease Improving Global Outcomes (KDIGO) criteria of the 48-hour window and the 7-day window in the diagnosis of acute kidney injury (AKI). They also determined the link between the 48-hour and 7-day windows for diagnosis and 90-day mortality. They found higher 90-day mortality in 48-hour window AKI vs in 7-day window AKI. Lower sensitivity of the 48-hour KDIGO window definition was suggested. A significantly better correlation of the 48-hour KDIGO window definition with subsequent mortality was shown, indicating its appropriateness for clinical use.