Short- and long-term outcomes of elderly patients with acute kidney injury to acute kidney disease

Abstract Objective Acute kidney disease (AKD) describes acute or subacute renal damage and/or loss of kidney function between 7 and 90 days after AKI initiation. Because there are few reports on AKD in older patients, the present study evaluated the risk factors and outcomes of AKD in older patients. Methods A retrospective, observational, multicenter cohort study was conducted on consecutive patients (≥ 75 years) admitted to Chinese PLA General Hospital between 2007 and 2022. AKI was diagnosed on the basis of the Kidney Disease: Improving Global Outcomes (KDIGO) SCr-based criteria. AKD was defined as AKI (KDIGO stage 1 or greater) that persisted for 7 days or longer. The outcomes included short- and long-term mortality and proportion of de novo chronic kidney disease (CKD). Results In total, 1395 elderly patients were included in the analysis, including 1245 (89.2%) patients who had de novo kidney injury (DNKI). Among those who had DNKI, 760 (61.0%) patients met the AKD criteria. Overall, 1121 (90.0%) patients were male, and the median age was 88 (IQR = 84 − 91). A lower baseline estimated glomerular filtration rate, higher sodium level, higher magnesium level, hypoalbuminemia, anemia, mechanical ventilation, renal replacement therapy, and increased AKI severity were associated with the development of AKD. Compared with early AKI recovery, progression to AKD was associated with increased 28-day mortality (time ratio [TR] = 0.427, 95% CI 0.298–0.599; P < 0.001), 90-day mortality (TR = 0.427, 95% CI 0.309–0.590; P < 0.001), 1-year mortality (TR = 0.499, 95% CI 0.394–0.631; P < 0.001) and de novo CKD (OR = 4.085, 95% CI 2.834–5.889; P < 0.001). Conclusions These findings highlight the importance of early AKI recognition and management to prevent the progression of AKI to AKD and long-term adverse outcomes.