Third, the status of the baseline proteinuria, presence of sepsis, and etiology of AKI were not identified. Recently, these variables were identified as important factors affecting short- and long-term prognosis after AKI [21,40,41]. In this study, we included all available demographic data and clinical information for analysis, but residual confounding might still exist to some extent due to unmeasured and unknown risk factors. Last, this retrospective observational study cannot prove that AKI plays a causal role in CKD progression or that aggressive follow-up after discharge would improve these long-term outcomes, as there was no pre-specified protocol for post-discharge care and SCr follow-up. Prospective studies with structured, multidisciplinary, follow-up medical care for AKI survivors are warranted to clarify this issue [42].ConclusionsThe present study demonstrated the gradual decline in kidney function after hospital discharge in critically ill patients with AKI, who did not require dialysis. Furthermore, there appeared to be an association between the deterioration of kidney function and long-term mortality. This finding underscores the need to explore the mechanisms that are responsible for the long-term consequences of an AKI. Additionally, there is a need for novel strategies that focus on retarding renal function deterioration and strengthening the continuous surveillance of kidney function in AKI survivors.Key messages? Long-term trajectories of kidney function after AKI in critically ill survivors are not well-defined, especially in those who have not received dialysis. This issue is possibly overlooked in post-discharge medical care.? A considerable portion of critically ill patients, who survived AKI that did not require dialysis, had CKD during long-term follow-up.? We revealed that there was a steady long-term decline in kidney function after hospital discharge. Therefore, we should not view AKI only as a self-limiting acute disease, but also as a long-lasting progressive disorder.? The mortality risk increased significantly in a graded manner with the decline in kidney function from baseline eGFR to advanced stages of CKD during the follow-up period.? We need to organize multidisciplinary medical care for critically ill AKI survivors to continually monitor kidney function after discharge. One potential modifiable factor to improve long-term survival of patients with AKI after discharge from hospital is to prevent the deterioration of their kidney function.