Unmet clinical need in patients with acute kidney injury and acute kidney disease: insights from a Korean multicenter cohort
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Acute kidney injury (AKI) is a common and serious condition that affects approximately 20% of hospitalized patients and 50% to 60% of those in the intensive care units (ICU). Approximately 40% of patients develop severe AKI, and nearly 70% require dialysis [1]. The incidence of AKI has been steadily rising in Korea, with patient numbers increasing by over 40% in the past 5 years and annual healthcare expenditures doubling during the same period [2]. Severe AKI requiring continuous kidney replacement therapy (CKRT) in the ICU is associated with an in-hospital mortality rate approaching 80%, representing not only a critical clinical challenge but also a substantial socioeconomic burden.
Although early and appropriate management of AKI can lead to full recovery, unresolved cases may progress to acute kidney disease (AKD), a transitional phase characterized by subacute kidney dysfunction occurring 7 to 90 days after AKI onset [3]. AKD significantly increases the risk of new-onset chronic kidney disease (CKD), progression of preexisting CKD, end-stage kidney disease (ESKD) [1], cardiovascular complications, and mortality [4,5]. Importantly, patients who develop AKD after severe AKI requiring CKRT are at a higher risk of progression to ESKD than those with stable CKD stage 4 or 5 who have not experienced AKI. Notably, even those who appear to have recovered kidney function within 90 days post-AKI are at a greater risk of adverse long-term renal outcomes than patients with stable CKD stage 3 [6]. These findings underscore the need for careful monitoring and follow-up beyond the acute phase, regardless of apparent recovery.
Despite its clinical importance, research on AKD in Korea remains limited and no large-scale national cohort has yet been established. To address unmet clinical needs, and with support from the Korea Disease Control and Prevention Agency, a Korean research group has established both prospective and retrospective multicenter cohorts of patients with AKD, titled the consortium LINking health medical records, biospecimens, and biosignals in Korean patients with Acute kidney injury (LINKA) [7].
This retrospective cohort included adult patients in the ICU who underwent CKRT between January 2017 and June 2022 across eight tertiary hospitals. The exclusion criteria included death within 90 days post-CKRT, preexisting maintenance dialysis, and lack of baseline or 90-day renal function data, resulting in a final cohort of 1,474 patients.
Although modest in size, this cohort represented a highly vulnerable and clinically significant population. Despite surviving critical illness and severe AKI requiring CKRT, these patients demonstrated persistently high mortality rates. The 1-year all-cause mortality rate consistently approached 20% each year (Fig. 1), which is substantially higher than that observed in other Korean cohorts such as KNOW-CKD (KoreaN cohort study for Outcome in patients With Chronic Kidney Disease), where only 50 deaths occurred during a comparable period with a similar number of patients [8]. When viewed alongside national cancer survival statistics—5-year survival rates of 72.9% for all cancers and 68.7% excluding thyroid cancer—our findings suggest that short-term outcomes in this population are even poorer than those in cancer patients. Mortality was notably higher among patients aged ≥65 years and those with diabetes (Fig. 2), highlighting the relevance of our findings in the context of an aging society with increasing rates of chronic disease.
The 1-year all-cause mortality rate in LINKA cohort population by year.
LINKA, LINking health medical records, biospecimens, and biosignals in Korean patients with Acute kidney injury.
Long-term mortality by age and diabetes mellitus.
(A) Comparison of 1-year, 3-year, and 5-year mortality rates based on age 65 years. (B) Comparison of 1-year, 3-year, and 5-year mortality rates based on diabetes mellitus.
Follow-up of kidney function at three months in this retrospective cohort revealed that approximately 60% of the patients developed AKD. Compared with those who recovered renal function, patients who progressed to AKD had a 25-fold increased risk of remaining dialysis-dependent and a 30% higher risk of mortality. These findings highlight the importance of short- and long-term management of AKI. Regular assessment of kidney function and continued care by nephrologists are essential to identify AKD early and mitigate the risk of further renal deterioration and death through the ongoing management of modifiable risk factors.
Currently, multiple studies utilizing the LINKA database are underway, each exploring different aspects of AKI and AKD spectra and current practices in CKRT. As a result, we anticipated gaining important insights into the clinical factors influencing the development and prognosis of AKI and AKD. These findings may guide effective strategies for the monitoring and management of high-risk patients.
Notes
Conflicts of interest
All authors have no relevant conflicts of interest to declare.
Funding
This research was supported by the National Institute of Health research project (project No. 2023-ER1105-00). This study was also supported by a cooperative research fund from the Korean Society of Nephrology (2023).
Data sharing statement
The data presented in this study are available from the corresponding author upon reasonable request.
Authors’ contributions
Conceptualization: JNA, SSH, SGK
Data curation: JNA, DY
Formal analysis: DY
Funding acquisition, Project administration: SGK
Investigation: JNA
Supervision: SSH, SGK
Visualization: DY, SSH
Writing–Original Draft: JNA
Writing – Review & Editing: JNA, SSH
All authors read and approved the final manuscript.