90-day mortality in AKI-D and CKD5-D patients admitted to the ICU

Acute kidney injury (AKI) and chronic kidney disease (CKD)
are related conditions commonly encountered in intensive care.
While both may require renal replacement therapy (RRT), critically ill
patients with dialysis-requiring AKI have significantly higher mortality
and poor clinical outcomes than those with end-stage CKD. To compare
90-day mortality between patients with KDIGO stage 3 dialysis-requiring
AKI (AKI-D) and those with stage 5 dialysis-dependent CKD (CKD5-D)
admitted to the ICU. Secondary objectives were to identify independent
predictors of increased 90-day mortality among AKI-D and CKD5-D patients,
and to identify independent predictors of RRT at 90 days among patients
who experienced an episode of AKI-D. This retrospective, single-center
cohort study included adult patients with AKI-D or CKD5-D admitted to the
ICU of a private quaternary hospital in São Paulo, Brazil. The study was
approved by the Research Ethics Committee (CEP) of the Federal University
of São Paulo, with a waiver of informed consent. The primary outcome was
90-day mortality. Multivariable logistic regression was used to identify
independent predictors of mortality and dialysis dependence. A total of
2,377 patients were included: 1,878 (79%) with AKI-D and 499 (21%) with
CKD5-D. The overall 90-day mortality was 42.5%, significantly higher in
the AKI-D (50.3% vs. 13.2%; p <0.001) compared to CKD5-D group.
Independent predictors of 90-day mortality among AKI-D and CKD5-D patients
included older age, the need for vasoactive drugs, mechanical ventilation
and diagnosis of sepsis. Among 731 AKI-D survivors assessed at 90 days,
175 (23.9%) remained dialysis-dependent. Risk factors for persistent
dialysis dependence included older age, coronary artery disease, clinical
(non-surgical) admission, and higher baseline creatinine. The risk of
death in critically ill patients with AKI-D was more than three times
higher than in individuals with CKD5-D. Although both AKI-D and CKD5-D
patients experience loss of renal function, the factors correctable by
dialysis alone do not account for the mortality difference between these
groups. Rather, the severity of the acute illness, reflected by the need
for invasive mechanical ventilation and vasoactive drugs, emerged as key
determinants of short-term outcomes in this cohort.