Long-term outcome in ICU patients with acute kidney injury treated with renal replacement therapy: a prospective cohort study

Abstract

Background: In intensive care unit (ICU) patients, acute kidney injury treated with renal replacement therapy (AKI-RRT) is associated with adverse outcomes. The aim of this study was to evaluate variables associated with long-term survival and kidney outcome and to assess the composite endpoint major adverse kidney events (MAKE; defined as death, incomplete kidney recovery, or development of end-stage renal disease treated with RRT) in a cohort of ICU patients with AKI-RRT.

Methods: We conducted a single-center, prospective observational study in a 50-bed ICU tertiary care hospital. During the study period from August 2004 through December 2012, all consecutive adult patients with AKI-RRT were included. Data were prospectively recorded during the patients' hospital stay and were retrieved from the hospital databases. Data on long-term follow-up were gathered during follow-up consultation or, in the absence of this, by consulting the general physician.

Results: AKI-RRT was reported in 1292 of 23,665 first ICU admissions (5.5 %). Mortality increased from 59.7 % at hospital discharge to 72.1 % at 3 years. A Cox proportional hazards model demonstrated an association of increasing age, severity of illness, and continuous RRT with long-term mortality. Among hospital survivors with reference creatinine measurements, 1-year renal recovery was complete in 48.4 % and incomplete in 32.6 %. Dialysis dependence was reported in 19.0 % and was associated with age, diabetes, chronic kidney disease (CKD), and oliguria at the time of initiation of RRT. MAKE increased from 83.1 % at hospital discharge to 93.7 % at 3 years. Multivariate regression analysis showed no association of classical determinants of outcome (preexisting CKD, timing of initiation of RRT, and RRT modality) with MAKE at 1 year.

Conclusions: Our study demonstrates poor long-term survival after AKI-RRT that was determined mainly by severity of illness and RRT modality at initiation of RRT. Renal recovery is limited, especially in patients with acute-on-chronic kidney disease, making nephrological follow-up imperative. MAKE is associated mainly with variables determining mortality.

Keywords: Acute kidney injury (AKI); Acute-on-chronic kidney failure; Long-term survival; Major adverse kidney events (MAKE); Modality of renal replacement therapy; Renal recovery; Renal replacement therapy (RRT); Timing of renal replacement therapy.

Fig. 1

Study flowchart. PDMS patient data management system, AKI acute kidney injury, ICU intensive care unit, RRT renal replacement therapy

Fig. 2

a Kaplan-Meier survival curve over time for the whole cohort. b Kaplan-Meier survival curve over time for hospital survivors. c Kaplan-Meier survival curve stratified for continuous renal replacement therapy (CRRT) modality (P < 0.001 by log-rank test), intermittent hemodialysis (IHD), and slow extended daily dialysis (SLEDD)

Fig. 3

Renal recovery was defined as complete when estimated glomerular filtration rate (eGFR) was within 25 % of baseline eGFR. Incomplete kidney recovery was defined as those patients with an eGFR decrease of 25 % or more from baseline eGFR without need for dialysis. Dialysis dependence was defined as end-stage renal disease and permanent need for renal replacement therapy for >3 months

Fig. 4

The composite endpoint major adverse kidney events (MAKE) comprised the components death, dialysis dependence, and incomplete renal recovery. Renal recovery was defined as incomplete when estimated glomerular filtration rate (eGFR) decreased 25 % or more from baseline eGFR without need for dialysis. Dialysis dependence was defined as end-stage renal disease and permanent need for renal replacement therapy for >3 months. CKD chronic kidney disease