Outcome of patients with acute renal failure treated with intermittent or continuous renal replacement therapy depending on the initial diagnosis: a retrospective analysis

Introduction

The mortality of patients with acute renal failure (ARF) remains high (50-60%). Predictive variables of outcome include, age, altered previous health status, severity of illness, multiorgan failure, oliguria, cause of ARF [1]. We retrospectively analyzed all patients without pre-existing renal insufficiency, admitted to the surgical ICU between 1993 and 2000, who developed ARF, that was treated with renal replacement therapy (RRT).

Methods

Three hundred and six (2.9%) of a total of 13,191 admitted patients were included in the study. Age, sex, APACHE II score, renal function parameters, initial diagnosis (hemorrhargic shock, trauma, post-liver transplantation, post-cardiac surgery, sepsis/MODS, other) were recorded as independent variables. Renal replacement therapy (intermittent, continuous, both), days in the ICU, emergency admission, and treatment with vasoactive drugs were recorded as dependent variables. Primary outcome variables were death in the ICU, poor renal recovery (poor outcome) or favorable renal recovery. Statistical analysis was performed by multiple logistic regression.

Results

A total of 51% of patients with ARF died after the initiation of RRT (mortality of patients without ARF 7%). Patients with sepsis/MODS who developed ARF had a significantly higher mortality (68%) compared to all ARF patients (OR 0.18 [0.06-0.49]). A significantly better outcome, was noted for patients after liver transplantation (mortality 28%; OR 6.50 [1.50-33.58]). Besides the initial diagnosis, APACHE II score and length of ICU stay were significantly correlated with mortality of these patients. The progression of creatinine clearance during RRT was predictive for mortality during ICU stay and was 4.5 times lower at the end of therapy compared to surviving patients with initially comparable clearance values. However, poor (death, no renal recovery requiring dialysis post-ICU) or favorable (full renal recovery) outcome was independent of the type of RRT. The predictors were validated by a receiver operating characteristics (ROC) curve (AUC: 0.74).

Discussion

The overall incidence of patients with ARF, treated with RRT, and mortality of those patients was comparable to published data. Mortality was highest in patients with sepsis/MODS and post-cardiac surgery patients. Of those patients who survived, renal recovery was best after liver transplantation and hemorrhagic shock and worst in patients with sepsis/MODS and trauma. The progression of creatinine clearance predicted the outcome. Renal recovery was independent of the type of renal replacement therapy, as treatment was not randomized.