Outcomes of critically ill patients with acute kidney injury and end-stage renal disease requiring renal replacement therapy: a case-control study.

BACKGROUND: This study aimed to evaluate and compare the characteristics and outcomes of patients with end-stage renal disease (ESRD) with those of matched controls of patients with acute kidney injury (AKI) requiring renal replacement therapy.

METHODS: A case-control study was performed at the intensive care units (ICU) of three tertiary-care hospitals between December 2004 and September 2007. Patients were admitted with life-threatening complications and were matched for age and for severity of illness and organ dysfunctions. Conditional logistic regression was used to identify factors associated with hospital mortality.

RESULTS: A total of 54 patients with ESRD and 54 patients with AKI were eligible for the study and were well matched. In general, clinical characteristics were similar. Nonetheless, comorbidities were more frequent in patients with ESRD, and patients with AKI more frequently required mechanical ventilation. ICU (43% versus 20%, P = 0.023) and hospital (50% versus 24%, P = 0.010) mortality rates were higher in patients with AKI. In addition, patients with AKI experienced longer ICU and hospitals stays. The SAPS II score had a regular ability in discriminating survivors and non-survivors, and tended to underestimate mortality in patients with AKI and overestimate in patients with ESRD. When all patients were evaluated, older age [OR = 1.05 (95% CI, 1.01-1.09)], poor chronic health status [OR = 3.90(1.19-12.82)] and number of associated organ failures [OR = 4.44(1.97-10.00)] were the main independent predictors of mortality. After adjusting for those covariates, ESRD was still associated with a lower probability of death [OR = 0.17 (0.06-0.050)].

CONCLUSIONS: ESRD patients with life-threatening complications had significantly better outcome than AKI patients.