Background
Renal failure in critically ill patients is perceived as a serious problem with high mortality.
Objectives
To compare the outcome of ICU patients with renal failure requiring renal replacement therapy (RRT) with that of patients without renal failure (defined by a serum creatinine <120 μmol/l) and to determine whether there is a difference in outcome between ICU patients with acute renal failure (ARF) treated with RRT and ICU patients with pre-existing dialysis-dependent end-stage renal failure (ESRF).
Methods
Retrospective analysis of the Riyadh ICU Program database of 41,972 patients admitted to 22 ICUs in the United Kingdom and Germany between 1989 and 1998.
Results
Table 1 presents the characteristics and outcome of patients with and without renal failure. Table 2 outlines the association between the maximum number of other failed organ systems (as defined by criteria of Knaus and colleagues, excluding renal failure) and ICU mortality in ARF patients and patients with ESRF.
Table 1.
| Total population | No renal failure | ARF and RRT | ESRF and RRT | |
|---|---|---|---|---|
| Number of patients | 41,972 | 29,225 | 1787 | 797 |
| Mean age (95% CI) | 60.5 (60.3–60.6) | 59 (59–59.4) | 60 (60–61) | 55 (54–56) |
| Male sex (%) | 63.5 | 61.8 | 67.4 | 59.6 |
| Median APACHE II score (day 1) | 13 | 11 | 23 | 21 |
| Length of stay in ICU (days) | 2 | 1 | 10 | 2 |
| ICU mortality (%) | 13.7* | 6.2* | 54.6* | 20.8* |
| Hospital mortality (%) | 18.8* | 10.3* | 62.3* | 34.5* |
| Standardized mortality ratio (%) | 1.08 | 0.86 | 1.49 | 0.97 |
* P < 0.0001.
Table 2.
| ARF and RRT | ESRF and RRT | ||||
|---|---|---|---|---|---|
| Maximum number of other failed organs | Proportion of patients (%) | ICU mortality (%) | Proportion of patients (%) | ICU mortality (%) | P value |
| 0 | 9.7 | 12.1 | 42 | 2.7 | < 0.0001 |
| 1 | 22.9 | 35.7 | 32.4 | 14.7 | < 0.0001 |
| 2 | 34.0 | 56.8 | 16.7 | 48.1 | NS |
| > 2 | 33.4 | 78.2 | 8.9 | 77.5 | NS |
Conclusions
The need for renal replacement therapy in the ICU was associated with an increased mortality. Patients who needed RRT for ARF had a longer stay in the ICU and a significantly higher mortality compared with patients who had RRT for pre-existing ESRF. This difference in outcome was most probably due to other factors, including number of associated failed organ systems.