Need for renal replacement therapy in ICU is a marker of morbidity

Patients in the intensive care unit (ICU) with acute renal failure (ARF) who need renal replacement therapy (RRT) have a high mortality. There is a widely held view that RRT per se is the reason. The aim of our study was to verify this hypothesis. We retrospectively analysed the RIPUG database of 26,689 patients admitted to 21 ICUs in the UK between June 1989 and September 1996. 2394 patients (9%) had ARF of whom 650 (27.2%) were treated with RRT. We compared the ICU mortality rates of patients who needed RRT with outcome of patients in ARF without RRT and the impact of the number of associated failed organ systems (Table).

Table

ICU mortality of patients with ARF was higher in patients who needed RRT. Four hundred and twenty-seven (66%) of patients with ARF who needed RRT suffered from at least two additional failed organ systems, compared to 590 (36.7%) amongst patients with ARF who did not need RRT. There was no significant difference in mortality between patients with or without RRT if the same number of associated organ failures were accounted for. We looked at the temporal relationship between onset of systemic inflammatory response syndrome (SIRS) and start of RRT. Of all 353 patients who suffered from ARF for more than 3 days and required RRT, 335 patients fulfilled the criteria for SIRS either before or at time of initiation of RRT. ICU-mortality in this group was 54.3% compared to 44.4% amongst the 18 patients who developed SIRS after starting RRT (hospital mortality 63.3% versus 44.4%). This difference was statistically not significant. In patients with ARF the need for RRT should be viewed as a marker of severity of illness and not as a cause of death.