Lohse R, et al. - In this retrospective analysis of 5927 ICU patients, researchers compared the outcomes of those with end-stage renal disease (ESRD) to those requiring acute renal replacement therapy (RRT). The use of chronic RRT >90 days before admission was the accepted definition of ESRD in this study. Acute RRT was used in 1004 patients (17%) and pre-existing ESRD requiring RRT was noted in 161 (3%). For acute RRT vs ESRD patients, 42% vs 28%, respectively, were the 30-day mortality, and 16% for those not requiring RRT (compared to ESRD patients). Compared with 90-day ESRD non-survivors, the following features were noted in ninety-day ESRD survivors: young age, less severely ill and needed less vasopressor treatment. A high crude mortality was reported in patients with pre-existing ESRD. On adjustment for confounders, short-term mortality was found to be within the range of those not receiving RRT. With respect to the short-term prognosis of RRT patients in the ICU, more significance of severity of acute illness and the burden of comorbidities was suggested rather than of the lack of kidney function per se.