%0 Journal Article %T Does renal replacement therapy increase mortality in the ICU? %A David Pesta£ża %J Critical Care %D 2011 %I BioMed Central %R 10.1186/cc10071 %X A recent retrospective study published in Critical Care has questioned the use of RRT in critically ill patients, including those with severe AKI [4]. Compared with conservative treatment, RRT patients showed a higher mortality. The indication for RRT was at the discretion of the physician, and patients receiving RRT presented higher severity and renal impairment scores. After multivariate analysis correcting for severity of illness (Acute Physiology and Acute Chronic Health Evaluation II score and Sequential Organ Failure Assessment score), mortality remained higher in RRT patients. In a multivariate analysis in septic shock patients, however, we observed that both severity scores are not related to mortality, contrary to the maximum Sequential Organ Failure Assessment score [5]. The decision of starting RRT in many patients during their ICU stay may have been related to evolving factors not included in the analysis (worsening severity, overload, progressing hypoxemia, and so forth), which affect mortality but are not detected in the initial snapshot assessment. For instance, it is inconceivable that anuric patients did not receive RRT. On the other hand, the use of RRT in some patients with mild renal impairment may have increased morbidity.The study underlines the idea that RRT is not necessary in many patients presenting mild AKI in the ICU, but may be misleading if we accept that this therapy is deleterious in general.Monique M Elseviers and Robert L LinsWe appreciate the comments of Dr Pesta£ża and understand his concerns about a possible misinterpretation of the results by considering our findings in too general a manner.First, however, we have to rectify that the overall Stuivenberg Hospital Acute Renal Failure results published in this journal did not derive from retrospective observations but from a prospective study of 1,303 AKI patients consecutively admitted to the ICU. Furthermore, disease severity was initially investigated using the Stuivenberg Hospit %U http://ccforum.com/content/15/2/415