Acute renal failure in patients with severe sepsis and septic shock–a significant independent risk factor for mortality: results from the German Prevalence Study

BACKGROUND Sound data about the prevalence of acute renal failure (ARF) among patients with severe sepsis and septic shock are lacking. Further, it is not known whether ARF is an independent risk factor for mortality in septic patients or merely an indicator of disease severity. METHODS A prospective cross-sectional one-day prevalence study was carried out in a representative sample of German ICUs, divided into five strata (\textless 200 beds; 201-400 beds; 401-600 beds; \textgreater 600 beds; university hospitals). 3877 patients were screened of whom 415 had severe sepsis and septic shock. RESULTS Fourteen patients (3.4%) had chronic dialysis-dependent RF and were excluded from analysis. Of the remaining 401 patients, 166 (41.4%) had ARF, as defined by a rise in creatinine above twice the upper limit of normal and/or a drop in urine output to \textless 0.5 ml/kg bodyweight. Median APACHE II score was 22 in patients with ARF and 16 in patients without ARF (p\textless 0.0001). Patients with severe sepsis/septic shock had an overall hospital mortality of 55.2%. Hospital mortality in patients with ARF was 67.3% and without ARF 42.8% (p\textless 0.0001). After adjustment for APACHE II score and age, ARF remained a significant independent risk factor for death [odds ratio (OR) 2.11, 95% confidence interval (CI) 1.27-3.52]. Mortality in septic patients was not associated with pre-existing, non-dialysis-dependent chronic kidney disease, whereas in dialysis-dependent patients with sepsis mortality increased to 86%. CONCLUSION In this representative survey in patients with severe sepsis/septic shock, prevalence of ARF is high with 41.4%. ARF represents a significant independent risk factor for mortality in these patients.