Kidney Diseases beyond Nephrology Kidney diseases beyond nephrology—intensive care

The Beginning and Ending Supportive Therapy for the Kidney (BEST Kidney) investigators conducted a multinational, multicentre, prospective, epidemiological survey of acute renal failure (ARF) in intensive care unit (ICU) patients [1], with the intention of determining the association between outcome and different epidemiological parameters: period prevalence of ARF, aetiology, illness severity and clinical management of ARF. Examined patients were treated with renal replacement therapy (RRT) or fulfilled at least one of the pre-defined criteria for ARF. Predefined ARF criteria were oliguria, defined as urine output of <200ml in 12 h and/or marked azotaemia, defined as a blood urea nitrogen level >30mmol/l. The data were collected at 54 hospitals, in 23 countries. Of 29 269 critically ill patients admitted during the 16 months’ study period, 1738 (5.7%) had ARF during their ICU stay, including 1260 (4.3%) who were treated with RRT. Overall hospital mortality was 60.3%. The most common contributing factor to ARF was septic shock (47.5%). Approximately 30% of the patients had pre-admission renal dysfunction. 86.2% survivors were independent from dialysis at hospital discharge. Independent risk factors for hospital mortality included use of vasopressors, mechanical ventilation, septic shock, cardiogenic shock and hepatorenal syndrome. Crude mortality assessment shows that the overall hospital outcome of ARF has remained high today, and has not changed in the last 30 years: nevertheless such analysis is profoundly misleading. Patients with ARF treated in hospitals 30 years ago were mostly treated outside the ICU, did not require or receive mechanical ventilation or vasopressor drugs, were 20–30 years younger in age and their outcome was typically assessed retrospectively and in academic centres only. Despite such profound differences, indicating much greater illness severity for patients treated in 2005, the mortality of ARF has not increased, the duration of treatment has clearly decreased in terms of need for dialysis, time in ICU and time in hospital and the techniques of artificial renal support have also changed markedly [2]. It is a matter of fact, however, that 50–60% crude mortality associated with ARF will remain unchanged in the next decade or more as it most likely represents the level of performance acceptable to the healthcare system rather than a true reflection of its performance. In other words, as therapeutic capability improves and the system continues to accept a mortality of 50% as reasonable for these very sick patients, the healthcare system will progressively admit and treat sicker and sicker patients with ARF. In modern healthcare systems, hence, ARF and requirement for acute RRT has become an established reality.