[Epidemiology of acute renal failure]

Acute renal failure (ARF) incidence varies depending on whether the intensive care unit only or also general and specialist medicine departments are considered. In some cases, however, such as after major cardiosurgical operations, ARF can occur in up to 30% of patients. Most of ARFs in intensive care units are secondary to acute tubular necrosis occurring because of a multi-organ dysfunction syndrome. Factors most often associated with acute renal damage are: advanced age, volume depletion, arterial hypotension, massive bleeding, and sepsis. ARF often leads to complications for the following pathologies: serious liver disease, pancreatitis, pre-existing renal dysfunction, great burns, and cardiosurgical and vascular operations on large vessels. Among the so-called 'iatrogenic factors', contrast media and aminoglycosides are definitely the main cause of a rapid deterioration of renal function. Mortality is low for the isolated forms of ARF,whereas it peaks to 0-80% in multi-organ failures where co-existing pathologies often dominate. The mortality rate over the past 20 years has not changed, although pharmacological supports and especially dialysis instruments have improved. Patients are now older and older, affected by multiple pathologies and with poor recovery capacity. Mortality is higher among elderly patients, while toxic forms (from contrast media or from myoglobinuria) result generally in better outcomes. Patients with acute renal damage and oliguria have a worse prognosis than non-oliguric patients. Finally, some unfavorable prognostic factors include the prolonged use of high dose inotropic drugs, mechanical ventilation, cardiac failure and a septic state.