Incidence, classification, and outcomes of acute kidney injury.

BACKGROUND

Traditionally the epidemiology of acute renal failure was assessed in patients requiring renal replacement therapy. Recent data emphasized the importance of less severe impairment of kidney function, hence the terminology acute kidney injury (AKI) was introduced.

METHODS

In this paper we present a review of current published data on the epidemiology of AKI.

RESULTS

The RIFLE classification categorizes the whole severity range of AKI into 3 severity categories and 2 outcome classes. AKI is associated with increased costs and worse outcomes. Increasing severity classes are associated with increasing morbidity and mortality. There is an increasing incidence of AKI, while mortality seems to decrease.

CONCLUSION

Small changes in kidney function have an impact on outcomes and this knowledge has led to the introduction of the terminology AKI, encompassing both discrete and severe impairment of kidney function. The RIFLE classification describes the whole range of AKI and has been validated in multiple cohorts. As a consequence of increasing comorbidity, the incidence of AKI is increasing. The incidence of acute renal failure requiring renal replacement therapy even compares to that of acute lung injury, and up to two thirds of general ICU patients meet RIFLE criteria for AKI.