Acute kidney injury: The plague of the new millennium

Abstract

Although not infectious, acute kidney injury (AKI) is pandemic. Interestingly, like infection by Yersinia pestis, AKI has “spread” to both high- and low-income countries (even if likely secondary to significantly different pathogenetic pathways), and its outcomes are bad worldwide [ 1 ]: the deadly burden of AKI affects up to 5,000 cases per million people per year and kills up to 50 % of patients requiring renal replacement therapy (RRT) secondary to AKI [ 2 ]. Again, similarly to the Black Death (Atra Mors, in Latin) pandemics which broke out between the fourteenth and the nineteenth century, we are fighting against a barely known enemy without a specific therapy to administer. Very differently from the plague, AKI is a syndrome and is caused by multiple etiologies, frequently occurring simultaneously. However, the exact damage occurring to kidneys’ structure and function, through multiple and complex pathophysiologic mechanisms, is largely unknown. This uncertainty led the medical community (only recently, about 10 years ago) to search for a standard AKI definition [ 3 ] which is able to conventionally describe that the abrupt decrease of kidney function is not an “on-off” disease, but it has a spectrum of phenotypes (currently known as “AKI stages”; see Chap. 2). The standard definition is unable to identify and differentiate AKI etiologies and somehow causes a “one-fits-all” issue: detractors of “consensus-based” definitions argue that, for example, a stage II septic AKI might not be clinically comparable to a stage II postabdominal surgery AKI [ 3 ]. At least, however, some light has been shed on the obscure epidemiology of AKI, and it is now clear that AKI occurs with a different incidence in different clinical settings [ 4 ], inevitably leading, regardless of etiology, to significantly worse outcomes as compared to non-affected (plagued) patients. Exactly as it happened before the availability of antibiotics during plague pandemics, prevention of AKI might represent today the most significant way to improve outcomes in those populations at risk of developing an acute renal dysfunction.