cell injury may identify additional patients with AKI and may identify the majority of patients at an earlier stage. Rationale for a guideline on AKI AKI is a global problem and occurs in the community, in the hospital where it is common on medical, surgical, pediatric, and oncology wards, and in ICUs. Irrespective of its nature, AKI is a predictor of immediate and long-term adverse outcomes. AKI is more prevalent in (and a significant risk factor for) patients with chronic kidney disease (CKD). Individuals with CKD are especially susceptible to AKI which, in turn, may act as a promoter of progression of the underlying CKD. The burden of AKI may be most significant in developing countries34,35 with limited resources for the care of these patients once the disease progresses to kidney failure necessitating RRT. Addressing the unique circumstances and needs of developing countries, especially in the detection of AKI in its early and potentially reversible stages to prevent its progression to kidney failure requiring dialysis, is of paramount importance. Research over the past decade has identified numerous preventable risk factors for AKI and the potential of improving their management and outcomes. Unfortunately, these are not widely known and are variably practiced Kidney International Supplements (2012) 2, 13–18 15 chapter 1.1 worldwide, resulting in lost opportunities to improve the care and outcomes of patients with AKI. Importantly, there is no unifying approach to the diagnosis and care of these patients. There is a worldwide need to recognize, detect, and intervene to circumvent the need for dialysis and to improve outcomes of AKI. The difficulties and disadvantages associated with an increasing variation in management and treatment of diseases that were amplified in the years after the Second World War, led in 1989 to the creation in the USA of the Agency for Health Care Policy and Research (now the Agency for Healthcare Research and Quality). This agency was created to provide objective, science-based information to improve decision making in health-care delivery. A major contribution of this agency was the establishment of a systematic process for developing evidence-based guidelines. It is now well accepted that rigorously developed, evidencebased guidelines, when implemented, have improved quality, cost, variability, and outcomes.36,37 Realizing that there is an increasing prevalence of acute (and chronic) kidney disease worldwide and that the complications and problems of patients with kidney disease are universal, Kidney Disease: Improving Global Outcomes (KDIGO), a nonprofit foundation, was established in 2003 ‘‘to improve the care and outcomes of kidney disease patients worldwide through promoting coordination, collaboration, and integration of initiatives to develop and implement clinical practice guidelines’’.38 Besides developing guidelines on a number of other important areas of nephrology, the Board of Directors of KDIGO quickly realized that there is room for improving international cooperation in the development, dissemination, and implementation of clinical practice guidelines in the field of AKI. At its meeting in December of 2006, the KDIGO Board of Directors determined that the topic of AKI meets the criteria for developing clinical practice guidelines. These criteria were formulated as follows: K AKI is common. K AKI imposes a heavy burden of illness (morbidity and mortality). K The cost per person of managing AKI is high. K AKI is amenable to early detection and potential prevention. K There is considerable variability in practice to prevent, diagnose, treat, and achieve outcomes of AKI. K Clinical practice guidelines in the field have the potential to reduce variations, improve outcomes, and reduce costs. K Formal guidelines do not exist on this topic. Summary Small changes in kidney function in hospitalized patients are important and associated with significant changes in shortand long-term outcomes. The shift of terminology from ATN and ARF to AKI has been well received by the research and clinical communities. RIFLE/AKIN criteria provide a uniform definition of AKI, and have become the standard for diagnostic criteria. AKI severity grades represent patient groups with increasing severity of illness as illustrated by an increasing proportion of patients treated with RRT, and increasing mortality. Thus, AKI as defined by the RIFLE criteria is now recognized as an important syndrome, alongside other syndromes such as acute coronary syndrome, acute lung injury, and severe sepsis and septic shock. The RIFLE/AKIN classification for AKI is quite analogous to the Kidney Disease Outcomes Quality Initiative (KDOQI) for CKD staging, which is well known to correlate disease severity with cardiovascular complications and other morbidities.39 As CKD stages have been linked to specific treatment recommendations, which have proved extremely useful in managing this disease,39 we have developed recommendations for evaluation and management of patients with AKI using this stage-based approach. 16 Kidney International Supplements (2012) 2, 13–18 chapter 1.1 Chapter 1.2: Methodology INTRODUCTION This chapter provides a very brief summary of the methods used to develop this guideline. Detailed methods are provided in Appendix F. The