Renal continuum: classification problems

Disease classification is one of the most serious challenges in modern medicine. New data on disease etiology, pathogenesis, diagnosis, treatment and prognosis lead to the revision of existing principles for the classification of pathological conditions. This is also true about kidney disease. In renal continuum, the first three months from the disease onset are defined as acute kidney injury or acute kidney disease. Chronic kidney disease implies renal structural or functional damage which is observed for more than three months, or markers of kidney damage, regardless of etiology. Despite the apparent simplicity of the renal continuum, there are difficulties in diagnosing and determining the event sequence. Currently, there is no consensus on the place of acute kidney disease in the renal continuum. Therefore, despite high prevalence acute kidney disease is rarely diagnosed, included in the diagnosis or taken into account while assessing the patient prognosis. The authors propose a new classification of renal continuum, which allows us to clarify the criteria for acute kidney disease and acute kidney injury. The suggested classification can be easily used in routine clinical practice. The introduction of biomarkers into wide clinical practice and the clarification of the criteria for acute kidney injury do not affect the proposed classification, but only clarify the criteria for diagnosing acute kidney injury, acute kidney disease, and chronic kidney disease.