Chronic Kidney Disease Stages

Subdivision of patients with CKD at a stage depending on GRF provides a universal, simple and convenient system that allows assessing the risk of ESRD and cardiovascular complications, planning a nephroprotective and cardioprotective strategy, and timely resolving the issue of starting renal replacement therapy. Given that patients with one stage of CKD are heterogeneous in the course of the disease and the risk of cardiovascular complications, it is proposed to further index them by the severity of albuminuria/proteinuria.

It should be emphasized that the concept of CKD does not cancel the nosological approach to the diagnosis of kidney disease. It is necessary to seek identification of a specific cause (or causes) of the kidney damage development in order to establish a nosological diagnosis and prescribe etiotropic and pathogenetic therapy. It is recommended that the diagnosis of CKD be indicated after the underlying disease, with the disease coding in accordance with the ICD for the underlying disease.

For the first stage of CKD, it is proposed to use the code N18.1, for the second – N18.2, for the third – N18.3, for the fourth – N18.4, for the fifth – N18.5. Code N18.9 to indicate CKD of an unspecified stage is used instead of the term “Chronic renal failure, unspecified”.

Thus, the concept of CKD is more universal. It covers all stages of kidney disease, including the initial ones. It is more consistent with the objectives of prevention and nephroprotection than the old term “chronic renal failure” (CRF). The development of the concept of CKD means a shift in emphasis from the terminal stages, at an early stage. It ensures the continuity of patient management.

Previously, there were no unified approaches to the study of function and assessment of its violation severity. The terminological vagueness, ambiguity, ambiguous understanding of such definitions as “chronic renal failure”, “renal insufficiency”, “end-stage renal disease” did not allow doctors in different countries and centers to speak the same language, compare epidemiological data, treatment standards, and recommendations.

CKD stages determine the severity of the disease. Classification of CKD includes 5 stages:

• Stage 1: Normal GFR (≥90 ml/min / 1.73 m2) in combination with persistent albuminuria or a known pathology of the kidney structure/hereditary pathology.
• Stage 2: GFR 60–89 ml/min/1.73 m2.
• Stage 3a: 45–59 ml/min/1.73 m2.
• Stage 3b: 30–44 ml/min/1.73 m2.
• Stage 4: GFR 15–29 ml/min/1.73 m2.
• Stage 5: GFR <15 ml/min/1.73 m2.