What is the definition of Chronic Kidney Disease (CKD)?

From the Guidelines

Chronic Kidney Disease (CKD) is defined as the presence of important kidney damage or decreased kidney function for 3 or more months, with a glomerular filtration rate (GFR) less than 60 mL/min/1.73 m². This definition is based on the most recent evidence from the Canadian Society of Nephrology commentary on the KDIGO clinical practice guideline for CKD evaluation and management 1. The key components of this definition include:

• Kidney damage, which can be ascertained by markers such as persistent proteinuria, abnormalities in urine sediment, and abnormal findings on imaging studies
• Decreased kidney function, which is typically measured by GFR
• A duration of 3 or more months, to distinguish CKD from acute kidney injury It is essential to note that CKD is a condition characterized by gradual loss of kidney function over time, and it can be caused by various factors, including diabetes, high blood pressure, glomerulonephritis, polycystic kidney disease, and recurrent kidney infections. Symptoms of CKD may not appear until significant kidney damage has occurred and can include fatigue, swelling in legs and ankles, changes in urination, and high blood pressure. Management of CKD focuses on treating underlying causes, controlling blood pressure, managing blood sugar levels, and making lifestyle changes such as reducing salt intake and quitting smoking. In advanced stages, treatments may include dialysis or kidney transplantation. The disease is classified into five stages based on GFR levels, with stage 1 being the mildest and stage 5 (kidney failure) being the most severe. Early detection and treatment of CKD are crucial to prevent or delay adverse outcomes, and routine laboratory measurements can help identify earlier stages of the disease. According to the KDIGO guidelines, patients with CKD should be considered in the highest risk group for subsequent cardiovascular disease events, and most interventions that are effective in the general population should also be applied to patients with CKD. In patients with estimated GFR (eGFR) < 60 mL/min/1.73 m², urine protein assessment and a repeat measurement of kidney function should be undertaken to confirm the diagnosis of CKD. If the low GFR is likely long term, the repeat assessment could be in 3 months, which would satisfy criteria for CKD. However, if low GFR could be acute or subacute, the repeat assessment should be made sooner, sometimes within days, depending on the clinical situation. It is also important to consider the potential implications of labeling someone as having CKD, including insurance problems, and to use clinical judgment when evaluating patients with low GFR. Overall, the definition of CKD is crucial for identifying patients at risk of adverse outcomes and for guiding management and treatment decisions. By understanding the definition and classification of CKD, healthcare providers can provide optimal care for patients with this condition and improve their quality of life. The evidence from the Canadian Society of Nephrology commentary on the KDIGO clinical practice guideline for CKD evaluation and management 1 provides a comprehensive framework for defining and managing CKD, and it highlights the importance of early detection and treatment in preventing or delaying adverse outcomes. In conclusion, the definition of CKD is a critical component of managing this condition, and it should be based on the most recent evidence and guidelines. However, it is essential to prioritize the single most recent and highest quality study, which in this case is the Canadian Society of Nephrology commentary on the KDIGO clinical practice guideline for CKD evaluation and management 1. This study provides the most up-to-date and comprehensive guidance on defining and managing CKD, and it should be used to inform clinical practice and decision-making. By prioritizing this study and using its recommendations, healthcare providers can provide optimal care for patients with CKD and improve their morbidity, mortality, and quality of life outcomes.

From the Research

Definition of Chronic Kidney Disease (CKD)

• Chronic kidney disease (CKD) is a long-term condition characterized by gradual loss of kidney function over time 2.
• CKD is defined as decreased kidney function shown by glomerular filtration rate (GFR) of less than 60 mL/min per 1·73 m2, or markers of kidney damage, or both, of at least 3 months duration, regardless of the underlying cause 3.
• CKD can be asymptomatic, but it may be detected incidentally via urinalysis showing proteinuria or blood test results showing an elevated creatinine level 4.
• The Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equation is the most accurate creatinine-based method for estimating glomerular filtration rate (GFR) in routine practice 4, 5.

Key Characteristics of CKD

• CKD is characterized by damage to the renal glomeruli, vascular supply, and/or tubulointerstitium through complex processes involving inflammation, fibrosis, and hyperfiltration 4.
• Presence of proteinuria is associated with increased risk of progression of CKD and death 3.
• CKD can lead to complications such as anaemia, reduced red blood cell survival, iron deficiency, and mineral bone disease 3.

Diagnosis and Staging of CKD

• Diagnosis of CKD typically involves measuring serum creatinine and reporting estimated GFR based on serum creatinine (eGFRcr) using the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) 2009 equation 5.
• Initial assessment of albuminuria includes measuring urine albumin and creatinine in an untimed spot urine collection and reporting albumin-to-creatinine ratio 5.
• CKD is classified into stages based on estimated GFR, degree of proteinuria, and the cause 4.