The 5-Stage Chronic Kidney Disease (CKD) staging system is a standardised framework that classifies the severity of kidney impairment based on an individual’s estimated glomerular filtration rate (eGFR) and markers of structural damage – with Stage 5 CKD being the worst level of kidney function (kidney failure; GFR < 15 ml/min), and Stage 1 CKD being the best (GFR > 90 ml/min). Normal GFR is 90-120 ml/min.
It was developed by the US National Kidney Foundation (NKF) and published in 2002, to replace vague terminology like ‘chronic renal failure’ (CRF) with an objective, international language (Levey, 2003).
Also the word ‘failure’ was a misnomer (and frightened patients) as the kidneys of most people with CKD are not failing. They just have a reduction in the level of kidney function – which is often mild, stable, age-related and a disease.
The system was specifically designed to reduce the widespread underdiagnosis of End Stage Kidney Disease (ESRD), simplify collaborative clinical research, and catch high-risk patients early enough to delay or prevent the need for dialysis.
Note. GFR is derived mathematically from the blood creatinine level, and adjusted for age and gender.
Pro 1: Boosted Global Awareness and Funding
The framework transformed nephrology into a public health priority. By establishing distinct stages, it stimulated massive clinical research, elevated kidney health on global agendas, and raised awareness at both population and patient levels.
Pro 2: Reduced Underdiagnosis Over Creatinine Testing
Relying solely on raw blood creatinine previously caused clinicians to miss millions of asymptomatic patients. Shifting to an eGFR-based framework catches early-stage impairment, enabling timely interventions that delay or prevent dialysis.
Pro 3: Established a Universal Medical Language
The system provided an objective, standardised shorthand worldwide. Replacing vague terms like ‘chronic renal failure’ with clear stages (1 to 5) streamlined international clinical trials, epidemiological surveys, and collaborative data sharing.
Pro 4: Early Identification of Cardiovascular Risk
By pairing functional metrics (eGFR) with structural markers (uACR), the system acts as an early warning network.
It flags individuals at high risk for cardiovascular events (e.g. angina, heart attacks and heart failure) and progressive decline, allowing for proactive, preventative monitoring.
Pro 5: Driven Laboratory Standardisation
Widespread adoption forced global laboratories to standardise serum creatinine reporting.
This systemic push drove the medical community to phase out inaccurate formulas in favor of more precise tools, culminating in the modern CKD-EPI equation.
Con 1: Methodological Imprecision and eGFR Flaws
A major flaw stems from relying on mathematical estimations rather than direct measurements.
Early equations frequently underestimated true kidney function above 60 mL/min, meaning healthy individuals were erroneously flagged with kidney function impairment.
Con 2: Widespread Over-Diagnosis in the Elderly
Setting a rigid threshold of eGFR < 60 mL/min for Stage 3 labels roughly 10% of the world with a chronic disease (!). This is clearly not true.
This causes massive over-diagnosis in older demographics, whose lower eGFR often reflects normal, age-related decline.
Con 3: Arbitrary Thresholds and ‘Cancer Stage’ Panic
The boundaries separating stages are inherently arbitrary.
Furthermore, borrowing ‘staging’ terminology from oncology causes unnecessary patient anxiety; as people mistake a mild, stable ‘Stage 3 CKD’ kidney reading for an aggressive, terminal illness.
Con 4: Complete Omission of Disease Pathology – CKD is not a Diagnosis
The current system categorises patients purely by numerical function, ignoring the underlying cause of the damage.
CKD is not a diagnosus. It is a clinical syndrome with causes (there are many). This numbers-first approach can foster diagnostic laziness – with doctors not bothering to look for a cause, and hence may miss a treatable one.
When a doctor has diagnosed CKD, he/she needs to ask 2 further questions: “What is the renal pathology?” and “Do I need to do intensive investigation, possibly including a kidney biopsy?”
Con 5: Over-Simplification of a Complex Syndrome
Compressing complex renal medicine into basic, colour-coded grids over-simplifies the disease.
This can give junior doctors and students a false sense of security; leading them to treat the chart numbers instead of assessing the actual patient in front of them, in the traditional way, i.e. history, examination and investigation.
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