About the Kidney Failure Risk Equation
This calculator implements the 4-variable Kidney Failure Risk Equation (KFRE), published by Navdeep Tangri and colleagues in 2011 and validated in more than 30 cohorts worldwide. It estimates the probability that a person with chronic kidney disease will progress to kidney failure treated with dialysis or transplant within 2 years and within 5 years, using four routinely available inputs: age, sex, estimated glomerular filtration rate (eGFR), and urine albumin-to-creatinine ratio (ACR).
How the calculation works
The KFRE is a Cox proportional-hazards model. Each input is centered on the value observed in the derivation cohort, multiplied by a fitted coefficient, and summed into a linear predictor:
Xβ = -0.2201 × (age/10 - 7.036) + 0.2467 × (male - 0.5642) - 0.5567 × (eGFR/5 - 7.222) + 0.4510 × (ln(ACR) - 5.137)
The linear predictor is then combined with a baseline survival probability at 2 years (0.9750) and 5 years (0.9370) using the formula Risk(t) = 1 - S0(t)exp(Xβ). Because eGFR falls and ACR rises with worsening kidney function, lower eGFR and higher ACR both push the predicted risk upward, while older age and male sex add smaller upward adjustments based on the coefficients above.
Who the equation applies to
The 4-variable KFRE was derived and validated in adults aged 18 to 90 with an eGFR between roughly 10 and 59 mL/min/1.73m² (chronic kidney disease stage 3 to 5) who were not yet on dialysis. Outside that eGFR and age range, or in acute kidney injury, dialysis patients, or kidney transplant recipients, the predicted probabilities have not been validated and should not be used.
Putting the result in context
There is no universal cutoff that defines "high risk," but UK NICE chronic kidney disease guidance points to a 4-variable KFRE 5-year risk of about 5% as a reasonable point to discuss nephrology referral, with higher urgency as the estimate climbs further. This calculator groups results into low, moderate, high, and very high bands to make the numbers easier to scan, not to deliver a diagnosis.
When to consult a professional
This tool performs the published KFRE arithmetic for education and planning. It does not diagnose kidney disease and does not replace laboratory-confirmed eGFR and ACR trends or a nephrologist's assessment. Any decision about referral, monitoring frequency, or treatment should be made with a licensed healthcare provider who knows the full clinical picture.