Kidney Failure Risk Calculator - 2- and 5-Year KFRE Risk
Use this kidney failure risk calculator with the Tangri 4-variable KFRE to estimate 2-year and 5-year risk from age, sex, eGFR, and urine ACR.
Kidney Failure Risk Calculator
Results
What Is a Kidney Failure Risk Calculator?
A kidney failure risk calculator is a clinical tool that turns a patient's age, sex, eGFR, and urine albumin-to-creatinine ratio into a 2-year and a 5-year probability of needing dialysis or a transplant.
- • CKD progression counseling in the clinic: Walking a patient with stage 3 or 4 CKD through a concrete 2-year and 5-year percentage so the conversation about dialysis, transplant, or conservative care is grounded in their own numbers.
- • Nephrology referral triage: Sorting patients with stable CKD G3-G4 between primary care and nephrology using a published 5-year risk threshold rather than an eGFR cutoff alone.
- • Kidney-replacement-therapy planning: Flagging patients whose 2-year risk is high enough to start the access-surgery, transplant-evaluation, or dialysis-education workflow before urgent-start dialysis becomes the only option.
- • Shared decision-making for conservative care: Helping older or highly comorbid patients see their personal probability of reaching treated kidney failure, which is a useful input into a conservative-care or hospice pathway conversation.
The number does not predict when an individual patient will reach kidney failure. It gives a population-level probability that a similar patient in the published derivation cohort reached treated kidney failure over the same time window.
Because the KFRE reads the eGFR input as the same number a GFR Calculator returns, the two tools can be used in the same clinic visit to move from the eGFR number to the 2-year and 5-year risk percentage without re-entering the labs.
How the KFRE Calculator Works
The calculator accepts age, sex, the most recent eGFR, and the most recent urine albumin-to-creatinine ratio, runs the Tangri 4-variable KFRE linear predictor, and returns a 2-year and a 5-year probability.
- age and sex: Patient age in years and patient sex (male=1, female=0). Age is in decades, centered at 70.36; sex at 0.5642.
- eGFR: Most recent CKD-EPI creatinine-based eGFR, used per 5 mL/min/1.73m² step, centered at 36.11.
- ACR and S0(t): Spot urine albumin-to-creatinine ratio in mg/g (log(ACR) centered at 5.137), plus a sex-specific 2-year or 5-year baseline survival S0(t).
The KFRE is a survival model rather than an incidence model, which is why the result comes from raising a baseline survival to a power. The same coefficients carry the 2-year and the 5-year risk without needing two separate equations.
Worked Example: 65-year-old male with CKD G3b and microalbuminuria
Age 65, male, eGFR 35, ACR 30.
LP = -0.43. 2-year = 1.6%, 5-year = 4.8%.
2-year 1.6%, 5-year 4.8%, CKD G3b, moderate risk
Worked Example: 55-year-old male with CKD G4 and macroalbuminuria
Age 55, male, eGFR 22, ACR 800.
LP = 2.71. 2-year = 31.6%, 5-year = 68.1%.
2-year 31.6%, 5-year 68.1%, CKD G4, very high risk
According to Tangri et al. - JAMA 2011 (KFRE derivation, PMID 21482743), the KFRE uses age, sex, eGFR, and log(ACR) with the published 4-variable coefficients of -0.2200, 0.2467, -0.5567, and 0.4510. The negative age coefficient is the published sign: at the same eGFR and ACR, a younger adult has a higher linear predictor than an older adult because of the derivation cohort's higher competing mortality in older patients.
The KFRE expects a urine albumin-to-creatinine ratio in mg/g. A paired ACR Calculator turns the raw urine albumin and creatinine into that single ratio.
Key Concepts Behind the KFRE Score
Four ideas carry most of the clinical meaning behind a KFRE result.
Treated kidney failure, not just low eGFR
The KFRE endpoint is treated kidney failure, defined in JAMA 2011 as chronic dialysis or kidney transplant. A conservative-care patient has a different trajectory than a transplant-listed patient with the same eGFR.
eGFR is only half of the story
Two patients with the same eGFR can have very different KFRE results because albuminuria, age, and sex each shift the risk substantially.
Albuminuria is the steepest driver
The log(ACR) coefficient of 0.4510 is the largest single weight. Dropping ACR with an ACE inhibitor, ARB, SGLT2 inhibitor, or finerenone often reduces the KFRE faster than the same percentage change in eGFR.
KFRE risk, not CKD stage alone
KDIGO classifies CKD by G-stage and A-stage, but KFRE is the better predictor of treated kidney failure. KDIGO 2024 uses a 5-year KFRE of 3-5% to trigger referral and 2-year of 10% or more to start KRT planning.
The KFRE is a population-level probability, so the 2-year and 5-year numbers are best read as the share of similar patients in the derivation cohort who reached treated kidney failure. They are not a personal deadline.
When the chart only carries a urine protein-to-creatinine ratio, a Protein Cr Ratio Calculator converts that into the albuminuria number the KFRE needs.
How to Use This Calculator
Treat the calculator as a structured readout of two labs and two demographics.
- 1 Enter the patient age: Use the patient's age at the time of the eGFR and ACR measurements.
- 2 Set the patient sex: Use the sex as recorded in the chart.
- 3 Enter the most recent eGFR: Use the most recent CKD-EPI creatinine-based eGFR in mL/min/1.73m². Values outside 2-60 are clamped.
- 4 Enter the urine ACR: Use the most recent spot urine albumin-to-creatinine ratio in mg/g. Do not substitute a 24-hour urine albumin value.
- 5 Read the result: Compare the 5-year risk to the KDIGO 2024 referral threshold (3-5% to consider, above 5% to refer) and the 2-year risk to the KRT threshold (10% or more).
A practical use: a 60-year-old man with type 2 diabetes has just had repeat labs. eGFR 28, ACR 320. The calculator returns 2-year about 11% and 5-year about 29%. The 2-year risk crosses the 10% KDIGO kidney-replacement-therapy planning threshold, and the 5-year risk sits in the very-high band well above the 5% nephrology-referral threshold. Next: same-week nephrology call, SGLT2 or finerenone review.
Because uncontrolled blood pressure is the single most common driver of CKD progression, a Blood Pressure Calculator sits naturally in the same clinic workflow.
Benefits of Using This Calculator
A KFRE result turns a list of labs into a number a patient can remember.
- • Concrete progression counseling: A 2-year and 5-year percentage is easier to anchor a CKD progression conversation around than an eGFR number.
- • Better referral triage: Aligns the referral decision with the published KDIGO 2024 5-year KFRE threshold.
- • Earlier KRT planning: A 2-year KFRE of 10% or more flags patients who need an arteriovenous fistula referral or transplant evaluation.
- • Documents the treatment effect: Re-running the KFRE after starting an ACE inhibitor, SGLT2 inhibitor, or finerenone shows the percentage change in risk.
- • Risk adjustment for QI: Risk-adjusting CKD populations with the KFRE makes quality-improvement work comparable across clinics.
Most reference cards print only an eGFR number. A calculator that holds the published KFRE linear predictor and the KDIGO 2024 referral thresholds is more useful because the same screen can be re-run after a treatment change.
Factors That Affect KFRE Results
Several inputs move the KFRE by tens of percent, and the calculator surfaces the most important ones in the result panel.
eGFR and how it was measured
The most recent eGFR is the largest single driver of the result, and the model was derived on the CKD-EPI creatinine-based eGFR. Switching to a cystatin-C-based eGFR for the same patient will usually lower the KFRE because cystatin C is less affected by muscle mass and diet.
Urine albumin-to-creatinine ratio (ACR)
The log(ACR) coefficient is the largest single weight in the linear predictor, and dropping ACR from 800 mg/g to 80 mg/g with a renin-angiotensin blocker or an SGLT2 inhibitor often cuts the 5-year KFRE by half or more.
Age, sex, and trajectory
Male sex and a younger age both raise the linear predictor at the same eGFR and ACR, because the original derivation cohort gave older patients a higher competing risk of death before reaching treated kidney failure. A falling eGFR or a rising ACR over the last 12 months should still push the clinical interpretation toward a higher risk than the snapshot KFRE suggests.
Cause of CKD and comorbidities
The model was derived on a mixed CKD cohort, but cause matters at the bedside. Diabetic kidney disease, IgA nephropathy, and autosomal dominant polycystic kidney disease often progress faster than the KFRE suggests, while stable hypertensive nephrosclerosis in an older patient can track the published number more closely.
- • The KFRE was derived and validated in adults 18-90 with CKD G3-G5 and an eGFR below 60. The result outside that range is an extrapolation.
- • The KFRE is a population-level probability, not a personal prediction. A 5-year KFRE of 20% means about a one-in-five chance of reaching treated kidney failure.
The calculator is meant to be read alongside the chart, the trend, and the clinical picture. The result should be re-run after every meaningful change in eGFR, ACR, or treatment.
According to QxMD / MDCalc - KFRE (4-variable), the calculator takes age, sex, eGFR, and urine albumin-to-creatinine ratio and reports 2-year and 5-year risk of treated kidney failure.
According to KDIGO 2012/2024 CKD Evaluation and Management Guideline, a 5-year KFRE of 3-5% is used to consider nephrology referral, and a 2-year KFRE of 10% or more is used to start planning for kidney replacement therapy.
A Cholesterol Ratio Calculator tracks the lipid ratios that drive most of the cardiovascular risk carried alongside a rising KFRE.
Frequently Asked Questions
Q: What is the kidney failure risk calculator?
A: The kidney failure risk calculator is a bedside tool that uses age, sex, eGFR, and urine albumin-to-creatinine ratio to estimate a 2-year and a 5-year probability of needing dialysis or a transplant, based on the Tangri 4-variable KFRE published in JAMA in 2011.
Q: How is the kidney failure risk equation (KFRE) calculated?
A: The KFRE combines age, sex, eGFR, and log(ACR) into a linear predictor, exponentiates the result, and uses a sex-specific baseline survival to convert the predictor into a 2-year and a 5-year probability of treated kidney failure. The published 4-variable coefficients are -0.2200 for age per 10 years, 0.2467 for sex, -0.5567 for eGFR per 5 mL/min/1.73m^2, and 0.4510 for log(ACR).
Q: What inputs does the calculator need?
A: The calculator needs four inputs: patient age in years, sex, the most recent eGFR in mL/min/1.73m^2 from the CKD-EPI creatinine equation, and the most recent spot urine albumin-to-creatinine ratio in mg/g.
Q: What kidney failure risk percentage is considered high?
A: The KDIGO 2024 CKD guideline suggests a 5-year KFRE of 3-5% as the range to consider nephrology referral and a 2-year KFRE of 10% or more as the trigger to start kidney-replacement-therapy planning.
Q: Can kidney failure risk go down over time?
A: Yes. The KFRE drops when eGFR stabilizes or improves, when ACR falls in response to a renin-angiotensin blocker, an SGLT2 inhibitor, or a non-steroidal MRA, and after weight loss or a lower-sodium, lower-protein diet.
Q: When should a high kidney failure risk trigger a nephrology referral?
A: A 5-year KFRE of 3-5% is the usual trigger to consider nephrology referral, and a 5-year KFRE above 5% is a strong reason to refer. A 2-year KFRE of 10% or more is the trigger to start the access-surgery, transplant-evaluation, and dialysis-education workflow before urgent-start dialysis.