nephrology & metabolismformula

Kidney Failure Risk Equation (KFRE)

The Kidney Failure Risk Equation estimates the 2- and 5-year probability of progression to kidney failure (requiring dialysis or transplant) in patients with CKD G3–G5. The 4-variable version uses age, sex, eGFR, and uACR.

inputs

years
Most useful for eGFR <60 (CKD G3–G5)
mL/min/1.73m²
mg/g

✓ when to use

Use in patients with CKD G3–G5 (eGFR <60) to guide nephrology referral timing, RRT preparation, and patient counselling. The KFRE helps answer the question 'when should this patient be referred to nephrology?' — a 2-year risk ≥3–5% is a commonly used referral threshold.

✗ when not to use

Not validated for eGFR ≥60 (CKD G1–G2) or for AKI. Requires a uACR measurement — not calculable from eGFR alone. The equation assumes stable CKD; acute changes in eGFR (e.g., AKI superimposed on CKD) will give misleading results. Not validated in children.

clinical pearls

  • KFRE helps avoid both over-referral (referring stable CKD G3a patients with <1% risk) and under-referral (missing CKD G3b patients with high albuminuria and >10% risk). It adds more information than eGFR alone.
  • uACR is critical — two patients with identical eGFR but different uACR can have vastly different kidney failure risks. Always measure uACR alongside creatinine.
  • A 2-year risk ≥3–5% is a reasonable nephrology referral threshold. A risk ≥10–15% should trigger RRT preparation (fistula creation takes 3–6 months; transplant workup takes 6–12 months).
  • The KFRE is available as an online calculator at kidneyfailurerisk.com. It provides both 2-year and 5-year risk estimates.
  • KFRE demonstrates that young patients with low eGFR and high albuminuria are at higher risk than elderly patients with similar eGFR but low albuminuria — this aligns with the KDIGO heat map and reinforces the importance of albuminuria in CKD risk stratification.

related tools

ckd-epi-2021eGFR calculationkdigo-akiAKI staging