- Enter the earlier eGFR and its date — ideally a steady-state value from at least 3 months ago.
- Enter the most recent eGFR and its date (the second date must be after the first).
- The tool computes the annual slope, classifies the rate (improving / slow / moderate / rapid), and — if eGFR is declining and above 15 — estimates years to kidney failure at the current rate and at a 50%-slower treated rate.
- Read the verdict and recommended-action lines for next steps appropriate to the rate.
All computation runs in your browser; no values are stored or transmitted.
When to Use
Use this tool to quantify how fast kidney function is changing by computing the eGFR slope between two dated measurements, and to project an order-of-magnitude time to kidney failure (eGFR < 15). The slope classifies progression against the KDIGO definition of rapid decline (> 5 mL/min/1.73 m² per year) and frames how much an evidence-based intervention — by halving the rate — could extend the runway before kidney replacement therapy.
Appropriate population
Adults with CKD and at least two steady-state eGFR values separated by enough time (ideally ≥ 3 months, and longer is better) to give a meaningful rate. Most useful for counseling on trajectory, deciding referral and dialysis-access timing, and motivating risk-factor optimization by showing the projected benefit of slowing decline.
When NOT to rely on it
A two-point slope is statistically fragile — a single acute illness, dehydration, or laboratory variation can dominate the result. Do not use values drawn during acute kidney injury or non-steady states. The time-to-failure and "with treatment" figures are linear extrapolations, not predictions; real eGFR trajectories are often non-linear. For formal risk, use the Kidney Failure Risk Equation. Whenever possible, base trajectory on multiple points over time, not two.
Pearls & Pitfalls
Slowing the slope buys years
Halving the rate of decline can roughly double the time before kidney failure. This is the concrete payoff of blood-pressure control, maximal-tolerated RAAS blockade, and an SGLT2 inhibitor — use the projected extra years to motivate adherence.
Prefer multi-point trajectories
Whenever you have more than two values, judge the trend over the whole series rather than any single pair. Plot eGFR over time; a regression line through several steady-state points is far more reliable than a two-point slope and is less swayed by one outlier.
Pitfalls
(1) Never compute a slope across an AKI episode — the recovery or dip will distort it. (2) Short intervals magnify noise; favor measurements months apart. (3) The time-to-failure figure is a linear extrapolation and assumes a constant rate, which rarely holds. (4) An "improving" slope may reflect a hemodynamic effect (e.g., starting an SGLT2 inhibitor causes an early dip then stabilization) rather than true reversal — interpret in context.
Why Use It
The rate of eGFR decline is one of the strongest signals of CKD trajectory and a recognized surrogate endpoint in clinical trials: a steeper negative slope predicts earlier kidney failure, while flattening the slope is the central goal of nephroprotective therapy. Quantifying the slope turns "your kidney function is dropping" into a concrete number, identifies rapid progressors who need urgent optimization and access planning, and lets patients see the tangible payoff — extra years before dialysis — of blood-pressure control, RAAS blockade, and SGLT2 inhibition.
CKD Progression Calculator — eGFR Slope & Estimated Time to Kidney Failure
Enter two eGFR values with their dates to calculate the annual rate of decline and estimate time to kidney failure — at the current rate and with a treatment that halves the rate.
⚕ GFR slope = (eGFR₂ − eGFR₁) ÷ time in years. Rapid progression defined as >5 mL/min/year decline (KDIGO 2024). Time to ESKD estimated as (current eGFR − 15) ÷ annual decline rate. The "with treatment" projection assumes 50% reduction in decline rate with optimal RAAS blockade + SGLT2 inhibitor — consistent with DAPA-CKD and EMPA-KIDNEY trial data. This is a mathematical estimate, not a clinical prediction. Two-point slope calculations are inherently less reliable than multi-point trajectories.
Next Steps
Use the result to support — not replace — clinical judgment.
- Interpret the value against the targets shown in the calculator and the Evidence section below, in the context of the full clinical picture.
- Trend serial measurements rather than acting on a single result; confirm abnormal or unexpected values before changing management.
- Apply the relevant KDIGO / specialty-guideline threshold and document the indication.
- Escalate or refer to nephrology when results are out of range, rapidly changing, or discordant with the clinical picture — and discuss the implications with the patient.
Evidence & References
Formula & Equations
| Quantity | Equation |
|---|---|
| Time interval (years) | (date₂ − date₁) ÷ 365.25 days |
| eGFR slope (mL/min/1.73 m²/yr) | (eGFR₂ − eGFR₁) ÷ time in years |
| Estimated time to ESKD (years) | (current eGFR − 15) ÷ annual decline rate |
| Treated estimate (years) | (current eGFR − 15) ÷ (annual decline rate × 0.5) |
Progression-rate categories
| Category | Annual eGFR decline |
|---|---|
| Improving | eGFR rising (positive slope) |
| Slow | ≤ 2 mL/min/1.73 m²/yr (near normal aging) |
| Moderate | > 2 to ≤ 5 mL/min/1.73 m²/yr |
| Rapid (KDIGO) | > 5 mL/min/1.73 m²/yr |
Kidney failure (ESKD) is taken as eGFR < 15 for the time projection. The 50%-slowing scenario reflects the magnitude of benefit seen with SGLT2 inhibitors plus RAAS blockade in DAPA-CKD and EMPA-KIDNEY. These are linear extrapolations and should not be read as individual predictions.
Evidence & References
KDIGO defines rapid CKD progression as a sustained eGFR decline exceeding 5 mL/min/1.73 m² per year. A body of work led by Inker, Greene, and the NKF–FDA–EMA surrogate-endpoint consortium established eGFR slope as a validated surrogate endpoint for CKD trials, and the SGLT2-inhibitor outcome trials (DAPA-CKD, EMPA-KIDNEY) demonstrated that slowing the slope translates into fewer kidney-failure events.
- Kidney Disease: Improving Global Outcomes (KDIGO) CKD Work Group. KDIGO 2024 Clinical Practice Guideline for the Evaluation and Management of Chronic Kidney Disease. Kidney Int. 2024;105(4S):S117–S314.
- Inker LA, Heerspink HJL, Tighiouart H, et al. GFR Slope as a Surrogate End Point for Kidney Disease Progression in Clinical Trials: A Meta-Analysis of Treatment Effects of Randomized Controlled Trials. J Am Soc Nephrol. 2019;30(9):1735–1745.
- Heerspink HJL, Stefánsson BV, Correa-Rotter R, et al. Dapagliflozin in Patients with Chronic Kidney Disease (DAPA-CKD). N Engl J Med. 2020;383(15):1436–1446.
- The EMPA-KIDNEY Collaborative Group. Empagliflozin in Patients with Chronic Kidney Disease. N Engl J Med. 2023;388(2):117–127.
