- Obtain the patient's kidney biopsy report for a confirmed ANCA-associated glomerulonephritis (GPA or MPA).
- Select the percentage of normal (non-sclerotic, non-crescentic) glomeruli — >25% (N0), 10–25% (N1), or <10% (N2).
- Select the extent of tubular atrophy / interstitial fibrosis (IFTA) — ≤25% (T0) or >25% (T1).
- Enter the eGFR at diagnosis in mL/min/1.73m². The score, risk group, and approximate 3-year ESKD risk update automatically.
All computation runs in your browser; no values are stored or transmitted.
When to Use
Use the ANCA Renal Risk Score in a patient with biopsy-proven ANCA-associated glomerulonephritis (granulomatosis with polyangiitis or microscopic polyangiitis with renal involvement) at the time of diagnosis. The score requires a kidney biopsy: it reads the percentage of normal glomeruli and the extent of tubular atrophy / interstitial fibrosis off the histology report, then combines these with the eGFR at diagnosis to stratify the risk of progressing to end-stage kidney disease (ESKD) over roughly three years.
Appropriate population
Adults with newly diagnosed, biopsy-confirmed ANCA-associated glomerulonephritis. The score is most useful at baseline — to counsel patients on the likelihood of needing dialysis and to frame conversations about the intensity and duration of immunosuppression and renal-recovery expectations.
When NOT to rely on it
The score predicts kidney (ESKD) outcome, not patient survival, and it does not by itself dictate therapy — every patient with active ANCA glomerulonephritis warrants induction immunosuppression regardless of risk group. It requires an adequate kidney biopsy; it cannot be computed without histology. It was derived and validated in specific cohorts, so apply it as one input alongside ANCA serology, disease activity, comorbidity, and the full clinical picture rather than as a stand-alone decision rule.
Pearls & Pitfalls
Three histology + lab parameters, one number
The score adds three components: normal glomeruli (N0 = 0, N1 = 4, N2 = 6 points), tubular atrophy / interstitial fibrosis (T0 = 0, T1 = 2 points), and eGFR at diagnosis (G0 = 0, G1 = 3 points). The total (0–11) maps to a risk group: Low (0 points), Medium (2–7 points), and High (8–11 points), with approximate 3-year ESKD risks of ~0%, ~26%, and ~68% in the development cohort.
What "normal glomeruli" means here
The glomerular parameter counts the percentage of normal glomeruli — those without sclerosis, crescents, or necrosis — not the percentage that are abnormal. A higher proportion of preserved glomeruli is protective (N0), while <10% normal carries the heaviest weight (N2 = 6 points), reflecting how little salvageable parenchyma remains.
Pitfalls
(1) The score needs an adequate biopsy with enough glomeruli to estimate the normal fraction reliably; a small or non-representative sample weakens it. (2) It predicts kidney outcome only — it says nothing about patient mortality, relapse risk, or extrarenal disease. (3) It does not select therapy: a Low-risk patient still has active vasculitis requiring induction. (4) Use the eGFR at the time of diagnosis/biopsy; a value drawn after the start of treatment or after dialysis is not the validated input.
Why Use It
Prognosis in ANCA-associated glomerulonephritis varies widely, and clinicians and patients both want an early, evidence-based estimate of how likely the kidneys are to fail. The ANCA Renal Risk Score distills the most predictive histologic and functional features at diagnosis into a single number that reliably separates patients into Low, Medium, and High risk for ESKD over the first few years. That stratification helps counsel patients on dialysis risk, frame realistic expectations of renal recovery, and inform the intensity and duration of immunosuppression and supportive care. It complements our International IgAN Prediction Tool — together they cover prognostication for the two major primary glomerular diseases seen in nephrology practice. Note that the score predicts kidney survival, not patient survival, and never replaces the decision to treat active vasculitis.
ANCA Renal Risk Score
Select the three biopsy/lab parameters below. The score (0–11), the risk group, and the approximate 3-year ESKD risk update automatically once all three are entered.
⚕ Brix SR, et al. Kidney Int. 2018;94(6):1177–1188. The ANCA Renal Risk Score predicts the risk of end-stage kidney disease in ANCA-associated glomerulonephritis from biopsy and baseline eGFR. The ~3-year ESKD figures (Low ≈ 0%, Medium ≈ 26%, High ≈ 68%) are from the development cohort. The score predicts kidney outcome, not patient survival, and does not by itself dictate therapy. For licensed clinicians; not a substitute for individualized assessment.
Next Steps
Use the risk group to frame prognosis and counseling — not to decide whether to treat the vasculitis (all active disease warrants induction immunosuppression).
- Low risk (0 points): an excellent renal prognosis (~0% ESKD at 3 years in the development cohort). Reassure the patient about kidney survival while still delivering standard induction therapy and monitoring for relapse.
- Medium risk (2–7 points): an intermediate prognosis (~26% ESKD at 3 years). Counsel on a meaningful but not majority risk of kidney failure; optimize induction and supportive care and follow function closely.
- High risk (8–11 points): a guarded renal prognosis (~68% ESKD at 3 years). Discuss the substantial likelihood of needing dialysis, plan early for access and renal-replacement options, and weigh the intensity and risks of immunosuppression against the chance of meaningful recovery.
- Pair prognostication with the International IgAN Prediction Tool for the other major glomerular disease, and confirm function with the eGFR (CKD-EPI 2021) calculator.
Evidence & References
Scoring
| Parameter | Category | Points |
|---|---|---|
| Normal glomeruli (N) | >25% (N0) | 0 |
| 10–25% (N1) | 4 | |
| <10% (N2) | 6 | |
| Tubular atrophy / IF (T) | ≤25% (T0) | 0 |
| >25% (T1) | 2 | |
| eGFR at diagnosis (G) | >15 mL/min/1.73m² (G0) | 0 |
| ≤15 mL/min/1.73m² (G1) | 3 |
Risk Groups & 3-Year ESKD Risk
| Total score | Risk group | ~3-yr ESKD risk* |
|---|---|---|
| 0 points | Low | ≈ 0% |
| 2–7 points | Medium | ≈ 26% |
| 8–11 points | High | ≈ 68% |
*Risk of end-stage kidney disease at 36 months in the development cohort (Brix et al., 2018: 0%, 26%, and 68% for the Low, Medium, and High groups; an independent validation cohort reproduced 0%, 27%, and 78%). The score predicts kidney survival, not patient survival.
References
- Brix SR, Noriega M, Tennstedt P, et al. Development and validation of a renal risk score in ANCA-associated glomerulonephritis. Kidney Int. 2018;94(6):1177–1188. doi:10.1016/j.kint.2018.07.020.
- Berden AE, Ferrario F, Hagen EC, et al. Histopathologic classification of ANCA-associated glomerulonephritis. J Am Soc Nephrol. 2010;21(10):1628–1636. doi:10.1681/ASN.2010050477.
- Kidney Disease: Improving Global Outcomes (KDIGO). KDIGO 2021 Clinical Practice Guideline for the Management of Glomerular Diseases (ANCA-associated vasculitis section). Kidney Int. 2021;100(4S):S1–S276.
