Kidney · LIVE

Kidney Failure Risk Equation

KFRE

Compute 2-year and 5-year risk of kidney failure (dialysis or preemptive transplant) from the Tangri 2011 4-variable Kidney Failure Risk Equation (age, sex, eGFR, urine ACR).

LIVE $0.005 USDC GET /api/calc/kfre

Markdown: /docs/kfre.md · Canonical: https://magentlab.com/docs/kfre

Not a medical device. Not a diagnosis, dose, or listing recommendation.

What it computes

Compute 2-year and 5-year risk of kidney failure (dialysis or preemptive transplant) from the Tangri 2011 4-variable Kidney Failure Risk Equation (age, sex, eGFR, urine ACR).

When to use

When an agent already has age, male/female, a caller-supplied eGFR, and urine ACR in mg/g and needs that paper's 4-variable 2- and 5-year risks. Not a dialysis or transplant order, not CKD-EPI, and not the 8-variable or 2016 country-recalibrated equations.

When not to use

• Not a medical device. Not a dialysis or transplant order or referral threshold. magent does not assay creatinine or ACR and does not compute CKD-EPI eGFR.
• Tangri 2011 4-variable model only (age, sex, eGFR, urine ACR). Does not ship the 8-variable model (calcium, phosphate, bicarbonate, albumin).
• Does not apply Tangri 2016 country recalibrations or North-America vs non-North-America S0 splits. No race input.
• Derivation was referred CKD stages 3-5 (eGFR about 10-59 mL/min/1.73 m2). Age 18-90 is a magent adult clamp. Caller supplies eGFR; magent does not estimate it.
• Emits 2-year and 5-year risk percents. Does not assign a named risk class; Tangri 2011 printed stage-specific NRI cutoffs, not a class field on this equation.

Formula

LP = -0.2201*(age_years/10 - 7.036) + 0.2467*(male - 0.5642) - 0.5567*(egfr_ml_min/5 - 7.222) + 0.4510*(ln(acr_mg_g) - 5.137); 2-year risk = 1 - 0.9750^exp(LP); 5-year risk = 1 - 0.9240^exp(LP); Tangri 2011 4-variable only; male is 1 if true else 0; ACR mg/g natural log; caller supplies eGFR; not 8-variable; not Tangri 2016 country S0; no race

Citation

Title

A predictive model for progression of chronic kidney disease to kidney failure

Authors

Tangri N, Stevens LA, Griffith J, Tighiouart H, Djurdjev O, Naimark D, Levin A, Levey AS

Source

JAMA. 2011;305(15):1553-1559

DOI

10.1001/jama.2011.451

Worked example

Also searched as

• Kidney Failure Risk Equation
• KFRE
• Tangri 2011 KFRE
• 4-variable KFRE
• kidney failure risk
• CKD kidney failure risk
• Tangri 4-variable

Try

Opens the live endpoint. Unpaid browser requests show the paywall; agents should send Accept: application/json.

/api/calc/kfre?age_years=55&male=true&egfr_ml_min=30&acr_mg_g=300

Full URL: https://api.magentlab.com/api/calc/kfre?age_years=55&male=true&egfr_ml_min=30&acr_mg_g=300

Call

Expect HTTP 402 until you retry with PAYMENT-SIGNATURE. Incomplete query params return HTTP 400 before any quote or charge.

curl -i -H "Accept: application/json" "https://api.magentlab.com/api/calc/kfre?age_years=55&male=true&egfr_ml_min=30&acr_mg_g=300"

Parameters

Bulk (POST)

POST the same path with a JSON items array. The first item is the GET unit; each additional item is $0.002. Invalid items return HTTP 400 before settlement.

POST /api/calc/kfre Max 25 unit_amount + extra_item_amount * (n - 1) extra $0.002 PREVIEW

• 1 to 25 items. Each item uses the same keys as the GET query parameters.
• POST of 1 item costs the same as GET. Lists longer than 25: chunk into multiple POSTs. Extra items still execute; do not pad dummy rows.
• The first invalid item fails the whole request (index in the 400 JSON). You are not charged.
• HTTP 200 is {count, path, items}. Each items[i] is the GET 200 body for that row.
• Catalog misses (empty matches, found=false) stay paid 200s inside that slot.
• x402 resource URL is this path plus n and body_sha256. Browsers that prefer text/html get the same paywall as GET; Pay retries POST with the same items.

Example request (fixture)

{
  "items": [
    {
      "acr_mg_g": "300",
      "age_years": "55",
      "egfr_ml_min": "30",
      "male": "true"
    },
    {
      "acr_mg_g": "300",
      "age_years": "55",
      "egfr_ml_min": "30",
      "male": "true"
    }
  ]
}

Open bulk paywall →

Opens a two-item fixture on the API host. Unpaid browsers get the same MetaMask paywall as GET; Pay retries POST with those items.

Example 200 (fixture)

{
  "count": 2,
  "path": "/api/calc/kfre",
  "items": [
    {
      "disclaimer": "Not a medical device. Deterministic published-formula or published-code output for autonomous agents. A licensed clinician remains responsible for patient care and billing submissions.",
      "citation": {
        "authors": "Tangri N, Stevens LA, Griffith J, Tighiouart H, Djurdjev O, Naimark D, Levin A, Levey AS",
        "doi": "10.1001/jama.2011.451",
        "id": "tangri-2011",
        "pmid": "21642682",
        "source": "JAMA. 2011;305(15):1553-1559",
        "title": "A predictive model for progression of chronic kidney disease to kidney failure"
      },
      "formula": "kfre",
      "formula_expression": "LP = -0.2201*(age_years/10 - 7.036) + 0.2467*(male - 0.5642) - 0.5567*(egfr_ml_min/5 - 7.222) + 0.4510*(ln(acr_mg_g) - 5.137); 2-year risk = 1 - 0.9750^exp(LP); 5-year risk = 1 - 0.9240^exp(LP); Tangri 2011 4-variable only; male is 1 if true else 0; ACR mg/g natural log; caller supplies eGFR; not 8-variable; not Tangri 2016 country S0; no race",
      "age_years": 55,
      "linear_predictor": 1.3815,
      "acr_mg_g": 300.0,
      "egfr_ml_min": 30.0,
      "five_year_risk_percent": 27.0,
      "male": true,
      "s0_2_year": 0.975,
      "s0_5_year": 0.924,
      "two_year_risk_percent": 9.6
    },
    {
      "disclaimer": "Not a medical device. Deterministic published-formula or published-code output for autonomous agents. A licensed clinician remains responsible for patient care and billing submissions.",
      "citation": {
        "authors": "Tangri N, Stevens LA, Griffith J, Tighiouart H, Djurdjev O, Naimark D, Levin A, Levey AS",
        "doi": "10.1001/jama.2011.451",
        "id": "tangri-2011",
        "pmid": "21642682",
        "source": "JAMA. 2011;305(15):1553-1559",
        "title": "A predictive model for progression of chronic kidney disease to kidney failure"
      },
      "formula": "kfre",
      "formula_expression": "LP = -0.2201*(age_years/10 - 7.036) + 0.2467*(male - 0.5642) - 0.5567*(egfr_ml_min/5 - 7.222) + 0.4510*(ln(acr_mg_g) - 5.137); 2-year risk = 1 - 0.9750^exp(LP); 5-year risk = 1 - 0.9240^exp(LP); Tangri 2011 4-variable only; male is 1 if true else 0; ACR mg/g natural log; caller supplies eGFR; not 8-variable; not Tangri 2016 country S0; no race",
      "age_years": 55,
      "linear_predictor": 1.3815,
      "acr_mg_g": 300.0,
      "egfr_ml_min": 30.0,
      "five_year_risk_percent": 27.0,
      "male": true,
      "s0_2_year": 0.975,
      "s0_5_year": 0.924,
      "two_year_risk_percent": 9.6
    }
  ]
}

Response

Example JSON

Machine form of the same example. Frozen fixture. Not a live lookup.

{
  "disclaimer": "Not a medical device. Deterministic published-formula or published-code output for autonomous agents. A licensed clinician remains responsible for patient care and billing submissions.",
  "citation": {
    "authors": "Tangri N, Stevens LA, Griffith J, Tighiouart H, Djurdjev O, Naimark D, Levin A, Levey AS",
    "doi": "10.1001/jama.2011.451",
    "id": "tangri-2011",
    "pmid": "21642682",
    "source": "JAMA. 2011;305(15):1553-1559",
    "title": "A predictive model for progression of chronic kidney disease to kidney failure"
  },
  "formula": "kfre",
  "formula_expression": "LP = -0.2201*(age_years/10 - 7.036) + 0.2467*(male - 0.5642) - 0.5567*(egfr_ml_min/5 - 7.222) + 0.4510*(ln(acr_mg_g) - 5.137); 2-year risk = 1 - 0.9750^exp(LP); 5-year risk = 1 - 0.9240^exp(LP); Tangri 2011 4-variable only; male is 1 if true else 0; ACR mg/g natural log; caller supplies eGFR; not 8-variable; not Tangri 2016 country S0; no race",
  "age_years": 55,
  "linear_predictor": 1.3815,
  "acr_mg_g": 300.0,
  "egfr_ml_min": 30.0,
  "five_year_risk_percent": 27.0,
  "male": true,
  "s0_2_year": 0.975,
  "s0_5_year": 0.924,
  "two_year_risk_percent": 9.6
}

Client errors (HTTP 400)

Invalid params return 400 without charge. Shared HTTP 402 and 503 meanings: Payments.

Related tools

• CKD-EPI 2021 eGFR — Compute race-free CKD-EPI 2021 creatinine eGFR in mL/min/1.73m2.
• Cockcroft–Gault CrCl — Compute Cockcroft–Gault creatinine clearance in mL/min using total body weight.

Payment

Unpaid requests return HTTP 402 even if query parameters or POST items are missing or invalid, so CDP and agents can index the path. After a PAYMENT-SIGNATURE, invalid params return HTTP 400 JSON before settlement. magent does not charge. Fix the params, then request a new 402 quote for that complete URL. Catalog misses (empty matches, found=false) are valid paid 200s. Unpaid valid requests return HTTP 402 with a base64 PAYMENT-REQUIRED header. HTTP 503 is not a new quote: retry the same PAYMENT-SIGNATURE. Full handshake and shared payment errors: Payments. Stdio MCP: /docs/mcp.

Guarantees

• HTTP 402 is unpaid, including a missing query. After PAYMENT-SIGNATURE, invalid parameters return HTTP 400 before settlement. You are not charged. HTTP 402 never includes the tool JSON.
• exact: settlement finishes before the tool (paymentFlow upfront). batch-settlement: verify/deposit before the tool; chargedCumulativeAmount commits after HTTP 2xx. Uncertain or failed settlement fails closed (HTTP 503). Retry the same PAYMENT-SIGNATURE.
• HTTP 402 is unpaid only. Do not sign a second authorization because of a 503.
• Execution is timeout-bounded and concurrency-capped.
• Calculator inputs are stored encrypted for allowlisted operators (Magent Console). They are not in public logs, SSH lookups, catalog, or rollups. Request logs store path without query.