Hemodynamics · LIVE

Steinhart AHF probability (2009)

Steinhart AHF

Compute the Steinhart 2009 Equation 1 probability of acute heart failure from caller-assigned age, clinician pretest probability, and NT-proBNP in pg/mL.

LIVE $0.005 USDC GET /api/calc/steinhart

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

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

What it computes

Compute the Steinhart 2009 Equation 1 probability of acute heart failure from caller-assigned age, clinician pretest probability, and NT-proBNP in pg/mL.

When to use

When an agent has Steinhart 2009 age, clinician pretest probability, and NT-proBNP in pg/mL and needs Equation 1 Pr(AHF) from the unrounded probability plus the published ≤0.20 and ≥0.80 flags, not a diuretic or admission order.

When not to use

• Not a medical device. Not a diagnosis. Not a diuretic order or an admission order. magent does not assay NT-proBNP or assign pretest probability.
• Steinhart 2009 Equation 1 only. NT-proBNP is pg/mL, not pmol/L. magent does not convert units.
• pretest_probability is caller-assigned as a fraction 0-1; values above 1 through 100 are treated as percent. magent does not examine the patient.
• ahf_le_0_20 and ahf_ge_0_80 are the published model treatment thresholds (Pr(AHF) ≤0.20 and ≥0.80). magent does not invent intermediate bands.
• estimated_probability_percent is a population probability from the unrounded Equation 1 value, not an individual outcome.

Formula

Pr(AHF) = 1 / (1 + exp(1.801 - 0.011*age - 5.914*pretest - 0.822*log10(nt_probnp_pg_ml))); pretest is clinician pretest probability as a fraction 0-1 (0-100 percent is divided by 100); NT-proBNP is pg/mL; logit = -(1.801 - 0.011*age - 5.914*pretest - 0.822*log10(nt_probnp_pg_ml)), 2 decimals; estimated_probability_percent = 100 * Pr(AHF) from the unrounded probability, 2 decimals; ahf_le_0_20 is true when Pr(AHF) <= 0.20; ahf_ge_0_80 is true when Pr(AHF) >= 0.80 (Steinhart 2009)

Citation

Title

Improving the Diagnosis of Acute Heart Failure Using a Validated Prediction Model

Authors

Steinhart B, Thorpe KE, Bayoumi AM, Moe G, Januzzi JL Jr, Mazer CD

Source

J Am Coll Cardiol. 2009;54(16):1515-1521

DOI

10.1016/j.jacc.2009.05.065

Worked example

Also searched as

• Steinhart AHF model
• Steinhart NT-proBNP probability
• acute heart failure undifferentiated dyspnea
• clinician pretest NT-proBNP AHF
• Steinhart 2009 JACC AHF
• post-test probability acute heart failure
• NT-proBNP age pretest AHF

Try

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

/api/calc/steinhart?age=70&pretest_probability=0.50&nt_probnp_pg_ml=1000

Full URL: https://api.magentlab.com/api/calc/steinhart?age=70&pretest_probability=0.50&nt_probnp_pg_ml=1000

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/steinhart?age=70&pretest_probability=0.50&nt_probnp_pg_ml=1000"

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/steinhart 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": [
    {
      "age": "70",
      "nt_probnp_pg_ml": "1000",
      "pretest_probability": "0.50"
    },
    {
      "age": "70",
      "nt_probnp_pg_ml": "1000",
      "pretest_probability": "0.50"
    }
  ]
}

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/steinhart",
  "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": "Steinhart B, Thorpe KE, Bayoumi AM, Moe G, Januzzi JL Jr, Mazer CD",
        "doi": "10.1016/j.jacc.2009.05.065",
        "id": "steinhart-2009",
        "pmid": "19815125",
        "source": "J Am Coll Cardiol. 2009;54(16):1515-1521",
        "title": "Improving the Diagnosis of Acute Heart Failure Using a Validated Prediction Model"
      },
      "formula": "steinhart",
      "formula_expression": "Pr(AHF) = 1 / (1 + exp(1.801 - 0.011*age - 5.914*pretest - 0.822*log10(nt_probnp_pg_ml))); pretest is clinician pretest probability as a fraction 0-1 (0-100 percent is divided by 100); NT-proBNP is pg/mL; logit = -(1.801 - 0.011*age - 5.914*pretest - 0.822*log10(nt_probnp_pg_ml)), 2 decimals; estimated_probability_percent = 100 * Pr(AHF) from the unrounded probability, 2 decimals; ahf_le_0_20 is true when Pr(AHF) <= 0.20; ahf_ge_0_80 is true when Pr(AHF) >= 0.80 (Steinhart 2009)",
      "age_years": 70,
      "estimated_probability_percent": 98.78,
      "logit": 4.39,
      "ahf_ge_0_80": true,
      "ahf_le_0_20": false,
      "nt_probnp_pg_ml": 1.0e3,
      "pretest_probability": 0.5
    },
    {
      "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": "Steinhart B, Thorpe KE, Bayoumi AM, Moe G, Januzzi JL Jr, Mazer CD",
        "doi": "10.1016/j.jacc.2009.05.065",
        "id": "steinhart-2009",
        "pmid": "19815125",
        "source": "J Am Coll Cardiol. 2009;54(16):1515-1521",
        "title": "Improving the Diagnosis of Acute Heart Failure Using a Validated Prediction Model"
      },
      "formula": "steinhart",
      "formula_expression": "Pr(AHF) = 1 / (1 + exp(1.801 - 0.011*age - 5.914*pretest - 0.822*log10(nt_probnp_pg_ml))); pretest is clinician pretest probability as a fraction 0-1 (0-100 percent is divided by 100); NT-proBNP is pg/mL; logit = -(1.801 - 0.011*age - 5.914*pretest - 0.822*log10(nt_probnp_pg_ml)), 2 decimals; estimated_probability_percent = 100 * Pr(AHF) from the unrounded probability, 2 decimals; ahf_le_0_20 is true when Pr(AHF) <= 0.20; ahf_ge_0_80 is true when Pr(AHF) >= 0.80 (Steinhart 2009)",
      "age_years": 70,
      "estimated_probability_percent": 98.78,
      "logit": 4.39,
      "ahf_ge_0_80": true,
      "ahf_le_0_20": false,
      "nt_probnp_pg_ml": 1.0e3,
      "pretest_probability": 0.5
    }
  ]
}

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": "Steinhart B, Thorpe KE, Bayoumi AM, Moe G, Januzzi JL Jr, Mazer CD",
    "doi": "10.1016/j.jacc.2009.05.065",
    "id": "steinhart-2009",
    "pmid": "19815125",
    "source": "J Am Coll Cardiol. 2009;54(16):1515-1521",
    "title": "Improving the Diagnosis of Acute Heart Failure Using a Validated Prediction Model"
  },
  "formula": "steinhart",
  "formula_expression": "Pr(AHF) = 1 / (1 + exp(1.801 - 0.011*age - 5.914*pretest - 0.822*log10(nt_probnp_pg_ml))); pretest is clinician pretest probability as a fraction 0-1 (0-100 percent is divided by 100); NT-proBNP is pg/mL; logit = -(1.801 - 0.011*age - 5.914*pretest - 0.822*log10(nt_probnp_pg_ml)), 2 decimals; estimated_probability_percent = 100 * Pr(AHF) from the unrounded probability, 2 decimals; ahf_le_0_20 is true when Pr(AHF) <= 0.20; ahf_ge_0_80 is true when Pr(AHF) >= 0.80 (Steinhart 2009)",
  "age_years": 70,
  "estimated_probability_percent": 98.78,
  "logit": 4.39,
  "ahf_ge_0_80": true,
  "ahf_le_0_20": false,
  "nt_probnp_pg_ml": 1.0e3,
  "pretest_probability": 0.5
}

Client errors (HTTP 400)

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

Related tools

• H2FPEF — Sum the Reddy 2018 H2FPEF points score (six components, max 9) and return score and max_score only.
• ADHERE — Apply the Fonarow 2005 ADHERE classification and regression tree for in-hospital mortality risk in acutely decompensated heart failure from admission BUN, systolic blood pressure, and serum creatinine.

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.