MAGENT

ACS · LIVE

INTERCHEST clinical prediction rule

INTERCHEST

Sum the six Aerts 2017 INTERCHEST predictors and return whether CAD is considered absent (score <2) with the published binary-cutoff probabilities.

LIVE $0.005 USDC GET /api/calc/interchest

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

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

What it computes

Sum the six Aerts 2017 INTERCHEST predictors and return whether CAD is considered absent (score <2) with the published binary-cutoff probabilities.

When to use

When an agent needs the published INTERCHEST point total for primary-care chest pain and must not invent a chest exam, a HEART score, or per-point CAD percents.

When not to use

  • Not a medical device. Not a diagnosis, rule-out, or admission order.
  • Primary-care chest-pain rule only (Aerts 2017). Not HEART, not EDACS, and not the Bösner 2010 five-item primary-care CAD rule.
  • magent does not examine the chest. The five clinical flags are caller-assigned.
  • CAD is considered absent iff score <2 (Aerts cutoff). When <2, published CAD probability is 2.1% (95% CI 1.1–3.9) in the 13.2% prevalence setting; when ≥2, 43.0% (35.8–50.4). magent does not invent per-point percents.
  • Sex is required. Age ≥55 male or ≥65 female scores the age item (54 male and 64 female do not).

Formula

INTERCHEST = (age ≥55 if male or ≥65 if female) + physician_suspected_serious + history_of_cad + pain_on_exertion + pressure_quality − pain_reproducible_on_palpation; each ±1; range −1 to 5; CAD considered absent iff score <2 (Aerts 2017); CAD probability 2.1% (95% CI 1.1–3.9) when <2 and 43.0% (35.8–50.4) when ≥2 in the 13.2% prevalence setting

Citation

Title
Pooled individual patient data from five countries were used to derive a clinical prediction rule for coronary artery disease in primary care
Authors
Aerts M, Minalu G, Bösner S, Buntinx F, Burnand B, Haasenritter J, Herzig L, Knottnerus JA, Nilsson S, Renier W, Sox C, Sox H, Donner-Banzhoff N, International Working Group on Chest Pain in Primary Care (INTERCHEST)
Source
J Clin Epidemiol. 2017;81:120-128
DOI
10.1016/j.jclinepi.2016.09.011

Worked example

Age 40 female, all five clinical flags false

Given: age=40history_of_cad=falsepain_on_exertion=falsepain_reproducible_on_palpation=falsephysician_suspected_serious=falsepressure_quality=falsesex=female

  1. Female 40 is not ≥65 → 0; five flags false → 0
  2. Score = 0 (range −1 to 5); cad_absent true (score <2); CAD probability 2.1% (95% CI 1.1–3.9)

Two +1 flags (published CAD-not-absent cutoff)

Given: age=40history_of_cad=truepain_on_exertion=falsepain_reproducible_on_palpation=falsephysician_suspected_serious=truepressure_quality=falsesex=female

  1. Female 40 → 0; physician_suspected_serious → +1; history_of_cad → +1
  2. Score = 2 (range −1 to 5); cad_absent false (score ≥2); CAD probability 43.0% (35.8–50.4)

Also searched as

  • INTERCHEST
  • INTERCHEST rule
  • Aerts chest pain rule
  • primary care CAD prediction rule
  • INTERCHEST clinical prediction rule
  • Aerts 2017 CAD rule
  • chest pain primary care INTERCHEST
  • INTERCHEST coronary prediction

Try

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

/api/calc/interchest?age=40&sex=female&physician_suspected_serious=false&history_of_cad=false&pain_on_exertion=false&pressure_quality=false&pain_reproducible_on_palpation=false

Full URL: https://api.magentlab.com/api/calc/interchest?age=40&sex=female&physician_suspected_serious=false&history_of_cad=false&pain_on_exertion=false&pressure_quality=false&pain_reproducible_on_palpation=false

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/interchest?age=40&sex=female&physician_suspected_serious=false&history_of_cad=false&pain_on_exertion=false&pressure_quality=false&pain_reproducible_on_palpation=false"

Parameters

Name Type Required Description
age integer required Age in years (18-120). Combined with sex: female ≥65 or male ≥55 scores 1 (Aerts 2017). Age 54 male does not score; 55 male does. Age 64 female does not; 65 female does. magent computes this; do not send a precomputed flag.
sex string required · female, male female or male (required). Combined with age: female ≥65 or male ≥55 scores 1 (Aerts 2017).
physician_suspected_serious boolean required Physician initially suspected a serious diagnosis (Aerts 2017). true or false as assigned by the caller. magent does not examine the chest. +1 if true.
history_of_cad boolean required History of coronary artery disease (Aerts 2017). true or false as assigned by the caller. magent does not take a cardiac history. +1 if true.
pain_on_exertion boolean required Pain related to exertion (Aerts 2017). true or false as assigned by the caller. +1 if true.
pressure_quality boolean required Pain has a pressure quality (Aerts 2017). true or false as assigned by the caller. +1 if true.
pain_reproducible_on_palpation boolean required Pain reproducible on chest-wall palpation (Aerts 2017). true or false as assigned by the caller. magent does not examine the chest. −1 if true.

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/interchest 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": "40",
      "history_of_cad": "false",
      "pain_on_exertion": "false",
      "pain_reproducible_on_palpation": "false",
      "physician_suspected_serious": "false",
      "pressure_quality": "false",
      "sex": "female"
    },
    {
      "age": "40",
      "history_of_cad": "false",
      "pain_on_exertion": "false",
      "pain_reproducible_on_palpation": "false",
      "physician_suspected_serious": "false",
      "pressure_quality": "false",
      "sex": "female"
    }
  ]
}

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/interchest",
  "items": [
    {
      "components": [
        {
          "value": 40,
          "factor": "age_sex",
          "points": 0,
          "present": false
        },
        {
          "factor": "physician_suspected_serious",
          "points": 0,
          "present": false
        },
        {
          "factor": "history_of_cad",
          "points": 0,
          "present": false
        },
        {
          "factor": "pain_on_exertion",
          "points": 0,
          "present": false
        },
        {
          "factor": "pressure_quality",
          "points": 0,
          "present": false
        },
        {
          "factor": "pain_reproducible_on_palpation",
          "points": 0,
          "present": false
        }
      ],
      "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": "Aerts M, Minalu G, Bösner S, Buntinx F, Burnand B, Haasenritter J, Herzig L, Knottnerus JA, Nilsson S, Renier W, Sox C, Sox H, Donner-Banzhoff N, International Working Group on Chest Pain in Primary Care (INTERCHEST)",
        "doi": "10.1016/j.jclinepi.2016.09.011",
        "id": "aerts-2017",
        "pmid": "27773828",
        "source": "J Clin Epidemiol. 2017;81:120-128",
        "title": "Pooled individual patient data from five countries were used to derive a clinical prediction rule for coronary artery disease in primary care"
      },
      "formula": "interchest",
      "formula_expression": "INTERCHEST = (age ≥55 if male or ≥65 if female) + physician_suspected_serious + history_of_cad + pain_on_exertion + pressure_quality − pain_reproducible_on_palpation; each ±1; range −1 to 5; CAD considered absent iff score <2 (Aerts 2017); CAD probability 2.1% (95% CI 1.1–3.9) when <2 and 43.0% (35.8–50.4) when ≥2 in the 13.2% prevalence setting",
      "max_score": 5,
      "score": 0,
      "age_years": 40,
      "sex": "female",
      "min_score": -1,
      "cad_absent": true,
      "cad_probability_ci_high_percent": 3.9,
      "cad_probability_ci_low_percent": 1.1,
      "cad_probability_percent": 2.1,
      "prevalence_setting_percent": 13.2
    },
    {
      "components": [
        {
          "value": 40,
          "factor": "age_sex",
          "points": 0,
          "present": false
        },
        {
          "factor": "physician_suspected_serious",
          "points": 0,
          "present": false
        },
        {
          "factor": "history_of_cad",
          "points": 0,
          "present": false
        },
        {
          "factor": "pain_on_exertion",
          "points": 0,
          "present": false
        },
        {
          "factor": "pressure_quality",
          "points": 0,
          "present": false
        },
        {
          "factor": "pain_reproducible_on_palpation",
          "points": 0,
          "present": false
        }
      ],
      "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": "Aerts M, Minalu G, Bösner S, Buntinx F, Burnand B, Haasenritter J, Herzig L, Knottnerus JA, Nilsson S, Renier W, Sox C, Sox H, Donner-Banzhoff N, International Working Group on Chest Pain in Primary Care (INTERCHEST)",
        "doi": "10.1016/j.jclinepi.2016.09.011",
        "id": "aerts-2017",
        "pmid": "27773828",
        "source": "J Clin Epidemiol. 2017;81:120-128",
        "title": "Pooled individual patient data from five countries were used to derive a clinical prediction rule for coronary artery disease in primary care"
      },
      "formula": "interchest",
      "formula_expression": "INTERCHEST = (age ≥55 if male or ≥65 if female) + physician_suspected_serious + history_of_cad + pain_on_exertion + pressure_quality − pain_reproducible_on_palpation; each ±1; range −1 to 5; CAD considered absent iff score <2 (Aerts 2017); CAD probability 2.1% (95% CI 1.1–3.9) when <2 and 43.0% (35.8–50.4) when ≥2 in the 13.2% prevalence setting",
      "max_score": 5,
      "score": 0,
      "age_years": 40,
      "sex": "female",
      "min_score": -1,
      "cad_absent": true,
      "cad_probability_ci_high_percent": 3.9,
      "cad_probability_ci_low_percent": 1.1,
      "cad_probability_percent": 2.1,
      "prevalence_setting_percent": 13.2
    }
  ]
}

Response

Field Type Description
formula string interchest
formula_expression string Exact expression used
score integer INTERCHEST points -1 to 5
max_score integer 5
min_score integer -1
cad_absent boolean true iff score <2 (Aerts 2017 CAD-absent cutoff). Not a diagnosis or rule-out.
cad_probability_percent number Aerts 2017 published CAD probability at the binary cutoff only: 2.1 when score <2, 43.0 when score ≥2, in the 13.2% prevalence setting
cad_probability_ci_low_percent number Lower 95% CI of that published probability: 1.1 when <2, 35.8 when ≥2
cad_probability_ci_high_percent number Upper 95% CI of that published probability: 3.9 when <2, 50.4 when ≥2
prevalence_setting_percent number Aerts 2017 pooled-data CAD prevalence setting (13.2) for those percents
sex string female or male used with age for the age/sex predictor
age_years integer Age used with sex for the age/sex predictor
components array Per-predictor points
citation object Aerts et al. J Clin Epidemiol 2017 citation
disclaimer string Not-a-device notice

Example JSON

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

{
  "components": [
    {
      "value": 40,
      "factor": "age_sex",
      "points": 0,
      "present": false
    },
    {
      "factor": "physician_suspected_serious",
      "points": 0,
      "present": false
    },
    {
      "factor": "history_of_cad",
      "points": 0,
      "present": false
    },
    {
      "factor": "pain_on_exertion",
      "points": 0,
      "present": false
    },
    {
      "factor": "pressure_quality",
      "points": 0,
      "present": false
    },
    {
      "factor": "pain_reproducible_on_palpation",
      "points": 0,
      "present": false
    }
  ],
  "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": "Aerts M, Minalu G, Bösner S, Buntinx F, Burnand B, Haasenritter J, Herzig L, Knottnerus JA, Nilsson S, Renier W, Sox C, Sox H, Donner-Banzhoff N, International Working Group on Chest Pain in Primary Care (INTERCHEST)",
    "doi": "10.1016/j.jclinepi.2016.09.011",
    "id": "aerts-2017",
    "pmid": "27773828",
    "source": "J Clin Epidemiol. 2017;81:120-128",
    "title": "Pooled individual patient data from five countries were used to derive a clinical prediction rule for coronary artery disease in primary care"
  },
  "formula": "interchest",
  "formula_expression": "INTERCHEST = (age ≥55 if male or ≥65 if female) + physician_suspected_serious + history_of_cad + pain_on_exertion + pressure_quality − pain_reproducible_on_palpation; each ±1; range −1 to 5; CAD considered absent iff score <2 (Aerts 2017); CAD probability 2.1% (95% CI 1.1–3.9) when <2 and 43.0% (35.8–50.4) when ≥2 in the 13.2% prevalence setting",
  "max_score": 5,
  "score": 0,
  "age_years": 40,
  "sex": "female",
  "min_score": -1,
  "cad_absent": true,
  "cad_probability_ci_high_percent": 3.9,
  "cad_probability_ci_low_percent": 1.1,
  "cad_probability_percent": 2.1,
  "prevalence_setting_percent": 13.2
}

Client errors (HTTP 400)

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

HTTP Code When
400 invalid_age age must be an integer from 18 to 120 Returned before settlement; you are not charged.
400 invalid_sex sex must be female or male Returned before settlement; you are not charged.
400 invalid_flag boolean clinical flags must be true or false Returned before settlement; you are not charged.
400 invalid_items POST body must be a JSON object with only an items array Returned before settlement; you are not charged.
400 invalid_item_count items must be an array of 1 to 25 objects Returned before settlement; you are not charged.
400 invalid_item each items entry must be a JSON object Returned before settlement; you are not charged.

Related tools

  • HEART score — Compute the HEART score as age points plus caller-assigned history, ECG, risk factors, and troponin (each 0-2).
  • AUB-HAS2 — Sum the six Dakik 2019 AUB-HAS2 1-point elements and return the integer score with low / intermediate / high bands.

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.