ECG interval · LIVE

Tisdale QT prolongation risk score

Tisdale

Sum Tisdale 2013 Table 5 points for in-hospital QT prolongation risk and return the published 0-6 / 7-10 / ≥11 band.

LIVE $0.005 USDC GET /api/calc/tisdale

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

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

What it computes

Sum Tisdale 2013 Table 5 points for in-hospital QT prolongation risk and return the published 0-6 / 7-10 / ≥11 band.

When to use

When an agent needs the published Tisdale point total and must not invent a drug-stop or TdP decision from prose.

When not to use

Not a medical device.
Not a drug-stop protocol and not a TdP (torsades de pointes) diagnosis.
The caller assigns clinical flags and the QTc-prolonging drug count. magent does not interpret the ECG or identify the drugs.
Bands follow Tisdale 2013 validation (low <7, moderate 7-10, high ≥11). Table 6 “>11” is a typesetting gap; 11 is high. This tool does not return percents.

Formula

Tisdale = age≥68 1 + female 1 + loop_diuretic 1 + potassium≤3.5 2 + admission_QTc≥450 2 + acute_MI 2 + sepsis 3 + heart_failure 3 + one_QTc_prolonging_drug 3 + ≥2_QTc_prolonging_drugs 3; Table 5; max 21; bands 0-6 / 7-10 / ≥11

Citation

Title: Development and validation of a risk score to predict QT interval prolongation in hospitalized patients
Authors: Tisdale JE, Jaynes HA, Kingery JR, et al.
Source: Circ Cardiovasc Qual Outcomes. 2013;6(4):479-487
DOI: 10.1161/CIRCOUTCOMES.113.000152

Worked example

No Table 5 factors

Given: acute_mi=falseadmission_qtc_ms=400age=60heart_failure=falseloop_diuretic=falsepotassium_mmol_l=4.0qtc_prolonging_drugs=0sepsis=falsesex=male

Age 60 <68 → 0; male → 0; loop false → 0; K 4.0 >3.5 → 0; QTc 400 <450 → 0; MI/sepsis/HF false → 0; drugs 0 → 0
Score = 0 (max 21); tisdale_band 0-6

K ≤3.5, sepsis, heart failure, one QTc-prolonging drug

Given: acute_mi=falseadmission_qtc_ms=400age=60heart_failure=trueloop_diuretic=falsepotassium_mmol_l=3.5qtc_prolonging_drugs=1sepsis=truesex=male

K 3.5 → 2; sepsis → 3; heart failure → 3; one QTc-prolonging drug → 3
Score = 11 (max 21); tisdale_band >=11

Also searched as

Tisdale score
Tisdale QT risk score
QT prolongation risk score
hospital QTc risk score
Tisdale 2013
QTc prolonging drugs risk

Try

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

/api/calc/tisdale?age=60&sex=male&loop_diuretic=false&potassium_mmol_l=4.0&admission_qtc_ms=400&acute_mi=false&sepsis=false&heart_failure=false&qtc_prolonging_drugs=0

Full URL: https://api.magentlab.com/api/calc/tisdale?age=60&sex=male&loop_diuretic=false&potassium_mmol_l=4.0&admission_qtc_ms=400&acute_mi=false&sepsis=false&heart_failure=false&qtc_prolonging_drugs=0

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/tisdale?age=60&sex=male&loop_diuretic=false&potassium_mmol_l=4.0&admission_qtc_ms=400&acute_mi=false&sepsis=false&heart_failure=false&qtc_prolonging_drugs=0"

Parameters

Name	Type	Required	Description
`age`	integer	required	Age in years (18-120). Age ≥68 scores 1 (Tisdale 2013 Table 5). 67 does not score.
`sex`	string	required · female, male	female scores 1; male scores 0 (Tisdale 2013 Table 5).
`loop_diuretic`	boolean	required	Loop diuretic (Tisdale 2013 Table 5). true or false. Scores 1 if true.
`potassium_mmol_l`	number	required	Serum potassium in mmol/L (1.5-8.0). ≤3.5 scores 2 (Tisdale 2013 Table 5). 3.5 scores; 3.51 does not.
`admission_qtc_ms`	number	required	Admission QTc in milliseconds (200-800). ≥450 scores 2 (Tisdale 2013 Table 5). 450 scores.
`acute_mi`	boolean	required	Acute myocardial infarction (Tisdale 2013 Table 5). true or false. Scores 2 if true.
`sepsis`	boolean	required	Sepsis (Tisdale 2013 Table 5). true or false. Scores 3 if true.
`heart_failure`	boolean	required	Left ventricular dysfunction / heart failure (Tisdale 2013 Table 5). true or false. Scores 3 if true.
`qtc_prolonging_drugs`	integer	required	Count of QTc-prolonging drugs (integer 0-20). 0 → 0 points; 1 → 3 points; ≥2 → 6 points (Table 5 one-drug and ≥2-drug rows stack).

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/tisdale 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": [
    {
      "acute_mi": "false",
      "admission_qtc_ms": "400",
      "age": "60",
      "heart_failure": "false",
      "loop_diuretic": "false",
      "potassium_mmol_l": "4.0",
      "qtc_prolonging_drugs": "0",
      "sepsis": "false",
      "sex": "male"
    },
    {
      "acute_mi": "false",
      "admission_qtc_ms": "400",
      "age": "60",
      "heart_failure": "false",
      "loop_diuretic": "false",
      "potassium_mmol_l": "4.0",
      "qtc_prolonging_drugs": "0",
      "sepsis": "false",
      "sex": "male"
    }
  ]
}

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/tisdale",
  "items": [
    {
      "components": [
        {
          "value": 60,
          "factor": "age_ge_68",
          "points": 0,
          "present": false
        },
        {
          "factor": "female",
          "points": 0,
          "present": false
        },
        {
          "factor": "loop_diuretic",
          "points": 0,
          "present": false
        },
        {
          "value": 4.0,
          "factor": "potassium_le_3_5",
          "points": 0,
          "present": false
        },
        {
          "value": 400.0,
          "factor": "admission_qtc_ge_450",
          "points": 0,
          "present": false
        },
        {
          "factor": "acute_mi",
          "points": 0,
          "present": false
        },
        {
          "factor": "sepsis",
          "points": 0,
          "present": false
        },
        {
          "factor": "heart_failure",
          "points": 0,
          "present": false
        },
        {
          "value": 0,
          "factor": "one_qtc_prolonging_drug",
          "points": 0,
          "present": false
        },
        {
          "value": 0,
          "factor": "two_or_more_qtc_prolonging_drugs",
          "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": "Tisdale JE, Jaynes HA, Kingery JR, et al.",
        "doi": "10.1161/CIRCOUTCOMES.113.000152",
        "id": "tisdale-2013",
        "pmid": "23716032",
        "source": "Circ Cardiovasc Qual Outcomes. 2013;6(4):479-487",
        "title": "Development and validation of a risk score to predict QT interval prolongation in hospitalized patients"
      },
      "formula": "tisdale",
      "formula_expression": "Tisdale = age≥68 1 + female 1 + loop_diuretic 1 + potassium≤3.5 2 + admission_QTc≥450 2 + acute_MI 2 + sepsis 3 + heart_failure 3 + one_QTc_prolonging_drug 3 + ≥2_QTc_prolonging_drugs 3; Table 5; max 21; bands 0-6 / 7-10 / ≥11",
      "max_score": 21,
      "score": 0,
      "age_years": 60,
      "sex": "male",
      "potassium_mmol_l": 4.0,
      "admission_qtc_ms": 400.0,
      "qtc_prolonging_drugs": 0,
      "tisdale_band": "0-6"
    },
    {
      "components": [
        {
          "value": 60,
          "factor": "age_ge_68",
          "points": 0,
          "present": false
        },
        {
          "factor": "female",
          "points": 0,
          "present": false
        },
        {
          "factor": "loop_diuretic",
          "points": 0,
          "present": false
        },
        {
          "value": 4.0,
          "factor": "potassium_le_3_5",
          "points": 0,
          "present": false
        },
        {
          "value": 400.0,
          "factor": "admission_qtc_ge_450",
          "points": 0,
          "present": false
        },
        {
          "factor": "acute_mi",
          "points": 0,
          "present": false
        },
        {
          "factor": "sepsis",
          "points": 0,
          "present": false
        },
        {
          "factor": "heart_failure",
          "points": 0,
          "present": false
        },
        {
          "value": 0,
          "factor": "one_qtc_prolonging_drug",
          "points": 0,
          "present": false
        },
        {
          "value": 0,
          "factor": "two_or_more_qtc_prolonging_drugs",
          "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": "Tisdale JE, Jaynes HA, Kingery JR, et al.",
        "doi": "10.1161/CIRCOUTCOMES.113.000152",
        "id": "tisdale-2013",
        "pmid": "23716032",
        "source": "Circ Cardiovasc Qual Outcomes. 2013;6(4):479-487",
        "title": "Development and validation of a risk score to predict QT interval prolongation in hospitalized patients"
      },
      "formula": "tisdale",
      "formula_expression": "Tisdale = age≥68 1 + female 1 + loop_diuretic 1 + potassium≤3.5 2 + admission_QTc≥450 2 + acute_MI 2 + sepsis 3 + heart_failure 3 + one_QTc_prolonging_drug 3 + ≥2_QTc_prolonging_drugs 3; Table 5; max 21; bands 0-6 / 7-10 / ≥11",
      "max_score": 21,
      "score": 0,
      "age_years": 60,
      "sex": "male",
      "potassium_mmol_l": 4.0,
      "admission_qtc_ms": 400.0,
      "qtc_prolonging_drugs": 0,
      "tisdale_band": "0-6"
    }
  ]
}

Response

Field	Type	Description
`formula`	string	tisdale
`formula_expression`	string	Exact expression used
`score`	integer	Tisdale 2013 Table 5 points 0-21
`max_score`	integer	21
`tisdale_band`	string	Validation band: 0-6 (low, score <7), 7-10 (moderate), or >=11 (high). Score 11 is high. Not a percent.
`age_years`	integer	Age used for the ≥68 point
`sex`	string	female or male
`potassium_mmol_l`	number	Serum potassium in mmol/L
`admission_qtc_ms`	number	Admission QTc in ms
`qtc_prolonging_drugs`	integer	Caller-assigned QTc-prolonging drug count 0-20
`components`	array	Per-factor points (Table 5 rows, including stacked drug rows)
`citation`	object	Tisdale et al. Circ Cardiovasc Qual Outcomes 2013 citation
`disclaimer`	string	Not-a-device notice

Example JSON

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

{
  "components": [
    {
      "value": 60,
      "factor": "age_ge_68",
      "points": 0,
      "present": false
    },
    {
      "factor": "female",
      "points": 0,
      "present": false
    },
    {
      "factor": "loop_diuretic",
      "points": 0,
      "present": false
    },
    {
      "value": 4.0,
      "factor": "potassium_le_3_5",
      "points": 0,
      "present": false
    },
    {
      "value": 400.0,
      "factor": "admission_qtc_ge_450",
      "points": 0,
      "present": false
    },
    {
      "factor": "acute_mi",
      "points": 0,
      "present": false
    },
    {
      "factor": "sepsis",
      "points": 0,
      "present": false
    },
    {
      "factor": "heart_failure",
      "points": 0,
      "present": false
    },
    {
      "value": 0,
      "factor": "one_qtc_prolonging_drug",
      "points": 0,
      "present": false
    },
    {
      "value": 0,
      "factor": "two_or_more_qtc_prolonging_drugs",
      "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": "Tisdale JE, Jaynes HA, Kingery JR, et al.",
    "doi": "10.1161/CIRCOUTCOMES.113.000152",
    "id": "tisdale-2013",
    "pmid": "23716032",
    "source": "Circ Cardiovasc Qual Outcomes. 2013;6(4):479-487",
    "title": "Development and validation of a risk score to predict QT interval prolongation in hospitalized patients"
  },
  "formula": "tisdale",
  "formula_expression": "Tisdale = age≥68 1 + female 1 + loop_diuretic 1 + potassium≤3.5 2 + admission_QTc≥450 2 + acute_MI 2 + sepsis 3 + heart_failure 3 + one_QTc_prolonging_drug 3 + ≥2_QTc_prolonging_drugs 3; Table 5; max 21; bands 0-6 / 7-10 / ≥11",
  "max_score": 21,
  "score": 0,
  "age_years": 60,
  "sex": "male",
  "potassium_mmol_l": 4.0,
  "admission_qtc_ms": 400.0,
  "qtc_prolonging_drugs": 0,
  "tisdale_band": "0-6"
}

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_potassium`	potassium_mmol_l must be a number from 1.5 to 8.0. Returned before settlement; you are not charged.
400	`invalid_admission_qtc`	admission_qtc_ms must be a number from 200 to 800 (Tisdale 2013). Returned before settlement; you are not charged.
400	`invalid_qtc_drug_count`	qtc_prolonging_drugs must be an integer from 0 to 20 (Tisdale 2013). 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

QTc — Compute heart-rate-corrected QT using Bazett or Fridericia. The formula argument is required.

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.
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.