# IMPEDE VTE score

IMPEDE VTE

Status: LIVE
Price: $0.005 USDC
`GET /api/calc/impede_vte`
HTML: https://magentlab.com/docs/impede-vte
Markdown: https://magentlab.com/docs/impede-vte.md

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

## What it computes

Compute the Sanfilippo 2019 IMPEDE VTE score for venous thromboembolism in multiple myeloma from caller-assigned Table 3 factors and return the published 6-month risk group.

## When to use

When an agent needs the published Sanfilippo 2019 IMPEDE VTE score for a patient with multiple myeloma and must not substitute Khorana or SAVED, invent a prophylaxis order, or assign race or ethnicity.

## When not to use

- Not a medical device.
- Not a diagnosis of VTE. magent does not diagnose venous thromboembolism.
- Not a prophylaxis order. This tool does not recommend a drug or start thromboprophylaxis.
- Not SAVED. Not Khorana. This tool is Sanfilippo 2019 Table 3 IMPEDE VTE only.
- Caller-assigned Asian/Pacific Islander as used in Sanfilippo 2019. magent does not assign race or ethnicity.
- bmi_ge_25 is a caller-assigned BMI ≥25 kg/m2 flag; magent does not compute BMI from height or weight.
- Dexamethasone high is total monthly dosing >160 mg as in Sanfilippo 2019; not the NCCN ≥480 mg definition. none is not on dexamethasone (0 points).
- Score is not clamped at zero. Risk groups are derivation 6-month cumulative incidence: ≤3 low 3.3%, 4-7 intermediate 8.3%, ≥8 high 15.2%.

## Formula

```
IMPEDE VTE (Sanfilippo 2019 Table 3) = imid (4) + bmi_ge_25 (1) + pelvic_hip_femur_fracture (4) + esa (1) + doxorubicin (3) + dexamethasone (none 0, low 2, high 4; high if total monthly dosing >160 mg) + asian_pacific_islander (-3) + vte_history (5) + tunneled_line (2) + thromboprophylaxis (none 0, prophylactic -3, therapeutic -4); unclamped; <=3 low 3.3%, 4-7 intermediate 8.3%, >=8 high 15.2%
```

## Citation

[Predicting venous thromboembolism in multiple myeloma: development and validation of the IMPEDE VTE score](https://doi.org/10.1002/ajh.25603)
Sanfilippo KM, Luo S, Wang TF, Fiala M, Schoen M, Wildes TM, Mikhael J, Kuderer NM, Calverley DC, Keller J, Thomas T, Carson KR, Gage BF
Am J Hematol. 2019;94(11):1176-1184
DOI: [10.1002/ajh.25603](https://doi.org/10.1002/ajh.25603)

## Worked example

### All factors absent

Given: `asian_pacific_islander=false, bmi_ge_25=false, dexamethasone=none, doxorubicin=false, esa=false, imid=false, pelvic_hip_femur_fracture=false, thromboprophylaxis=none, tunneled_line=false, vte_history=false`

1. All flags false; dexamethasone none; thromboprophylaxis none
2. Score = 0 (unclamped); risk low; six_month_vte_percent 3.3


### IMiD plus pelvic, hip, or femur fracture is high

Given: `asian_pacific_islander=false, bmi_ge_25=false, dexamethasone=none, doxorubicin=false, esa=false, imid=true, pelvic_hip_femur_fracture=true, thromboprophylaxis=none, tunneled_line=false, vte_history=false`

1. imid → 4; pelvic_hip_femur_fracture → 4
2. Score = 8; risk high; six_month_vte_percent 15.2


## Also searched as

- IMPEDE VTE
- IMPEDE-VTE score
- Sanfilippo myeloma VTE
- multiple myeloma VTE score
- IMiD VTE risk
- IMPEDE venous thromboembolism

## Parameters

- `imid` (boolean, required): Immunomodulatory drug (IMiD) as assigned by the caller (Sanfilippo 2019 Table 3). true or false. 4 points if true.
- `bmi_ge_25` (boolean, required): BMI ≥25 kg/m2 as assigned by the caller (Sanfilippo 2019 Table 3). true or false. magent does not compute BMI from height or weight. 1 point if true.
- `pelvic_hip_femur_fracture` (boolean, required): Pelvic, hip, or femur fracture as assigned by the caller (Sanfilippo 2019 Table 3). true or false. 4 points if true.
- `esa` (boolean, required): Erythropoiesis-stimulating agent as assigned by the caller (Sanfilippo 2019 Table 3). true or false. 1 point if true.
- `doxorubicin` (boolean, required): Doxorubicin as assigned by the caller (Sanfilippo 2019 Table 3). true or false. 3 points if true.
- `dexamethasone` (string, required): Dexamethasone as assigned by the caller (Sanfilippo 2019 Table 3). none (not on dexamethasone) scores 0; low (dexamethasone used at total monthly dosing ≤160 mg) scores 2; high (total monthly dosing >160 mg) scores 4. Not the NCCN ≥480 mg definition.
- `asian_pacific_islander` (boolean, required): Caller-assigned ethnicity/race Asian/Pacific Islander as used in Sanfilippo 2019. true or false. magent does not assign race or ethnicity. −3 if true.
- `vte_history` (boolean, required): History of VTE before multiple myeloma as assigned by the caller (Sanfilippo 2019 Table 3). true or false. 5 points if true.
- `tunneled_line` (boolean, required): Tunneled line / central venous catheter as assigned by the caller (Sanfilippo 2019 Table 3). true or false. 2 points if true.
- `thromboprophylaxis` (string, required): Existing thromboprophylaxis as assigned by the caller (Sanfilippo 2019 Table 3). Mutually exclusive. none scores 0; prophylactic (prophylactic LMWH or aspirin) scores −3; therapeutic (therapeutic LMWH or warfarin) scores −4.

## 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.

Method: `POST /api/calc/impede_vte`
Max items: 25
Price: unit_amount + extra_item_amount * (n - 1) (unit 5000 atomic, extra 2000 atomic)
Status: 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:

```json
{
  "items": [
    {
      "asian_pacific_islander": "false",
      "bmi_ge_25": "false",
      "dexamethasone": "none",
      "doxorubicin": "false",
      "esa": "false",
      "imid": "false",
      "pelvic_hip_femur_fracture": "false",
      "thromboprophylaxis": "none",
      "tunneled_line": "false",
      "vte_history": "false"
    },
    {
      "asian_pacific_islander": "false",
      "bmi_ge_25": "false",
      "dexamethasone": "none",
      "doxorubicin": "false",
      "esa": "false",
      "imid": "false",
      "pelvic_hip_femur_fracture": "false",
      "thromboprophylaxis": "none",
      "tunneled_line": "false",
      "vte_history": "false"
    }
  ]
}
```

Human paywall (two-item fixture): https://api.magentlab.com/paywall/bulk/impede-vte

Example 200:

```json
{
  "count": 2,
  "path": "/api/calc/impede_vte",
  "items": [
    {
      "components": [
        {
          "factor": "imid",
          "points": 0,
          "present": false
        },
        {
          "factor": "bmi_ge_25",
          "points": 0,
          "present": false
        },
        {
          "factor": "pelvic_hip_femur_fracture",
          "points": 0,
          "present": false
        },
        {
          "factor": "esa",
          "points": 0,
          "present": false
        },
        {
          "factor": "doxorubicin",
          "points": 0,
          "present": false
        },
        {
          "value": "none",
          "factor": "dexamethasone",
          "points": 0,
          "present": false
        },
        {
          "factor": "asian_pacific_islander",
          "points": 0,
          "present": false
        },
        {
          "factor": "vte_history",
          "points": 0,
          "present": false
        },
        {
          "factor": "tunneled_line",
          "points": 0,
          "present": false
        },
        {
          "value": "none",
          "factor": "thromboprophylaxis",
          "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": "Sanfilippo KM, Luo S, Wang TF, Fiala M, Schoen M, Wildes TM, Mikhael J, Kuderer NM, Calverley DC, Keller J, Thomas T, Carson KR, Gage BF",
        "doi": "10.1002/ajh.25603",
        "id": "sanfilippo-2019-impede",
        "pmid": "31374145",
        "source": "Am J Hematol. 2019;94(11):1176-1184",
        "title": "Predicting venous thromboembolism in multiple myeloma: development and validation of the IMPEDE VTE score"
      },
      "formula": "impede_vte",
      "formula_expression": "IMPEDE VTE (Sanfilippo 2019 Table 3) = imid (4) + bmi_ge_25 (1) + pelvic_hip_femur_fracture (4) + esa (1) + doxorubicin (3) + dexamethasone (none 0, low 2, high 4; high if total monthly dosing >160 mg) + asian_pacific_islander (-3) + vte_history (5) + tunneled_line (2) + thromboprophylaxis (none 0, prophylactic -3, therapeutic -4); unclamped; <=3 low 3.3%, 4-7 intermediate 8.3%, >=8 high 15.2%",
      "max_score": 24,
      "score": 0,
      "risk": "low",
      "asian_pacific_islander": false,
      "bmi_ge_25": false,
      "dexamethasone": "none",
      "doxorubicin": false,
      "esa": false,
      "imid": false,
      "pelvic_hip_femur_fracture": false,
      "six_month_vte_percent": 3.3,
      "thromboprophylaxis": "none",
      "tunneled_line": false,
      "vte_history": false
    },
    {
      "components": [
        {
          "factor": "imid",
          "points": 0,
          "present": false
        },
        {
          "factor": "bmi_ge_25",
          "points": 0,
          "present": false
        },
        {
          "factor": "pelvic_hip_femur_fracture",
          "points": 0,
          "present": false
        },
        {
          "factor": "esa",
          "points": 0,
          "present": false
        },
        {
          "factor": "doxorubicin",
          "points": 0,
          "present": false
        },
        {
          "value": "none",
          "factor": "dexamethasone",
          "points": 0,
          "present": false
        },
        {
          "factor": "asian_pacific_islander",
          "points": 0,
          "present": false
        },
        {
          "factor": "vte_history",
          "points": 0,
          "present": false
        },
        {
          "factor": "tunneled_line",
          "points": 0,
          "present": false
        },
        {
          "value": "none",
          "factor": "thromboprophylaxis",
          "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": "Sanfilippo KM, Luo S, Wang TF, Fiala M, Schoen M, Wildes TM, Mikhael J, Kuderer NM, Calverley DC, Keller J, Thomas T, Carson KR, Gage BF",
        "doi": "10.1002/ajh.25603",
        "id": "sanfilippo-2019-impede",
        "pmid": "31374145",
        "source": "Am J Hematol. 2019;94(11):1176-1184",
        "title": "Predicting venous thromboembolism in multiple myeloma: development and validation of the IMPEDE VTE score"
      },
      "formula": "impede_vte",
      "formula_expression": "IMPEDE VTE (Sanfilippo 2019 Table 3) = imid (4) + bmi_ge_25 (1) + pelvic_hip_femur_fracture (4) + esa (1) + doxorubicin (3) + dexamethasone (none 0, low 2, high 4; high if total monthly dosing >160 mg) + asian_pacific_islander (-3) + vte_history (5) + tunneled_line (2) + thromboprophylaxis (none 0, prophylactic -3, therapeutic -4); unclamped; <=3 low 3.3%, 4-7 intermediate 8.3%, >=8 high 15.2%",
      "max_score": 24,
      "score": 0,
      "risk": "low",
      "asian_pacific_islander": false,
      "bmi_ge_25": false,
      "dexamethasone": "none",
      "doxorubicin": false,
      "esa": false,
      "imid": false,
      "pelvic_hip_femur_fracture": false,
      "six_month_vte_percent": 3.3,
      "thromboprophylaxis": "none",
      "tunneled_line": false,
      "vte_history": false
    }
  ]
}
```

## Response fields

- `formula` (string): impede_vte
- `formula_expression` (string): Exact expression used
- `score` (integer): Sanfilippo 2019 Table 3 total. Not clamped at 0.
- `max_score` (integer): 24 (sum of positive Table 3 weights)
- `risk` (string): low when score ≤3, intermediate when 4-7, high when ≥8. Derivation-cohort 6-month groups. Not a diagnosis.
- `six_month_vte_percent` (number): Derivation 6-month cumulative incidence percent: 3.3 (low), 8.3 (intermediate), or 15.2 (high).
- `imid` (boolean): IMiD flag used
- `bmi_ge_25` (boolean): Caller-assigned BMI ≥25 flag used
- `pelvic_hip_femur_fracture` (boolean): Pelvic, hip, or femur fracture flag used
- `esa` (boolean): ESA flag used
- `doxorubicin` (boolean): Doxorubicin flag used
- `dexamethasone` (string): Dexamethasone token used: none, low, or high
- `asian_pacific_islander` (boolean): Caller-assigned Asian/Pacific Islander flag used
- `vte_history` (boolean): VTE-before-MM flag used
- `tunneled_line` (boolean): Tunneled line / CVC flag used
- `thromboprophylaxis` (string): Thromboprophylaxis token used: none, prophylactic, or therapeutic
- `components` (array): Per-factor points
- `citation` (object): Sanfilippo 2019 Am J Hematol citation
- `disclaimer` (string): Not-a-device notice

## Example JSON

Frozen fixture. Not a live lookup.

```json
{
  "components": [
    {
      "factor": "imid",
      "points": 0,
      "present": false
    },
    {
      "factor": "bmi_ge_25",
      "points": 0,
      "present": false
    },
    {
      "factor": "pelvic_hip_femur_fracture",
      "points": 0,
      "present": false
    },
    {
      "factor": "esa",
      "points": 0,
      "present": false
    },
    {
      "factor": "doxorubicin",
      "points": 0,
      "present": false
    },
    {
      "value": "none",
      "factor": "dexamethasone",
      "points": 0,
      "present": false
    },
    {
      "factor": "asian_pacific_islander",
      "points": 0,
      "present": false
    },
    {
      "factor": "vte_history",
      "points": 0,
      "present": false
    },
    {
      "factor": "tunneled_line",
      "points": 0,
      "present": false
    },
    {
      "value": "none",
      "factor": "thromboprophylaxis",
      "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": "Sanfilippo KM, Luo S, Wang TF, Fiala M, Schoen M, Wildes TM, Mikhael J, Kuderer NM, Calverley DC, Keller J, Thomas T, Carson KR, Gage BF",
    "doi": "10.1002/ajh.25603",
    "id": "sanfilippo-2019-impede",
    "pmid": "31374145",
    "source": "Am J Hematol. 2019;94(11):1176-1184",
    "title": "Predicting venous thromboembolism in multiple myeloma: development and validation of the IMPEDE VTE score"
  },
  "formula": "impede_vte",
  "formula_expression": "IMPEDE VTE (Sanfilippo 2019 Table 3) = imid (4) + bmi_ge_25 (1) + pelvic_hip_femur_fracture (4) + esa (1) + doxorubicin (3) + dexamethasone (none 0, low 2, high 4; high if total monthly dosing >160 mg) + asian_pacific_islander (-3) + vte_history (5) + tunneled_line (2) + thromboprophylaxis (none 0, prophylactic -3, therapeutic -4); unclamped; <=3 low 3.3%, 4-7 intermediate 8.3%, >=8 high 15.2%",
  "max_score": 24,
  "score": 0,
  "risk": "low",
  "asian_pacific_islander": false,
  "bmi_ge_25": false,
  "dexamethasone": "none",
  "doxorubicin": false,
  "esa": false,
  "imid": false,
  "pelvic_hip_femur_fracture": false,
  "six_month_vte_percent": 3.3,
  "thromboprophylaxis": "none",
  "tunneled_line": false,
  "vte_history": false
}
```

## Errors

- HTTP 400 `invalid_impede_vte`: IMPEDE-VTE inputs must match Sanfilippo 2019 Table 3 flags, dexamethasone none/low/high, and thromboprophylaxis none/prophylactic/therapeutic. Returned before settlement; you are not charged.
- HTTP 400 `invalid_items`: POST body must be a JSON object with only an items array Returned before settlement; you are not charged.
- HTTP 400 `invalid_item_count`: items must be an array of 1 to 25 objects Returned before settlement; you are not charged.
- HTTP 400 `invalid_item`: each items entry must be a JSON object Returned before settlement; you are not charged.

Shared HTTP 402 and 503: https://magentlab.com/docs/payments

## Related tools

- [Khorana score](https://magentlab.com/docs/khorana) — Compute the Khorana 2008 Blood predictive model for chemotherapy-associated thrombosis from caller-assigned cancer site, pre-chemotherapy labs, ESA use, and BMI ≥35.

## 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.

- GET the tool with Accept: application/json (do not send Accept: text/html unless you want the human paywall).
- HTTP 402 means you have not paid. Decode the base64 PAYMENT-REQUIRED header. HTTP 503 is not a new quote.
- Sign accepts[0] (exact, EIP-3009) with validBefore = now + maxTimeoutSeconds (600 seconds), or accepts[1] (batch-settlement deposit/voucher) on product GET. Ping and POST {items} stay exact. Magent retries transient facilitator 429/5xx before answering.
- Retry the same URL with PAYMENT-SIGNATURE (base64 JSON of accepted and payload). Magent attaches canonical extensions.bazaar on CDP verify/settle; echoing 402 bazaar is optional.
- Success is HTTP 200 JSON plus PAYMENT-RESPONSE. exact settles before the tool. batch-settlement verifies (and deposit-settles) before the tool and commits the charge after HTTP 2xx. HTTP 503: retry the same PAYMENT-SIGNATURE. Mint a new exact nonce only after a new HTTP 402.

- offered `exact` on eip155:8453: Fixed-price USDC on Base. The buyer authorizes the advertised amount (EIP-3009). magent settles before the tool runs (paymentFlow upfront). extra.assetTransferMethod=eip3009 extra.paymentFlow=upfront.
- offered `batch-settlement` on eip155:8453: Payment-channel vouchers claimed later in batches. Exact stays accepts[0]. Same-path POST {items} is still exact. extra.assetTransferMethod=eip3009 extra.paymentFlow=authorization.

- not offered `upto`: Not offered. Usage-based: buyer authorizes a ceiling, seller settles the actual amount after work. Reserved for a future metered tool. Not for current calculators or code search.

Same-path POST {items} is still scheme exact: one EIP-3009 authorization for GET unit plus $0.002 per extra item. That is not x402 batch-settlement (payment channels / vouchers).

Shared HTTP 402 and 503 table: https://magentlab.com/docs/payments

Stdio MCP (one process per host): https://magentlab.com/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.