# TRISS (Boyd 1987)

TRISS

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

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

## What it computes

Compute Boyd 1987 TRISS probability of survival from mechanism, Champion weighted RTS, ISS, and age using the original Major Trauma Outcome Study coefficients printed with that method.

## When to use

When an agent needs the published Boyd 1987 TRISS probability of survival and must not recode GCS/SBP/RR, substitute NISS or ASCOT, or apply Champion 1995 revised coefficients.

## When not to use

- Not a medical device. Not a triage order, trauma-activation, or disposition.
- RTS is a caller-assigned Champion weighted Revised Trauma Score (0.0-7.8408). magent does not recode GCS, SBP, or respiratory rate here.
- ISS is a caller-assigned Baker total (1-75). This tool does not compute ISS from AIS, NISS, or ASCOT.
- Boyd 1987 original MTOS coefficients only. Champion 1995 revised TRISS coefficients are not this tool.
- AgeIndex is 0 if age < 55 and 1 if age >= 55 as published. magent does not use continuous age.

## Formula

```
Ps = 1 / (1 + e^(-b)); AgeIndex = 0 if age < 55 else 1; blunt: b = -1.2470 + 0.9544*RTS - 0.0768*ISS - 1.9052*AgeIndex; penetrating: b = -0.6029 + 1.1430*RTS - 0.1516*ISS - 2.6676*AgeIndex (Boyd 1987 original MTOS)
```

## Citation

[Evaluating trauma care: the TRISS method. Trauma Score and the Injury Severity Score](https://doi.org/10.1097/00005373-198704000-00005)
Boyd CR, Tolson MA, Copes WS
J Trauma. 1987;27(4):370-378
DOI: [10.1097/00005373-198704000-00005](https://doi.org/10.1097/00005373-198704000-00005)

## Worked example

### Blunt, RTS 7.8408, ISS 9, age 30

Given: `age=30, iss=9, mechanism=blunt, rts=7.8408`

1. Age 30 → AgeIndex 0 (age < 55)
2. blunt: b = -1.2470 + 0.9544*7.8408 - 0.0768*9 - 1.9052*0 = 5.5451
3. Ps = 1 / (1 + e^(-b)) = 0.9961


### Blunt, RTS 7.8408, ISS 9, age 55

Given: `age=55, iss=9, mechanism=blunt, rts=7.8408`

1. Age 55 → AgeIndex 1
2. blunt: b = -1.2470 + 0.9544*7.8408 - 0.0768*9 - 1.9052*1 = 3.6399
3. Ps = 1 / (1 + e^(-b)) = 0.9744


## Also searched as

- trauma injury severity score
- TRISS probability of survival
- Boyd TRISS MTOS
- blunt penetrating trauma survival
- RTS ISS AgeIndex
- original MTOS TRISS

## Parameters

- `mechanism` (string, required): blunt or penetrating. Selects the Boyd 1987 original MTOS coefficient set. Required; magent does not infer mechanism.
- `rts` (number, required): Caller-assigned Champion weighted Revised Trauma Score (number 0.0-7.8408). magent does not recode GCS, SBP, or respiratory rate here.
- `iss` (integer, required): Caller-assigned Injury Severity Score integer 1-75. magent does not compute ISS from AIS here.
- `age` (integer, required): Age in whole years 1-120. AgeIndex is 0 if age < 55 and 1 if age >= 55 (Boyd 1987).

## 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/triss`
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": [
    {
      "age": "30",
      "iss": "9",
      "mechanism": "blunt",
      "rts": "7.8408"
    },
    {
      "age": "30",
      "iss": "9",
      "mechanism": "blunt",
      "rts": "7.8408"
    }
  ]
}
```

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

Example 200:

```json
{
  "count": 2,
  "path": "/api/calc/triss",
  "items": [
    {
      "b": 5.5451,
      "age": 30,
      "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": "Boyd CR, Tolson MA, Copes WS",
        "doi": "10.1097/00005373-198704000-00005",
        "id": "boyd-1987",
        "pmid": "3106646",
        "source": "J Trauma. 1987;27(4):370-378",
        "title": "Evaluating trauma care: the TRISS method. Trauma Score and the Injury Severity Score"
      },
      "formula": "triss",
      "formula_expression": "Ps = 1 / (1 + e^(-b)); AgeIndex = 0 if age < 55 else 1; blunt: b = -1.2470 + 0.9544*RTS - 0.0768*ISS - 1.9052*AgeIndex; penetrating: b = -0.6029 + 1.1430*RTS - 0.1516*ISS - 2.6676*AgeIndex (Boyd 1987 original MTOS)",
      "mechanism": "blunt",
      "rts": 7.8408,
      "age_index": 0,
      "iss": 9,
      "survival_probability": 0.9961
    },
    {
      "b": 5.5451,
      "age": 30,
      "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": "Boyd CR, Tolson MA, Copes WS",
        "doi": "10.1097/00005373-198704000-00005",
        "id": "boyd-1987",
        "pmid": "3106646",
        "source": "J Trauma. 1987;27(4):370-378",
        "title": "Evaluating trauma care: the TRISS method. Trauma Score and the Injury Severity Score"
      },
      "formula": "triss",
      "formula_expression": "Ps = 1 / (1 + e^(-b)); AgeIndex = 0 if age < 55 else 1; blunt: b = -1.2470 + 0.9544*RTS - 0.0768*ISS - 1.9052*AgeIndex; penetrating: b = -0.6029 + 1.1430*RTS - 0.1516*ISS - 2.6676*AgeIndex (Boyd 1987 original MTOS)",
      "mechanism": "blunt",
      "rts": 7.8408,
      "age_index": 0,
      "iss": 9,
      "survival_probability": 0.9961
    }
  ]
}
```

## Response fields

- `formula` (string): triss
- `formula_expression` (string): Boyd 1987 original MTOS TRISS equations
- `mechanism` (string): blunt or penetrating
- `rts` (number): Caller-assigned weighted RTS
- `iss` (integer): Caller-assigned ISS 1-75
- `age` (integer): Caller age in years 1-120
- `age_index` (integer): 0 if age < 55 else 1
- `b` (number): TRISS logit b, 4 decimal places
- `survival_probability` (number): Ps = 1 / (1 + e^(-b)), 4 decimal places
- `citation` (object): Boyd 1987 citation
- `disclaimer` (string): Not a medical device

## Example JSON

Frozen fixture. Not a live lookup.

```json
{
  "b": 5.5451,
  "age": 30,
  "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": "Boyd CR, Tolson MA, Copes WS",
    "doi": "10.1097/00005373-198704000-00005",
    "id": "boyd-1987",
    "pmid": "3106646",
    "source": "J Trauma. 1987;27(4):370-378",
    "title": "Evaluating trauma care: the TRISS method. Trauma Score and the Injury Severity Score"
  },
  "formula": "triss",
  "formula_expression": "Ps = 1 / (1 + e^(-b)); AgeIndex = 0 if age < 55 else 1; blunt: b = -1.2470 + 0.9544*RTS - 0.0768*ISS - 1.9052*AgeIndex; penetrating: b = -0.6029 + 1.1430*RTS - 0.1516*ISS - 2.6676*AgeIndex (Boyd 1987 original MTOS)",
  "mechanism": "blunt",
  "rts": 7.8408,
  "age_index": 0,
  "iss": 9,
  "survival_probability": 0.9961
}
```

## Errors

- HTTP 400 `invalid_triss_mechanism`: mechanism must be blunt or penetrating (Boyd 1987 TRISS). Returned before settlement; you are not charged.
- HTTP 400 `invalid_rts_value`: rts must be a number from 0.0 to 7.8408 (Champion weighted RTS for TRISS). Returned before settlement; you are not charged.
- HTTP 400 `invalid_iss_total`: iss must be an integer from 1 to 75 (Boyd 1987 TRISS). Returned before settlement; you are not charged.
- HTTP 400 `invalid_triss_age`: age must be an integer from 1 to 120 (Boyd 1987 TRISS AgeIndex). 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

- [RTS](https://magentlab.com/docs/rts) — Compute Champion 1989 coded GCS, SBP, and respiratory-rate values, the triage T-RTS sum, and the weighted RTS used for outcome evaluation.
- [ISS](https://magentlab.com/docs/iss) — Compute the Baker 1974 Injury Severity Score as the sum of squares of the three highest caller-assigned AIS body-region grades, or 75 if any region is AIS 6.

## 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.