# Travis criteria for severe ulcerative colitis

Travis criteria

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

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

## What it computes

Apply the Travis 1996 day-3 of intravenous corticosteroids rule for severe ulcerative colitis and return travis_high from stools_per_day and crp_mg_l.

## When to use

When an agent already has the day-3 stool count and CRP in mg/L during intravenous steroid treatment for severe ulcerative colitis and needs the published Travis 1996 high-risk classification. magent does not count stools or measure CRP.

## When not to use

- Not a medical device.
- Not a colectomy order. magent does not assign surgery or return a colectomy probability.
- This is Travis 1996 day-3 of intravenous steroids for severe ulcerative colitis only. Not the Ho score. Not Truelove and Witts.
- The caller assigns stools_per_day and crp_mg_l. magent does not count stools or measure CRP.

## Formula

```
travis_high iff stools_per_day > 8 or (stools_per_day in 3-8 inclusive and crp_mg_l > 45) (Travis 1996 day-3 of IV steroids for severe UC)
```

## Citation

[Predicting outcome in severe ulcerative colitis](https://doi.org/10.1136/gut.38.6.905)
Travis SPL, Farrant JM, Ricketts C, Nolan DJ, Mortensen NM, Kettlewell MGW, Jewell DP
Gut. 1996;38(6):905-910
DOI: [10.1136/gut.38.6.905](https://doi.org/10.1136/gut.38.6.905)

## Worked example

### Nine stools on day 3

Given: `crp_mg_l=10, stools_per_day=9`

1. stools_per_day is 9 (greater than 8; stools-only arm)
2. crp_mg_l is 10 (unused on the stools-only arm)
3. travis_high is true


### Eight stools with CRP 45 mg/L

Given: `crp_mg_l=45, stools_per_day=8`

1. stools_per_day is 8 (not > 8; stools-only arm is not met)
2. stools 8 is in the 3-8 arm, but crp_mg_l is 45 (must be > 45)
3. travis_high is false


## Also searched as

- Travis criteria
- Travis 1996
- day-3 IV steroids UC
- severe ulcerative colitis Travis
- Travis CRP stools
- Travis index ulcerative colitis
- Oxford day-3 criteria
- Travis simple criteria

## Parameters

- `stools_per_day` (integer, required): Number of stools (motions) per day as assigned by the caller (integer 0-40). Travis 1996 high is stools_per_day > 8, or stools_per_day 3 to 8 inclusive with CRP > 45 mg/L. Both parameters are required. magent does not count stools.
- `crp_mg_l` (number, required): C-reactive protein in mg/L (0-500), not mg/dL. Travis 1996 CRP arm is crp_mg_l > 45 when stools_per_day is 3 to 8 inclusive. CRP = 45 is not high on that arm. magent does not assay CRP.

## 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/travis`
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": [
    {
      "crp_mg_l": "10",
      "stools_per_day": "9"
    },
    {
      "crp_mg_l": "10",
      "stools_per_day": "9"
    }
  ]
}
```

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

Example 200:

```json
{
  "count": 2,
  "path": "/api/calc/travis",
  "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": "Travis SPL, Farrant JM, Ricketts C, Nolan DJ, Mortensen NM, Kettlewell MGW, Jewell DP",
        "doi": "10.1136/gut.38.6.905",
        "id": "travis-1996",
        "pmid": "8984031",
        "source": "Gut. 1996;38(6):905-910",
        "title": "Predicting outcome in severe ulcerative colitis"
      },
      "formula": "travis",
      "formula_expression": "travis_high iff stools_per_day > 8 or (stools_per_day in 3-8 inclusive and crp_mg_l > 45) (Travis 1996 day-3 of IV steroids for severe UC)",
      "crp_mg_l": 10.0,
      "criteria": [
        {
          "value": 9,
          "factor": "stools_gt_8",
          "met": true
        },
        {
          "factor": "stools_3_to_8_and_crp_gt_45",
          "crp_mg_l": 10.0,
          "met": false,
          "stools_per_day": 9
        }
      ],
      "stools_per_day": 9,
      "travis_high": true
    },
    {
      "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": "Travis SPL, Farrant JM, Ricketts C, Nolan DJ, Mortensen NM, Kettlewell MGW, Jewell DP",
        "doi": "10.1136/gut.38.6.905",
        "id": "travis-1996",
        "pmid": "8984031",
        "source": "Gut. 1996;38(6):905-910",
        "title": "Predicting outcome in severe ulcerative colitis"
      },
      "formula": "travis",
      "formula_expression": "travis_high iff stools_per_day > 8 or (stools_per_day in 3-8 inclusive and crp_mg_l > 45) (Travis 1996 day-3 of IV steroids for severe UC)",
      "crp_mg_l": 10.0,
      "criteria": [
        {
          "value": 9,
          "factor": "stools_gt_8",
          "met": true
        },
        {
          "factor": "stools_3_to_8_and_crp_gt_45",
          "crp_mg_l": 10.0,
          "met": false,
          "stools_per_day": 9
        }
      ],
      "stools_per_day": 9,
      "travis_high": true
    }
  ]
}
```

## Response fields

- `formula` (string): travis
- `formula_expression` (string): Travis 1996 day-3 IV steroid high-risk rule for severe UC
- `travis_high` (boolean): true when stools_per_day > 8 or (stools_per_day 3-8 inclusive and crp_mg_l > 45). Not a colectomy order.
- `stools_per_day` (integer): Echo of the caller-assigned stool count (0-40)
- `crp_mg_l` (number): C-reactive protein used in mg/L
- `criteria` (array): Per-factor rows with factor and met; stools_gt_8 (value is stools) and stools_3_to_8_and_crp_gt_45. travis_high is true if either is met.
- `citation` (object): Travis 1996 Gut citation
- `disclaimer` (string): Not-a-device notice

## Example JSON

Frozen fixture. Not a live lookup.

```json
{
  "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": "Travis SPL, Farrant JM, Ricketts C, Nolan DJ, Mortensen NM, Kettlewell MGW, Jewell DP",
    "doi": "10.1136/gut.38.6.905",
    "id": "travis-1996",
    "pmid": "8984031",
    "source": "Gut. 1996;38(6):905-910",
    "title": "Predicting outcome in severe ulcerative colitis"
  },
  "formula": "travis",
  "formula_expression": "travis_high iff stools_per_day > 8 or (stools_per_day in 3-8 inclusive and crp_mg_l > 45) (Travis 1996 day-3 of IV steroids for severe UC)",
  "crp_mg_l": 10.0,
  "criteria": [
    {
      "value": 9,
      "factor": "stools_gt_8",
      "met": true
    },
    {
      "factor": "stools_3_to_8_and_crp_gt_45",
      "crp_mg_l": 10.0,
      "met": false,
      "stools_per_day": 9
    }
  ],
  "stools_per_day": 9,
  "travis_high": true
}
```

## Errors

- HTTP 400 `invalid_stools_per_day`: stools_per_day must be an integer from 0 to 40. Returned before settlement; you are not charged.
- HTTP 400 `invalid_crp`: crp_mg_l must be a number from 0 to 500. 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

- [Truelove and Witts](https://magentlab.com/docs/truelove-witts) — Apply the Truelove and Witts 1955 ulcerative colitis severity table and return mild, moderately_severe, or severe from stools_per_day and five caller-assigned flags.
- [Mayo DAI](https://magentlab.com/docs/mayo-uc) — Sum four caller-assigned Schroeder 1987 ulcerative colitis disease-activity index items (each integer 0-3) and return the total (max 12). Does not return later remission or activity bands.
- [PUCAI](https://magentlab.com/docs/pucai) — Sum six caller-assigned Turner 2007 PUCAI item points and return the published total (max 85) with activity band.

## 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.