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Ho index for severe ulcerative colitis

Ho index

Sum the Ho 2004 day-3 IV-steroid score for severe ulcerative colitis from mean stool frequency, colonic dilatation, and hypoalbuminaemia, and return the published medical-therapy failure bands.

LIVE $0.005 USDC GET /api/calc/ho_index

Markdown: /docs/ho-index.md · Canonical: https://magentlab.com/docs/ho-index

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

What it computes

Sum the Ho 2004 day-3 IV-steroid score for severe ulcerative colitis from mean stool frequency, colonic dilatation, and hypoalbuminaemia, and return the published medical-therapy failure bands.

When to use

When an agent already has the first-three-day mean stool frequency, a caller-assigned colonic-dilatation flag, and albumin during intravenous steroid treatment for severe ulcerative colitis and needs the published Ho 2004 point total and medical-therapy failure bands. magent does not count stools, read films, or measure albumin.

When not to use

Not a medical device.
Not a colectomy order, second-line medical-therapy order, or surgery assignment. magent does not assign treatment.
This is Ho 2004 day-3 of intravenous steroids for severe ulcerative colitis only. Not Travis (day-3 stool count + CRP). Not Truelove and Witts.
The caller assigns mean_stool_frequency, colonic_dilatation, and albumin. magent does not count stools, read an abdominal film, or measure albumin. colonic_dilatation has no centimetre cutoff in this tool.
Equality at 30 g/L is not hypoalbuminaemia.

Formula

Ho 2004 day-3 IV-steroid severe UC: stool_points(<4 → 0; 4 ≤ mean_stool_frequency < 6 → 1; 6 ≤ x ≤ 9 → 2; x > 9 → 4) + colonic_dilatation (true → 4) + hypoalbuminaemia (albumin_g_l < 30 → 1); max 9; medical-therapy failure 0–1 → 11%, 2–3 → 43%, ≥4 → 85% (ROC operating point ≥4)

Citation

Title: Predicting the outcome of severe ulcerative colitis: development of a novel risk score to aid early selection of patients for second-line medical therapy or surgery
Authors: Ho GT, Mowat C, Goddard CJ, Fennell JM, Shah NB, Prescott RJ, Satsangi J
Source: Aliment Pharmacol Ther. 2004;19(10):1079-1087
DOI: 10.1111/j.1365-2036.2004.01945.x

Worked example

Mean stools 3, no dilatation, albumin 35 g/L

Given: albumin_g_l=35colonic_dilatation=falsemean_stool_frequency=3

mean_stool_frequency 3 is < 4 → 0 points
colonic_dilatation is false → 0 points
albumin 35 g/L is not < 30 → 0 points
score = 0 (low; medical-therapy failure 11%)

Mean stools 3 with colonic dilatation

Given: albumin_g_l=35colonic_dilatation=truemean_stool_frequency=3

mean_stool_frequency 3 is < 4 → 0 points
colonic_dilatation is true → 4 points
albumin 35 g/L is not < 30 → 0 points
score = 4 (high; medical-therapy failure 85%; ROC operating point)

Also searched as

Ho index
Ho score
Ho 2004 UC
day-3 severe UC score
Ho ulcerative colitis
Ho IV steroid UC
Ho risk score UC
severe UC Ho index

Try

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

/api/calc/ho_index?mean_stool_frequency=3&colonic_dilatation=false&albumin_g_l=35

Full URL: https://api.magentlab.com/api/calc/ho_index?mean_stool_frequency=3&colonic_dilatation=false&albumin_g_l=35

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/ho_index?mean_stool_frequency=3&colonic_dilatation=false&albumin_g_l=35"

Parameters

Name	Type	Required	Description
`mean_stool_frequency`	number	required	Mean stool frequency over the first 3 days of IV steroids, as assigned by the caller (number 0-40). Ho 2004: <4 scores 0; 4 ≤ x < 6 scores 1; 6 ≤ x ≤ 9 scores 2; x > 9 scores 4. Exactly 6 and exactly 9 score 2. magent does not count stools.
`colonic_dilatation`	boolean	required	Caller-assigned colonic dilatation (Ho 2004). true scores 4; false scores 0. magent does not read an abdominal film and does not invent a centimetre cutoff.
`albumin_g_l`	number	optional	Serum albumin in g/L (10-60). Provide this or albumin_g_dl, not both. Ho 2004 hypoalbuminaemia is <30 g/L (30 is not low). magent does not assay albumin.
`albumin_g_dl`	number	optional	Serum albumin in g/dL (1-6). Converted as g/L = g/dL × 10. Provide this or albumin_g_l, not both.

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/ho_index 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": [
    {
      "albumin_g_l": "35",
      "colonic_dilatation": "false",
      "mean_stool_frequency": "3"
    },
    {
      "albumin_g_l": "35",
      "colonic_dilatation": "false",
      "mean_stool_frequency": "3"
    }
  ]
}

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/ho_index",
  "items": [
    {
      "components": [
        {
          "value": 3.0,
          "factor": "mean_stool_frequency",
          "points": 0,
          "present": false
        },
        {
          "factor": "colonic_dilatation",
          "points": 0,
          "present": false
        },
        {
          "value": 35.0,
          "factor": "hypoalbuminaemia",
          "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": "Ho GT, Mowat C, Goddard CJ, Fennell JM, Shah NB, Prescott RJ, Satsangi J",
        "doi": "10.1111/j.1365-2036.2004.01945.x",
        "id": "ho-2004",
        "pmid": "15142197",
        "source": "Aliment Pharmacol Ther. 2004;19(10):1079-1087",
        "title": "Predicting the outcome of severe ulcerative colitis: development of a novel risk score to aid early selection of patients for second-line medical therapy or surgery"
      },
      "formula": "ho_index",
      "formula_expression": "Ho 2004 day-3 IV-steroid severe UC: stool_points(<4 → 0; 4 ≤ mean_stool_frequency < 6 → 1; 6 ≤ x ≤ 9 → 2; x > 9 → 4) + colonic_dilatation (true → 4) + hypoalbuminaemia (albumin_g_l < 30 → 1); max 9; medical-therapy failure 0–1 → 11%, 2–3 → 43%, ≥4 → 85% (ROC operating point ≥4)",
      "max_score": 9,
      "score": 0,
      "albumin_g_l": 35.0,
      "risk": "low",
      "colonic_dilatation": false,
      "hypoalbuminaemia": false,
      "mean_stool_frequency": 3.0,
      "medical_failure_percent": 11,
      "score_ge_4": false
    },
    {
      "components": [
        {
          "value": 3.0,
          "factor": "mean_stool_frequency",
          "points": 0,
          "present": false
        },
        {
          "factor": "colonic_dilatation",
          "points": 0,
          "present": false
        },
        {
          "value": 35.0,
          "factor": "hypoalbuminaemia",
          "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": "Ho GT, Mowat C, Goddard CJ, Fennell JM, Shah NB, Prescott RJ, Satsangi J",
        "doi": "10.1111/j.1365-2036.2004.01945.x",
        "id": "ho-2004",
        "pmid": "15142197",
        "source": "Aliment Pharmacol Ther. 2004;19(10):1079-1087",
        "title": "Predicting the outcome of severe ulcerative colitis: development of a novel risk score to aid early selection of patients for second-line medical therapy or surgery"
      },
      "formula": "ho_index",
      "formula_expression": "Ho 2004 day-3 IV-steroid severe UC: stool_points(<4 → 0; 4 ≤ mean_stool_frequency < 6 → 1; 6 ≤ x ≤ 9 → 2; x > 9 → 4) + colonic_dilatation (true → 4) + hypoalbuminaemia (albumin_g_l < 30 → 1); max 9; medical-therapy failure 0–1 → 11%, 2–3 → 43%, ≥4 → 85% (ROC operating point ≥4)",
      "max_score": 9,
      "score": 0,
      "albumin_g_l": 35.0,
      "risk": "low",
      "colonic_dilatation": false,
      "hypoalbuminaemia": false,
      "mean_stool_frequency": 3.0,
      "medical_failure_percent": 11,
      "score_ge_4": false
    }
  ]
}

Response

Field	Type	Description
`formula`	string	ho_index
`formula_expression`	string	Ho 2004 day-3 IV-steroid severe UC point score
`score`	integer	Ho points 0-9
`max_score`	integer	9
`risk`	string	low (score 0-1), intermediate (2-3), or high (≥4). High is the Ho 2004 ROC operating point.
`medical_failure_percent`	integer	Printed Ho 2004 medical-therapy failure: 11 if score 0-1, 43 if 2-3, 85 if ≥4. Not a colectomy probability.
`score_ge_4`	boolean	true when score ≥ 4 (Ho 2004 ROC operating point). Not a treatment order.
`mean_stool_frequency`	number	Echo of the caller-assigned three-day mean stool frequency (0-40)
`colonic_dilatation`	boolean	Echo of the caller-assigned colonic-dilatation flag
`albumin_g_l`	number	Albumin used in g/L
`hypoalbuminaemia`	boolean	true when albumin_g_l < 30. 30 g/L is not hypoalbuminaemia.
`components`	array	Per-factor points
`citation`	object	Ho 2004 APT citation
`disclaimer`	string	Not-a-device notice

Example JSON

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

{
  "components": [
    {
      "value": 3.0,
      "factor": "mean_stool_frequency",
      "points": 0,
      "present": false
    },
    {
      "factor": "colonic_dilatation",
      "points": 0,
      "present": false
    },
    {
      "value": 35.0,
      "factor": "hypoalbuminaemia",
      "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": "Ho GT, Mowat C, Goddard CJ, Fennell JM, Shah NB, Prescott RJ, Satsangi J",
    "doi": "10.1111/j.1365-2036.2004.01945.x",
    "id": "ho-2004",
    "pmid": "15142197",
    "source": "Aliment Pharmacol Ther. 2004;19(10):1079-1087",
    "title": "Predicting the outcome of severe ulcerative colitis: development of a novel risk score to aid early selection of patients for second-line medical therapy or surgery"
  },
  "formula": "ho_index",
  "formula_expression": "Ho 2004 day-3 IV-steroid severe UC: stool_points(<4 → 0; 4 ≤ mean_stool_frequency < 6 → 1; 6 ≤ x ≤ 9 → 2; x > 9 → 4) + colonic_dilatation (true → 4) + hypoalbuminaemia (albumin_g_l < 30 → 1); max 9; medical-therapy failure 0–1 → 11%, 2–3 → 43%, ≥4 → 85% (ROC operating point ≥4)",
  "max_score": 9,
  "score": 0,
  "albumin_g_l": 35.0,
  "risk": "low",
  "colonic_dilatation": false,
  "hypoalbuminaemia": false,
  "mean_stool_frequency": 3.0,
  "medical_failure_percent": 11,
  "score_ge_4": false
}

Client errors (HTTP 400)

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

HTTP	Code	When
400	`invalid_ho_stools`	mean_stool_frequency must be a number from 0 to 40 (Ho 2004 three-day mean). Returned before settlement; you are not charged.
400	`invalid_albumin`	albumin_g_dl (1-6) or albumin_g_l (10-60) is required 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

Travis criteria — 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.
Truelove and 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.
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. 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.