Nottingham hip fracture score (Maxwell)

NHFS

Sum the Maxwell 2008 Nottingham hip fracture score from seven preoperative variables and return the integer total (max 10).

LIVE $0.005 USDC GET /api/calc/nhfs

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

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

What it computes

Sum the Maxwell 2008 Nottingham hip fracture score from seven preoperative variables and return the integer total (max 10).

When to use

When an agent needs the published Maxwell 2008 integer NHFS and must not invent a 30-day mortality percent or an operative-clearance decision.

When not to use

Not a medical device and not operative clearance. magent does not clear a patient for surgery.
Integer score only from Maxwell 2008. Does not output predicted 30-day mortality percent. Not the 2012 or 2015 recalibrated mortality models.
magent does not administer the Abbreviated Mental Test. amts_le_6 is a caller-assigned flag (AMTS ≤6/10).
comorbidities_ge_2 and malignancy (Maxwell 2008: active malignancy within 20 years) are caller-assigned; magent does not enumerate comorbidities or take a cancer history.
Hemoglobin ≤10 g/dL scores 1 (10.0 scores; 10.1 does not). Provide hemoglobin_g_dl or hemoglobin_g_l, not both.

Formula

NHFS = age (≤65 0, 66-85 3, ≥86 4) + male 1 + (hemoglobin ≤10 g/dL) 1 + amts_le_6 1 + lives_in_institution 1 + comorbidities_ge_2 1 + malignancy 1; Maxwell 2008 integer score; max 10

Citation

Title: Development and validation of a preoperative scoring system to predict 30 day mortality in patients undergoing hip fracture surgery
Authors: Maxwell MJ, Moran CG, Moppett IK
Source: Br J Anaesth. 2008;101(4):511-517
DOI: 10.1093/bja/aen236

Worked example

Age 70, female, hemoglobin 12 g/dL, flags false

Given: age=70amts_le_6=falsecomorbidities_ge_2=falsehemoglobin_g_dl=12lives_in_institution=falsemalignancy=falsesex=female

Age 70 is 66-85 → 3; female → 0; hemoglobin 12 g/dL is not ≤10 → 0; all flags false → 0
Score = 3 (max 10)

Maximum integer score

Given: age=86amts_le_6=truecomorbidities_ge_2=truehemoglobin_g_dl=10lives_in_institution=truemalignancy=truesex=male

Age 86 ≥86 → 4; male → 1; hemoglobin 10 g/dL ≤10 → 1; four flags true → 4
Score = 10 (max 10)

Also searched as

Nottingham hip fracture score
NHFS
Maxwell hip fracture score
preoperative hip fracture score
Nottingham hip score
hip fracture 30-day mortality score

Try

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

/api/calc/nhfs?age=70&sex=female&hemoglobin_g_dl=12&amts_le_6=false&lives_in_institution=false&comorbidities_ge_2=false&malignancy=false

Full URL: https://api.magentlab.com/api/calc/nhfs?age=70&sex=female&hemoglobin_g_dl=12&amts_le_6=false&lives_in_institution=false&comorbidities_ge_2=false&malignancy=false

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/nhfs?age=70&sex=female&hemoglobin_g_dl=12&amts_le_6=false&lives_in_institution=false&comorbidities_ge_2=false&malignancy=false"

Parameters

Name	Type	Required	Description
`age`	integer	required	Age in years (18-120). ≤65 scores 0; 66-85 scores 3; ≥86 scores 4 (Maxwell 2008).
`sex`	string	required · female, male	female or male. Male scores 1; female scores 0.
`hemoglobin_g_dl`	number	optional	Hemoglobin in g/dL (3-22). Provide this or hemoglobin_g_l, not both. ≤10 g/dL scores 1 (10.0 scores; 10.1 does not).
`hemoglobin_g_l`	number	optional	Hemoglobin in g/L (30-220). Converted as hemoglobin_g_dl = hemoglobin_g_l / 10. Provide this or hemoglobin_g_dl, not both.
`amts_le_6`	boolean	required	Abbreviated Mental Test Score ≤6/10 as assigned by the caller (Maxwell 2008). true or false. magent does not administer AMTS. 1 point if true.
`lives_in_institution`	boolean	required	Lives in an institution as assigned by the caller (Maxwell 2008). true or false. 1 point if true.
`comorbidities_ge_2`	boolean	required	Two or more comorbidities as defined in Maxwell 2008, as assigned by the caller. true or false. magent does not enumerate comorbidities. 1 point if true.
`malignancy`	boolean	required	Active malignancy (Maxwell 2008: within 20 years) as assigned by the caller. true or false. magent does not take a cancer history. 1 point if true.

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/nhfs 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": [
    {
      "age": "70",
      "amts_le_6": "false",
      "comorbidities_ge_2": "false",
      "hemoglobin_g_dl": "12",
      "lives_in_institution": "false",
      "malignancy": "false",
      "sex": "female"
    },
    {
      "age": "70",
      "amts_le_6": "false",
      "comorbidities_ge_2": "false",
      "hemoglobin_g_dl": "12",
      "lives_in_institution": "false",
      "malignancy": "false",
      "sex": "female"
    }
  ]
}

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/nhfs",
  "items": [
    {
      "components": [
        {
          "value": 70,
          "factor": "age",
          "points": 3,
          "present": true
        },
        {
          "value": "female",
          "factor": "sex",
          "points": 0,
          "present": false
        },
        {
          "value": 12.0,
          "factor": "hemoglobin",
          "points": 0,
          "present": false
        },
        {
          "factor": "amts_le_6",
          "points": 0,
          "present": false
        },
        {
          "factor": "lives_in_institution",
          "points": 0,
          "present": false
        },
        {
          "factor": "comorbidities_ge_2",
          "points": 0,
          "present": false
        },
        {
          "factor": "malignancy",
          "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": "Maxwell MJ, Moran CG, Moppett IK",
        "doi": "10.1093/bja/aen236",
        "id": "maxwell-2008",
        "pmid": "18723517",
        "source": "Br J Anaesth. 2008;101(4):511-517",
        "title": "Development and validation of a preoperative scoring system to predict 30 day mortality in patients undergoing hip fracture surgery"
      },
      "formula": "nhfs",
      "formula_expression": "NHFS = age (≤65 0, 66-85 3, ≥86 4) + male 1 + (hemoglobin ≤10 g/dL) 1 + amts_le_6 1 + lives_in_institution 1 + comorbidities_ge_2 1 + malignancy 1; Maxwell 2008 integer score; max 10",
      "age_years": 70,
      "max_score": 10,
      "score": 3,
      "sex": "female",
      "hemoglobin_g_dl": 12.0,
      "amts_le_6": false,
      "comorbidities_ge_2": false,
      "lives_in_institution": false,
      "malignancy": false
    },
    {
      "components": [
        {
          "value": 70,
          "factor": "age",
          "points": 3,
          "present": true
        },
        {
          "value": "female",
          "factor": "sex",
          "points": 0,
          "present": false
        },
        {
          "value": 12.0,
          "factor": "hemoglobin",
          "points": 0,
          "present": false
        },
        {
          "factor": "amts_le_6",
          "points": 0,
          "present": false
        },
        {
          "factor": "lives_in_institution",
          "points": 0,
          "present": false
        },
        {
          "factor": "comorbidities_ge_2",
          "points": 0,
          "present": false
        },
        {
          "factor": "malignancy",
          "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": "Maxwell MJ, Moran CG, Moppett IK",
        "doi": "10.1093/bja/aen236",
        "id": "maxwell-2008",
        "pmid": "18723517",
        "source": "Br J Anaesth. 2008;101(4):511-517",
        "title": "Development and validation of a preoperative scoring system to predict 30 day mortality in patients undergoing hip fracture surgery"
      },
      "formula": "nhfs",
      "formula_expression": "NHFS = age (≤65 0, 66-85 3, ≥86 4) + male 1 + (hemoglobin ≤10 g/dL) 1 + amts_le_6 1 + lives_in_institution 1 + comorbidities_ge_2 1 + malignancy 1; Maxwell 2008 integer score; max 10",
      "age_years": 70,
      "max_score": 10,
      "score": 3,
      "sex": "female",
      "hemoglobin_g_dl": 12.0,
      "amts_le_6": false,
      "comorbidities_ge_2": false,
      "lives_in_institution": false,
      "malignancy": false
    }
  ]
}

Response

Field	Type	Description
`formula`	string	nhfs
`formula_expression`	string	Exact expression used
`score`	integer	Maxwell 2008 integer points 0-10
`max_score`	integer	Always 10
`age_years`	integer	Age used (years)
`sex`	string	Sex used: female or male
`hemoglobin_g_dl`	number	Hemoglobin used in g/dL (g/L inputs converted as g/dL = g/L / 10)
`amts_le_6`	boolean	Caller-assigned AMTS ≤6/10 flag used
`lives_in_institution`	boolean	Caller-assigned lives-in-institution flag used
`comorbidities_ge_2`	boolean	Caller-assigned ≥2 comorbidities flag used
`malignancy`	boolean	Caller-assigned malignancy flag used
`components`	array	Per-item points
`citation`	object	Maxwell 2008 Br J Anaesth citation
`disclaimer`	string	Not-a-device notice

Example JSON

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

{
  "components": [
    {
      "value": 70,
      "factor": "age",
      "points": 3,
      "present": true
    },
    {
      "value": "female",
      "factor": "sex",
      "points": 0,
      "present": false
    },
    {
      "value": 12.0,
      "factor": "hemoglobin",
      "points": 0,
      "present": false
    },
    {
      "factor": "amts_le_6",
      "points": 0,
      "present": false
    },
    {
      "factor": "lives_in_institution",
      "points": 0,
      "present": false
    },
    {
      "factor": "comorbidities_ge_2",
      "points": 0,
      "present": false
    },
    {
      "factor": "malignancy",
      "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": "Maxwell MJ, Moran CG, Moppett IK",
    "doi": "10.1093/bja/aen236",
    "id": "maxwell-2008",
    "pmid": "18723517",
    "source": "Br J Anaesth. 2008;101(4):511-517",
    "title": "Development and validation of a preoperative scoring system to predict 30 day mortality in patients undergoing hip fracture surgery"
  },
  "formula": "nhfs",
  "formula_expression": "NHFS = age (≤65 0, 66-85 3, ≥86 4) + male 1 + (hemoglobin ≤10 g/dL) 1 + amts_le_6 1 + lives_in_institution 1 + comorbidities_ge_2 1 + malignancy 1; Maxwell 2008 integer score; max 10",
  "age_years": 70,
  "max_score": 10,
  "score": 3,
  "sex": "female",
  "hemoglobin_g_dl": 12.0,
  "amts_le_6": false,
  "comorbidities_ge_2": false,
  "lives_in_institution": false,
  "malignancy": false
}

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_hemoglobin`	hemoglobin_g_l (30-220) or hemoglobin_g_dl (3-22) is required, not both. 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

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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.