# Nottingham hip fracture score (Maxwell) NHFS Status: LIVE Price: $0.005 USDC `GET /api/calc/nhfs` HTML: https://magentlab.com/docs/nhfs Markdown: https://magentlab.com/docs/nhfs.md 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 [Development and validation of a preoperative scoring system to predict 30 day mortality in patients undergoing hip fracture surgery](https://doi.org/10.1093/bja/aen236) Maxwell MJ, Moran CG, Moppett IK Br J Anaesth. 2008;101(4):511-517 DOI: [10.1093/bja/aen236](https://doi.org/10.1093/bja/aen236) ## Worked example ### Age 70, female, hemoglobin 12 g/dL, flags false Given: `age=70, amts_le_6=false, comorbidities_ge_2=false, hemoglobin_g_dl=12, lives_in_institution=false, malignancy=false, sex=female` 1. Age 70 is 66-85 → 3; female → 0; hemoglobin 12 g/dL is not ≤10 → 0; all flags false → 0 2. Score = 3 (max 10) ### Maximum integer score Given: `age=86, amts_le_6=true, comorbidities_ge_2=true, hemoglobin_g_dl=10, lives_in_institution=true, malignancy=true, sex=male` 1. Age 86 ≥86 → 4; male → 1; hemoglobin 10 g/dL ≤10 → 1; four flags true → 4 2. 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 ## Parameters - `age` (integer, required): Age in years (18-120). ≤65 scores 0; 66-85 scores 3; ≥86 scores 4 (Maxwell 2008). - `sex` (string, required): 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. Method: `POST /api/calc/nhfs` 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": "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" } ] } ``` Human paywall (two-item fixture): https://api.magentlab.com/paywall/bulk/nhfs Example 200: ```json { "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 fields - `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 Frozen fixture. Not a live lookup. ```json { "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 } ``` ## Errors - HTTP 400 `invalid_age`: age must be an integer from 18 to 120 Returned before settlement; you are not charged. - HTTP 400 `invalid_sex`: sex must be female or male Returned before settlement; you are not charged. - HTTP 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. - HTTP 400 `invalid_flag`: boolean clinical flags must be true or false 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 - [RCRI](https://magentlab.com/docs/rcri) — Sum the six Lee 1999 revised cardiac risk index factors and return class I–IV. - [Gupta MICA](https://magentlab.com/docs/gupta-mica) — Compute the Gupta 2011 Table 2 logistic probability of 30-day myocardial infarction or cardiac arrest after surgery from age, ASA class, functional status, creatinine category, and surgery type. ## 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.