# HAT score

HAT

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

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

## What it computes

Compute the Lou 2008 HAT (Hemorrhage After Thrombolysis) score for symptomatic intracranial hemorrhage after stroke thrombolysis from diabetes or baseline glucose >200 mg/dL, pretreatment NIHSS, and easily visible hypodensity on initial CT.

## When to use

When an agent has caller-assigned diabetes, baseline glucose, NIHSS, and CT hypodensity and needs the published HAT total and collective symptomatic ICH percents, without inventing NIHSS, CT findings, an equals-1/3 hypodensity band, or unofficial percents.

## When not to use

- Not a medical device and not a tPA withhold, thrombolysis, or treatment decision.
- Derived in intravenous thrombolysis (Lou 2008). It is not a recommendation for or against alteplase.
- The caller assigns diabetes mellitus, baseline glucose, NIHSS (0-42), and easily visible hypodensity on initial CT. magent does not examine the patient, assign NIHSS, or read CT.
- History of diabetes mellitus OR baseline glucose >200 mg/dL scores 1 (not additive if both). 200.0 mg/dL does not score; 201 does. Glucose is scored in mg/dL; mmol/L converts as mg/dL = mmol/L × 18.
- Pretreatment NIHSS <15 scores 0; 15-20 scores 1; >20 scores 2.
- Hypodensity is none (0), less_than_third (<1/3 MCA, 1), or greater_than_third (>1/3 MCA, 2). There is no published equals-1/3 category.
- Collective symptomatic ICH percents are 2% (0), 5% (1), 10% (2), 15% (3), 44% (>3). Scores 4 and 5 both return 44. magent does not invent other percents.

## Formula

```
HAT = (diabetes OR baseline glucose >200 mg/dL) 1 (not additive) + NIHSS (<15 0, 15-20 1, >20 2) + hypodensity (none 0, <1/3 MCA 1, >1/3 MCA 2); Lou 2008; max 5; collective sICH 2/5/10/15/44% for scores 0/1/2/3/>3
```

## Citation

[The HAT Score: a simple grading scale for predicting hemorrhage after thrombolysis](https://doi.org/10.1212/01.wnl.0000330297.58334.dd)
Lou M, Safdar A, Mehdiratta M, Kumar S, Schlaug G, Caplan L, Searls D, Selim M
Neurology. 2008;71(18):1417-1423
DOI: [10.1212/01.wnl.0000330297.58334.dd](https://doi.org/10.1212/01.wnl.0000330297.58334.dd)

## Worked example

### No diabetes, glucose 6.0 mmol/L, NIHSS 10, no hypodensity

Given: `diabetes=false, glucose_mmol_l=6.0, hypodensity=none, nihss=10`

1. Diabetes false; glucose 6.0 mmol/L → 108.0 mg/dL (not >200) → 0; NIHSS 10 <15 → 0; hypodensity none → 0
2. Score = 0 (max 5); collective sICH 2%


### All items (score 5)

Given: `diabetes=true, glucose_mmol_l=20.0, hypodensity=greater_than_third, nihss=42`

1. Diabetes true (glucose 20.0 mmol/L → 360 mg/dL also >200; not additive) → 1; NIHSS 42 >20 → 2; greater_than_third → 2
2. Score = 5 (max 5); collective sICH 44%


## Also searched as

- HAT score
- Hemorrhage After Thrombolysis
- Lou HAT
- HAT thrombolysis hemorrhage
- symptomatic ICH HAT
- Lou 2008 HAT
- post-tPA hemorrhage HAT
- HAT NIHSS hypodensity

## Parameters

- `diabetes` (boolean, required): History of diabetes mellitus (Lou 2008). true scores 1 on the diabetes-or-glucose item; not additive with glucose >200 mg/dL.
- `glucose_mmol_l` (number, optional): Baseline glucose in mmol/L (2.8-55.5). Provide this or glucose_mg_dl, not both. Converted as mg/dL = mmol/L × 18. Scores 1 on the diabetes-or-glucose item if >200 mg/dL after conversion (200.0 does not).
- `glucose_mg_dl` (number, optional): Baseline glucose in mg/dL (50-1000). Provide this or glucose_mmol_l, not both. >200 scores 1 on the diabetes-or-glucose item if diabetes is false; 200.0 does not (Lou 2008).
- `nihss` (integer, required): Caller-assigned pretreatment NIH Stroke Scale total (integer 0-42). <15 scores 0; 15-20 scores 1; >20 scores 2 (Lou 2008). magent does not compute NIHSS or examine the patient.
- `hypodensity` (string, required): Easily visible hypodensity on initial CT as assigned by the caller (Lou 2008). none scores 0; less_than_third (<1/3 MCA) scores 1; greater_than_third (>1/3 MCA) scores 2. No published equals-1/3 category. magent does not read the CT.

## 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/hat`
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": [
    {
      "diabetes": "false",
      "glucose_mmol_l": "6.0",
      "hypodensity": "none",
      "nihss": "10"
    },
    {
      "diabetes": "false",
      "glucose_mmol_l": "6.0",
      "hypodensity": "none",
      "nihss": "10"
    }
  ]
}
```

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

Example 200:

```json
{
  "count": 2,
  "path": "/api/calc/hat",
  "items": [
    {
      "components": [
        {
          "value": 108.0,
          "factor": "diabetes_or_glucose",
          "points": 0,
          "present": false,
          "diabetes": false
        },
        {
          "value": 10,
          "factor": "nihss",
          "points": 0,
          "present": false
        },
        {
          "value": "none",
          "factor": "hypodensity",
          "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": "Lou M, Safdar A, Mehdiratta M, Kumar S, Schlaug G, Caplan L, Searls D, Selim M",
        "doi": "10.1212/01.wnl.0000330297.58334.dd",
        "id": "lou-2008",
        "pmid": "18955684",
        "source": "Neurology. 2008;71(18):1417-1423",
        "title": "The HAT Score: a simple grading scale for predicting hemorrhage after thrombolysis"
      },
      "formula": "hat",
      "formula_expression": "HAT = (diabetes OR baseline glucose >200 mg/dL) 1 (not additive) + NIHSS (<15 0, 15-20 1, >20 2) + hypodensity (none 0, <1/3 MCA 1, >1/3 MCA 2); Lou 2008; max 5; collective sICH 2/5/10/15/44% for scores 0/1/2/3/>3",
      "max_score": 5,
      "score": 0,
      "nihss": 10,
      "diabetes": false,
      "glucose_mg_dl": 108.0,
      "hypodensity": "none",
      "sich_percent": 2
    },
    {
      "components": [
        {
          "value": 108.0,
          "factor": "diabetes_or_glucose",
          "points": 0,
          "present": false,
          "diabetes": false
        },
        {
          "value": 10,
          "factor": "nihss",
          "points": 0,
          "present": false
        },
        {
          "value": "none",
          "factor": "hypodensity",
          "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": "Lou M, Safdar A, Mehdiratta M, Kumar S, Schlaug G, Caplan L, Searls D, Selim M",
        "doi": "10.1212/01.wnl.0000330297.58334.dd",
        "id": "lou-2008",
        "pmid": "18955684",
        "source": "Neurology. 2008;71(18):1417-1423",
        "title": "The HAT Score: a simple grading scale for predicting hemorrhage after thrombolysis"
      },
      "formula": "hat",
      "formula_expression": "HAT = (diabetes OR baseline glucose >200 mg/dL) 1 (not additive) + NIHSS (<15 0, 15-20 1, >20 2) + hypodensity (none 0, <1/3 MCA 1, >1/3 MCA 2); Lou 2008; max 5; collective sICH 2/5/10/15/44% for scores 0/1/2/3/>3",
      "max_score": 5,
      "score": 0,
      "nihss": 10,
      "diabetes": false,
      "glucose_mg_dl": 108.0,
      "hypodensity": "none",
      "sich_percent": 2
    }
  ]
}
```

## Response fields

- `formula` (string): hat
- `formula_expression` (string): Exact expression used
- `score` (integer): HAT points 0-5
- `max_score` (integer): Always 5
- `sich_percent` (number): Lou 2008 collective symptomatic ICH percent: 2 (0), 5 (1), 10 (2), 15 (3), 44 (>3). Scores 4 and 5 both 44.
- `diabetes` (boolean): Whether history of diabetes mellitus was assigned
- `glucose_mg_dl` (number): Baseline glucose in mg/dL (mmol/L inputs converted ×18)
- `nihss` (integer): Caller-assigned NIHSS used for the <15 / 15-20 / >20 points
- `hypodensity` (string): none, less_than_third, or greater_than_third
- `components` (array): Per-item Lou 2008 points
- `citation` (object): Lou 2008 Neurology citation
- `disclaimer` (string): Not-a-device notice

## Example JSON

Frozen fixture. Not a live lookup.

```json
{
  "components": [
    {
      "value": 108.0,
      "factor": "diabetes_or_glucose",
      "points": 0,
      "present": false,
      "diabetes": false
    },
    {
      "value": 10,
      "factor": "nihss",
      "points": 0,
      "present": false
    },
    {
      "value": "none",
      "factor": "hypodensity",
      "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": "Lou M, Safdar A, Mehdiratta M, Kumar S, Schlaug G, Caplan L, Searls D, Selim M",
    "doi": "10.1212/01.wnl.0000330297.58334.dd",
    "id": "lou-2008",
    "pmid": "18955684",
    "source": "Neurology. 2008;71(18):1417-1423",
    "title": "The HAT Score: a simple grading scale for predicting hemorrhage after thrombolysis"
  },
  "formula": "hat",
  "formula_expression": "HAT = (diabetes OR baseline glucose >200 mg/dL) 1 (not additive) + NIHSS (<15 0, 15-20 1, >20 2) + hypodensity (none 0, <1/3 MCA 1, >1/3 MCA 2); Lou 2008; max 5; collective sICH 2/5/10/15/44% for scores 0/1/2/3/>3",
  "max_score": 5,
  "score": 0,
  "nihss": 10,
  "diabetes": false,
  "glucose_mg_dl": 108.0,
  "hypodensity": "none",
  "sich_percent": 2
}
```

## Errors

- HTTP 400 `invalid_flag`: boolean clinical flags must be true or false Returned before settlement; you are not charged.
- HTTP 400 `invalid_glucose`: glucose_mg_dl (50-1000) or glucose_mmol_l (2.8-55.5) is required Returned before settlement; you are not charged.
- HTTP 400 `invalid_nihss`: nihss must be an integer from 0 to 42. Returned before settlement; you are not charged.
- HTTP 400 `invalid_hat_hypodensity`: hypodensity must be none, less_than_third, or greater_than_third (Lou 2008). 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

- [SEDAN](https://magentlab.com/docs/sedan) — Compute the Strbian 2012 SEDAN score (Sugar, Early infarct signs, (hyper)Dense artery, Age, NIHSS) for symptomatic intracranial hemorrhage after stroke thrombolysis.
- [DRAGON](https://magentlab.com/docs/dragon) — Compute the Strbian 2012 DRAGON score (Dense artery / early infarct signs, prestroke mRS, Age, Glucose, Onset-to-treatment, NIHSS) for 3-month outcome after IV thrombolysis-treated ischemic stroke.

## 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.