Emergency · LIVE

Ottawa SAH Rule

Apply the Perry 2013 Ottawa SAH Rule and return whether investigation is indicated from age and five caller-assigned high-risk findings.

LIVE $0.005 USDC GET /api/calc/ottawa_sah

Markdown: /docs/ottawa-sah.md · Canonical: https://magentlab.com/docs/ottawa-sah

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

What it computes

Apply the Perry 2013 Ottawa SAH Rule and return whether investigation is indicated from age and five caller-assigned high-risk findings.

When to use

When an agent has caller-assigned findings for acute headache and needs the published six-variable investigation rule, not a diagnosis of SAH.

When not to use

• Not a diagnosis of subarachnoid hemorrhage. magent does not examine the neck.
• Not Hunt-Hess grade and not Fisher grade.
• Inclusion as published is alert, neurologically intact adults with nontraumatic headache peaking within 1 hour. magent does not take GCS or time-to-peak; the caller applies inclusion.
• Limited neck flexion is an examination finding assigned by the caller.
• Thunderclap headache means instantly peaking pain as published.

Formula

Investigation indicated iff age >= 40 or neck_pain_or_stiffness or witnessed_loc or onset_during_exertion or thunderclap_headache or limited_neck_flexion

Citation

Title

Clinical decision rules to rule out subarachnoid hemorrhage for acute headache

Authors

Perry JJ, Stiell IG, Sivilotti MLA, et al.

Source

JAMA. 2013;310(12):1248-1255

DOI

10.1001/jama.2013.278018

Worked example

Also searched as

• Ottawa SAH Rule
• Ottawa subarachnoid hemorrhage rule
• Perry SAH rule
• thunderclap headache rule
• Ottawa SAH
• Perry 2013 JAMA headache
• SAH decision rule
• subarachnoid hemorrhage rule-out

Try

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

/api/calc/ottawa_sah?age=30&neck_pain_or_stiffness=false&witnessed_loc=false&onset_during_exertion=false&thunderclap_headache=false&limited_neck_flexion=false

Full URL: https://api.magentlab.com/api/calc/ottawa_sah?age=30&neck_pain_or_stiffness=false&witnessed_loc=false&onset_during_exertion=false&thunderclap_headache=false&limited_neck_flexion=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/ottawa_sah?age=30&neck_pain_or_stiffness=false&witnessed_loc=false&onset_during_exertion=false&thunderclap_headache=false&limited_neck_flexion=false"

Parameters

Bulk (POST)

POST the same path with a JSON items array. Price is n times the GET unit. Invalid items return HTTP 400 before settlement.

POST /api/calc/ottawa_sah Max 25 unit_amount * n PREVIEW

• 1 to 25 items. Each item uses the same keys as the GET query parameters.
• 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": "30",
      "limited_neck_flexion": "false",
      "neck_pain_or_stiffness": "false",
      "onset_during_exertion": "false",
      "thunderclap_headache": "false",
      "witnessed_loc": "false"
    },
    {
      "age": "30",
      "limited_neck_flexion": "false",
      "neck_pain_or_stiffness": "false",
      "onset_during_exertion": "false",
      "thunderclap_headache": "false",
      "witnessed_loc": "false"
    }
  ]
}

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/ottawa_sah",
  "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": "Perry JJ, Stiell IG, Sivilotti MLA, et al.",
        "doi": "10.1001/jama.2013.278018",
        "id": "perry-2013",
        "source": "JAMA. 2013;310(12):1248-1255",
        "title": "Clinical decision rules to rule out subarachnoid hemorrhage for acute headache"
      },
      "formula": "ottawa_sah",
      "formula_expression": "Investigation indicated iff age >= 40 or neck_pain_or_stiffness or witnessed_loc or onset_during_exertion or thunderclap_headache or limited_neck_flexion",
      "age_years": 30,
      "criteria": [
        {
          "value": 30,
          "factor": "age_ge_40",
          "met": false
        },
        {
          "factor": "neck_pain_or_stiffness",
          "met": false
        },
        {
          "factor": "witnessed_loc",
          "met": false
        },
        {
          "factor": "onset_during_exertion",
          "met": false
        },
        {
          "factor": "thunderclap_headache",
          "met": false
        },
        {
          "factor": "limited_neck_flexion",
          "met": false
        }
      ],
      "investigation_indicated": 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": "Perry JJ, Stiell IG, Sivilotti MLA, et al.",
        "doi": "10.1001/jama.2013.278018",
        "id": "perry-2013",
        "source": "JAMA. 2013;310(12):1248-1255",
        "title": "Clinical decision rules to rule out subarachnoid hemorrhage for acute headache"
      },
      "formula": "ottawa_sah",
      "formula_expression": "Investigation indicated iff age >= 40 or neck_pain_or_stiffness or witnessed_loc or onset_during_exertion or thunderclap_headache or limited_neck_flexion",
      "age_years": 30,
      "criteria": [
        {
          "value": 30,
          "factor": "age_ge_40",
          "met": false
        },
        {
          "factor": "neck_pain_or_stiffness",
          "met": false
        },
        {
          "factor": "witnessed_loc",
          "met": false
        },
        {
          "factor": "onset_during_exertion",
          "met": false
        },
        {
          "factor": "thunderclap_headache",
          "met": false
        },
        {
          "factor": "limited_neck_flexion",
          "met": false
        }
      ],
      "investigation_indicated": false
    }
  ]
}

Response

Example JSON

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

{
  "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": "Perry JJ, Stiell IG, Sivilotti MLA, et al.",
    "doi": "10.1001/jama.2013.278018",
    "id": "perry-2013",
    "source": "JAMA. 2013;310(12):1248-1255",
    "title": "Clinical decision rules to rule out subarachnoid hemorrhage for acute headache"
  },
  "formula": "ottawa_sah",
  "formula_expression": "Investigation indicated iff age >= 40 or neck_pain_or_stiffness or witnessed_loc or onset_during_exertion or thunderclap_headache or limited_neck_flexion",
  "age_years": 30,
  "criteria": [
    {
      "value": 30,
      "factor": "age_ge_40",
      "met": false
    },
    {
      "factor": "neck_pain_or_stiffness",
      "met": false
    },
    {
      "factor": "witnessed_loc",
      "met": false
    },
    {
      "factor": "onset_during_exertion",
      "met": false
    },
    {
      "factor": "thunderclap_headache",
      "met": false
    },
    {
      "factor": "limited_neck_flexion",
      "met": false
    }
  ],
  "investigation_indicated": false
}

Client errors (HTTP 400)

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

Related tools

• Glasgow Coma Scale — Compute the Glasgow Coma Scale as the sum of caller-assigned eye, verbal, and motor integers. The 1974 or 1976 edition is required.
• ICH Score — Compute the Hemphill 2001 ICH Score from caller-assigned GCS, age, infratentorial origin, ICH volume, and IVH.

Payment

Required query parameters must be present and valid. 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

• Invalid query parameters return HTTP 400 before settlement. You are not charged.
• Settlement finishes before the tool executes (paymentFlow upfront). 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.