# Ottawa SAH Rule Ottawa SAH Rule Status: LIVE Price: $0.005 USDC `GET /api/calc/ottawa_sah` HTML: https://magentlab.com/docs/ottawa-sah Markdown: https://magentlab.com/docs/ottawa-sah.md 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 [Clinical decision rules to rule out subarachnoid hemorrhage for acute headache](https://doi.org/10.1001/jama.2013.278018) Perry JJ, Stiell IG, Sivilotti MLA, et al. JAMA. 2013;310(12):1248-1255 DOI: [10.1001/jama.2013.278018](https://doi.org/10.1001/jama.2013.278018) ## Worked example ### All findings absent Given: `age=30, limited_neck_flexion=false, neck_pain_or_stiffness=false, onset_during_exertion=false, thunderclap_headache=false, witnessed_loc=false` 1. Age 30 (under 40) and all five clinical flags false 2. Investigation is not indicated ### Age 40 with no other findings Given: `age=40, limited_neck_flexion=false, neck_pain_or_stiffness=false, onset_during_exertion=false, thunderclap_headache=false, witnessed_loc=false` 1. Age 40 meets the age criterion (39 does not) 2. Investigation is indicated ### Thunderclap headache alone Given: `age=30, limited_neck_flexion=false, neck_pain_or_stiffness=false, onset_during_exertion=false, thunderclap_headache=true, witnessed_loc=false` 1. Age 30 does not meet the age criterion 2. Thunderclap headache (instantly peaking pain) is present 3. Investigation is indicated ## 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 ## Parameters - `age` (integer, required): Age in years (18-120). Age ≥40 meets this criterion; 39 does not. - `neck_pain_or_stiffness` (boolean, required): Neck pain or stiffness as assigned by the caller. true or false. - `witnessed_loc` (boolean, required): Witnessed loss of consciousness. true or false as assigned by the caller. - `onset_during_exertion` (boolean, required): Onset during exertion. true or false as assigned by the caller. - `thunderclap_headache` (boolean, required): Thunderclap headache (instantly peaking pain as published). true or false as assigned by the caller. - `limited_neck_flexion` (boolean, required): Limited neck flexion on examination as assigned by the caller. true or false. magent does not examine the neck. ## 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. Method: `POST /api/calc/ottawa_sah` Max items: 25 Price: unit_amount * n (unit 5000 atomic) Status: 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: ```json { "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" } ] } ``` Human paywall (two-item fixture): https://api.magentlab.com/paywall/bulk/ottawa-sah Example 200: ```json { "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 fields - `formula` (string): ottawa_sah - `formula_expression` (string): Perry 2013 six-variable investigation rule - `investigation_indicated` (boolean): true when any published high-risk finding is present. Not a diagnosis of SAH. - `age_years` (integer): Age used for the ≥40 criterion - `criteria` (array): Per-factor rows with factor and met; age_ge_40 includes the age value - `citation` (object): Perry 2013 JAMA citation - `disclaimer` (string): Not-a-device notice ## Example JSON Frozen fixture. Not a live lookup. ```json { "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 } ``` ## Errors - HTTP 400 `invalid_age`: age must be an integer from 18 to 120 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 - [Glasgow Coma Scale](https://magentlab.com/docs/gcs) — 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](https://magentlab.com/docs/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. - 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 EIP-3009 (scheme exact, assetTransferMethod eip3009) with validBefore = now + accepts[0].maxTimeoutSeconds (600 seconds). That window starts when you sign and must cover wallet confirmation plus CDP verify and settle. Magent retries transient facilitator 429/5xx before answering. Do not send upto or batch-settlement payloads; magent does not offer those schemes. - Retry the same URL with PAYMENT-SIGNATURE (base64 JSON echoing accepted, payload, and extensions when present). - Success is HTTP 200 JSON plus PAYMENT-RESPONSE. Settlement happens before the tool runs. HTTP 503 settlement_uncertain or settle_failed: retry the same PAYMENT-SIGNATURE. Mint a new 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. - 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. - not offered `batch-settlement`: Not offered. Payment-channel vouchers claimed later in batches. Not the same as POST {items} bulk (that is still exact). Same-path POST {items} is still scheme exact: one EIP-3009 authorization for n times the GET unit. 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 - 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.