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Ottawa SAH Rule Calculator (Perry 2013)
x402
Ottawa SAH Rule Calculator (Perry 2013) is a paid API for AI agents from api.magentlab.com, paid per call via x402, $0.005/call, status unknown (last checked 2026-09-15).
Applies the Ottawa Subarachnoid Hemorrhage rule to determine whether further investigation for SAH is warranted in adult patients presenting with acute headache
Price / call$0.005
Success—
StatusUnknown
How this service works
Ottawa SAH Rule (Perry 2013 JAMA). Investigate when any of six findings is present: age 40 or older, neck pain or stiffness, witnessed loss of consciousness, onset during exertion, thunderclap headache (instantly peaking pain), or limited neck flexion on examination. Not a diagnosis of SAH, not Hunt-Hess, and not Fisher grade. For alert, neurologically intact adults with nontraumatic headache peaking within 1 hour as published. magent does not examine the neck.
Output
Returns whether the Ottawa SAH rule criteria are met and whether further investigation for subarachnoid hemorrhage is indicated, based on the six clinical findings (age ≥40, neck pain/stiffness, witnessed LOC, exertional onset, thunderclap headache, limited neck flexion). Not a diagnosis and does not replace clinical judgment.
Example use cases
Emergency triage for thunderclap headache
“I have a 52-year-old alert patient in the ED with a thunderclap headache that peaked instantly — no neck stiffness, no witnessed LOC, no exertional onset, and neck flexion looks normal. Does the Ottawa SAH rule say I should investigate?”
Screening headache with neck stiffness
“Patient is 38 years old, neurologically intact, came in with a headache that peaked within an hour and is complaining of neck pain. No thunderclap onset, no witnessed loss of consciousness, no exertional trigger, no limited neck flexion. Apply the Ottawa SAH decision rule.”
Elderly patient with exertional headache
“Can you run the Ottawa SAH rule on a 67-year-old who developed a severe headache during exercise? No neck pain or stiffness, no witnessed loss of consciousness, no thunderclap quality, and no limited neck flexion on exam.”
Technical details
Endpoint
GEThttps://api.magentlab.com/api/calc/ottawa_sahWhen to prefer
Use this endpoint when you need to apply the validated Ottawa SAH Rule (Perry 2013, JAMA) to alert, neurologically intact adults with nontraumatic headache peaking within one hour. Prefer this over general clinical reasoning when you need a reproducible, evidence-based binary screening result. Not suitable for Hunt-Hess grading, Fisher grade, traumatic headache, or altered mental status patients.
Side effects
- Missing any required query parameter (age, neck_pain_or_stiffness, witnessed_loc, onset_during_exertion, thunderclap_headache, limited_neck_flexion) returns a validation error
- Age outside valid range (below 18 or above 120) may return an error
- Incorrect type for boolean fields (e.g. string instead of boolean) causes schema validation failure
- Payment not included or insufficient USDC balance returns 402 payment required
Input
Schema · Request body
| Field | Type | Description |
|---|---|---|
| inputrequired | object | |
| output | object |
Output
Schema · Response
{
"type": "json",
"example": {
"path": "/api/calc/ottawa_sah",
"count": 2,
"items": [
{
"formula": "ottawa_sah",
"citation": {
"id": "perry-2013",
"doi": "10.1001/jama.2013.278018",
"title": "Clinical decision rules to rule out subarachnoid hemorrhage for acute headache",
"source": "JAMA. 2013;310(12):1248-1255",
"authors": "Perry JJ, Stiell IG, Sivilotti MLA, et al."
},
"criteria": [
{
"met": false,
"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"
}
],
"age_years": 30,
"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.",
"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",
"investigation_indicated": false
},
{
"formula": "ottawa_sah",
"citation": {
"id": "perry-2013",
"doi": "10.1001/jama.2013.278018",
"title": "Clinical decision rules to rule out subarachnoid hemorrhage for acute headache",
"source": "JAMA. 2013;310(12):1248-1255",
"authors": "Perry JJ, Stiell IG, Sivilotti MLA, et al."
},
"criteria": [
{
"met": false,
"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"
}
],
"age_years": 30,
"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.",
"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",
"investigation_indicated": false
}
]
}
}Tags
x402
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