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San Francisco Syncope Rule (CHESS Score) Calculator
x402
San Francisco Syncope Rule (CHESS Score) Calculator 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).
Calculates the San Francisco Syncope Rule (CHESS) score from five clinical criteria to identify high-risk syncope patients, returning a criterion count (0–5) and rule-positive flag.
Price / call$0.005
Success—
StatusUnknown
How this service works
San Francisco Syncope Rule (CHESS) from history of CHF, hematocrit, abnormal ECG, shortness of breath, and systolic BP. Returns a 0-5 criterion count and rule-positive if any CHESS item is present. Deterministic published score with citation; not a disposition protocol.
Output
Returns the total number of CHESS criteria met (integer 0–5) and a boolean rule-positive flag indicating whether any single criterion is present, which per the published rule identifies high-risk syncope. Individual criterion contributions are also available to explain which items scored positive.
Example use cases
ED syncope triage risk flagging
“I have a syncope patient in the ED — history of CHF is yes, hematocrit 24%, ECG shows bundle branch block so mark that abnormal, no shortness of breath, and systolic BP is 88. Run the SF Syncope Rule and tell me if they're rule-positive.”
Automatic chart-based CHESS scoring
“Pull the CHESS score for this patient: no CHF history, hematocrit 35%, ECG is normal, they did complain of shortness of breath, and their systolic BP on arrival was 95 mm Hg.”
Clinical documentation QA for syncope visits
“Check whether our attending should have flagged this syncope case as high-risk: CHF history negative, hematocrit 31%, ECG normal, no dyspnea, systolic BP 120. What does the SF Syncope Rule say?”
Technical details
Endpoint
GEThttps://api.magentlab.com/api/calc/sf_syncopeWhen to prefer
Use this endpoint when you need a deterministic, citation-backed implementation of the San Francisco Syncope Rule (CHESS) for syncope risk stratification — particularly when building clinical decision support workflows, automating chart review, or auditing ED syncope management. Prefer this over general-purpose LLM reasoning for medical scoring because it guarantees adherence to the published Elesber/Quinn algorithm with traceable citation, not probabilistic generation. It is not a disposition protocol and should be used alongside clinical judgment.
Side effects
- Missing required query parameters (chf, hematocrit_percent, abnormal_ecg, shortness_of_breath, systolic_bp_mm_hg) returns a validation error
- Hematocrit value outside accepted range (10–70%) returns an out-of-range error
- Systolic BP value outside accepted range (50–250 mm Hg) returns an out-of-range error
- Non-boolean values passed for boolean parameters return a type error
- Payment not included or insufficient USDC triggers a 402 Payment Required response
Input
Schema · Request body
| Field | Type | Description |
|---|---|---|
| inputrequired | object | |
| output | object |
Output
Schema · Response
{
"type": "json",
"example": {
"path": "/api/calc/sf_syncope",
"count": 2,
"items": [
{
"score": 0,
"formula": "sf_syncope",
"citation": {
"id": "quinn-2004",
"doi": "10.1016/S0196-0644(03)00823-0",
"title": "Derivation of the San Francisco Syncope Rule to predict patients with short-term serious outcomes",
"source": "Ann Emerg Med. 2004;43(2):224-232",
"authors": "Quinn JV, Stiell IG, McDermott DA, Sellers KL, Kohn MA, Wells GA"
},
"max_score": 5,
"components": [
{
"factor": "chf",
"points": 0,
"present": false
},
{
"value": 40,
"factor": "hematocrit_lt_30",
"points": 0,
"present": false
},
{
"factor": "abnormal_ecg",
"points": 0,
"present": false
},
{
"factor": "shortness_of_breath",
"points": 0,
"present": false
},
{
"value": 120,
"factor": "systolic_bp_lt_90",
"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.",
"rule_positive": false,
"systolic_bp_mm_hg": 120,
"formula_expression": "CHESS = chf + hematocrit_lt_30 + abnormal_ecg + shortness_of_breath + systolic_bp_lt_90; rule-positive if score ≥ 1; max 5",
"hematocrit_percent": 40
},
{
"score": 0,
"formula": "sf_syncope",
"citation": {
"id": "quinn-2004",
"doi": "10.1016/S0196-0644(03)00823-0",
"title": "Derivation of the San Francisco Syncope Rule to predict patients with short-term serious outcomes",
"source": "Ann Emerg Med. 2004;43(2):224-232",
"authors": "Quinn JV, Stiell IG, McDermott DA, Sellers KL, Kohn MA, Wells GA"
},
"max_score": 5,
"components": [
{
"factor": "chf",
"points": 0,
"present": false
},
{
"value": 40,
"factor": "hematocrit_lt_30",
"points": 0,
"present": false
},
{
"factor": "abnormal_ecg",
"points": 0,
"present": false
},
{
"factor": "shortness_of_breath",
"points": 0,
"present": false
},
{
"value": 120,
"factor": "systolic_bp_lt_90",
"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.",
"rule_positive": false,
"systolic_bp_mm_hg": 120,
"formula_expression": "CHESS = chf + hematocrit_lt_30 + abnormal_ecg + shortness_of_breath + systolic_bp_lt_90; rule-positive if score ≥ 1; max 5",
"hematocrit_percent": 40
}
]
}
}Tags
x402
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