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Ottawa Heart Failure Risk Scale (OHFRS) Calculator
x402
Ottawa Heart Failure Risk Scale (OHFRS) 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).
Computes the Ottawa Heart Failure Risk Scale (OHFRS; Stiell 2013) integer score and associated serious adverse event risk from ten caller-assigned clinical flags for ED heart failure patients.
Price / call$0.005
Success—
StatusUnknown
How this service works
Ottawa Heart Failure Risk Scale (OHFRS; Stiell 2013 derivation). Ten caller-assigned flags (stroke/TIA 1, intubation 2, arrival HR >=110 2, arrival SaO2 <90% 1, walk-test HR >=110 or unable 1, new ischemic ECG 2, urea >=12 mmol/L 1, CO2 >=35 mmol/L 2, troponin at MI level 2, NT-proBNP >=5000 ng/L 1); integer points, max 15. Derivation SAE risk 2.8% to 89.0%. Not a medical device, not a disposition or discharge order, not EHMRG. magent does not walk the patient or read the ECG.
Output
Returns an integer OHFRS total score (0–15) and the corresponding Stiell 2013 derivation serious adverse event (SAE) risk percentage (ranging from approximately 2.8% to 89.0%), based on the ten Boolean clinical flags provided by the caller.
Example use cases
ED triage risk score for heart failure
“I have a heart failure patient in the ED: no stroke/TIA history, no prior intubation, arrival HR was 118 so that's a yes, SaO2 was 88% on arrival so yes, walk test HR went to 115 so yes, new ischemic ECG changes present, urea is 14 mmol/L so yes, CO2 is 32 so no, troponin is not at MI level, and NT-proBNP is 6200 ng/L so yes — what's their OHFRS score and estimated serious adverse event risk?”
Low-risk heart failure discharge consideration
“My heart failure patient has all ten OHFRS flags negative — no stroke history, no prior intubation, HR under 110 on arrival, SaO2 fine, completed walk test under 110, no ischemic ECG changes, urea under 12, CO2 under 35, troponin normal, NT-proBNP under 5000. Can you compute their Ottawa Heart Failure Risk Scale score so I can see where they fall on the Stiell 2013 SAE risk range?”
High-risk multilabel heart failure scoring
“Run the OHFRS on this patient: stroke history yes, prior intubation yes, arrival HR >=110 yes, SaO2 <90% yes, walk-test unable yes, new ischemic ECG yes, urea >=12 yes, CO2 <35 so no, troponin at MI level yes, NT-proBNP >=5000 yes — give me the total score and the corresponding serious adverse event risk percentage.”
Technical details
Endpoint
GEThttps://api.magentlab.com/api/calc/ohfrsWhen to prefer
Use this endpoint when you need to compute the validated Stiell 2013 OHFRS integer score and SAE risk for an acute heart failure patient presenting to the emergency department. Prefer it over manual calculation to eliminate arithmetic errors. It is distinct from EHMRG and other heart failure tools. Requires that the calling system has already measured or interpreted each clinical parameter (vitals, labs, ECG, walk test) and can supply them as Boolean flags.
Side effects
- Missing any of the ten required Boolean query parameters returns a 400 or validation error
- Non-boolean values for flag parameters cause schema validation failure
- Network or service unavailability returns a 5xx error
- Payment not included or insufficient USDC balance triggers x402 payment-required response
Input
Schema · Request body
| Field | Type | Description |
|---|---|---|
| inputrequired | object | |
| output | object |
Output
Schema · Response
{
"type": "json",
"example": {
"path": "/api/calc/ohfrs",
"count": 2,
"items": [
{
"score": 0,
"formula": "ohfrs",
"citation": {
"id": "stiell-2013",
"doi": "10.1111/acem.12056",
"pmid": "23570474",
"title": "A risk scoring system to identify emergency department patients with heart failure at high risk for serious adverse events",
"source": "Acad Emerg Med. 2013;20(1):17-26",
"authors": "Stiell IG, Clement CM, Brison RJ, et al."
},
"max_score": 15,
"components": [
{
"factor": "history_stroke_or_tia",
"points": 0,
"present": false
},
{
"factor": "intubation_respiratory_distress",
"points": 0,
"present": false
},
{
"factor": "hr_arrival_ge_110",
"points": 0,
"present": false
},
{
"factor": "sao2_lt_90_arrival",
"points": 0,
"present": false
},
{
"factor": "walk_test_hr_ge_110_or_unable",
"points": 0,
"present": false
},
{
"factor": "new_ischemic_ecg",
"points": 0,
"present": false
},
{
"factor": "urea_ge_12_mmol_l",
"points": 0,
"present": false
},
{
"factor": "co2_ge_35_mmol_l",
"points": 0,
"present": false
},
{
"factor": "troponin_mi_level",
"points": 0,
"present": false
},
{
"factor": "ntprobnp_ge_5000",
"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.",
"formula_expression": "OHFRS = history_stroke_or_tia(1) + intubation_respiratory_distress(2) + hr_arrival_ge_110(2) + sao2_lt_90_arrival(1) + walk_test_hr_ge_110_or_unable(1) + new_ischemic_ecg(2) + urea_ge_12_mmol_l(1) + co2_ge_35_mmol_l(2) + troponin_mi_level(2) + ntprobnp_ge_5000(1); Stiell 2013 derivation; max 15; SAE risk varied from 2.8% to 89.0%; admission thresholds of total score 1, 2, or 3 had sensitivities 95.2 / 80.6 / 64.5%"
},
{
"score": 0,
"formula": "ohfrs",
"citation": {
"id": "stiell-2013",
"doi": "10.1111/acem.12056",
"pmid": "23570474",
"title": "A risk scoring system to identify emergency department patients with heart failure at high risk for serious adverse events",
"source": "Acad Emerg Med. 2013;20(1):17-26",
"authors": "Stiell IG, Clement CM, Brison RJ, et al."
},
"max_score": 15,
"components": [
{
"factor": "history_stroke_or_tia",
"points": 0,
"present": false
},
{
"factor": "intubation_respiratory_distress",
"points": 0,
"present": false
},
{
"factor": "hr_arrival_ge_110",
"points": 0,
"present": false
},
{
"factor": "sao2_lt_90_arrival",
"points": 0,
"present": false
},
{
"factor": "walk_test_hr_ge_110_or_unable",
"points": 0,
"present": false
},
{
"factor": "new_ischemic_ecg",
"points": 0,
"present": false
},
{
"factor": "urea_ge_12_mmol_l",
"points": 0,
"present": false
},
{
"factor": "co2_ge_35_mmol_l",
"points": 0,
"present": false
},
{
"factor": "troponin_mi_level",
"points": 0,
"present": false
},
{
"factor": "ntprobnp_ge_5000",
"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.",
"formula_expression": "OHFRS = history_stroke_or_tia(1) + intubation_respiratory_distress(2) + hr_arrival_ge_110(2) + sao2_lt_90_arrival(1) + walk_test_hr_ge_110_or_unable(1) + new_ischemic_ecg(2) + urea_ge_12_mmol_l(1) + co2_ge_35_mmol_l(2) + troponin_mi_level(2) + ntprobnp_ge_5000(1); Stiell 2013 derivation; max 15; SAE risk varied from 2.8% to 89.0%; admission thresholds of total score 1, 2, or 3 had sensitivities 95.2 / 80.6 / 64.5%"
}
]
}
}Tags
x402
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