# Ottawa Heart Failure Risk Scale OHFRS Status: LIVE Price: $0.005 USDC `GET /api/calc/ohfrs` HTML: https://magentlab.com/docs/ohfrs Markdown: https://magentlab.com/docs/ohfrs.md Not a medical device. Not a diagnosis, dose, or listing recommendation. ## What it computes Sum the ten Stiell 2013 Ottawa Heart Failure Risk Scale flags and return the integer point total (max 15). ## When to use When an agent needs the published Stiell 2013 OHFRS point total from caller-assigned flags and must not invent ECG, walk-test, or laboratory findings or a discharge decision. ## When not to use - Not a medical device. - Not a disposition or discharge order. Not EHMRG. - Apply after ED intervention as in Stiell 2013. magent does not walk the patient or interpret the ECG. - The caller assigns all ten flags after applying the published cutoffs. magent does not assay labs. ## Formula ``` 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% ``` ## Citation [A risk scoring system to identify emergency department patients with heart failure at high risk for serious adverse events](https://doi.org/10.1111/acem.12056) Stiell IG, Clement CM, Brison RJ, et al. Acad Emerg Med. 2013;20(1):17-26 DOI: [10.1111/acem.12056](https://doi.org/10.1111/acem.12056) ## Worked example ### All ten flags false Given: `co2_ge_35_mmol_l=false, history_stroke_or_tia=false, hr_arrival_ge_110=false, intubation_respiratory_distress=false, new_ischemic_ecg=false, ntprobnp_ge_5000=false, sao2_lt_90_arrival=false, troponin_mi_level=false, urea_ge_12_mmol_l=false, walk_test_hr_ge_110_or_unable=false` 1. Ten findings absent → 0 each 2. Score = 0 (max 15) ### All ten flags true Given: `co2_ge_35_mmol_l=true, history_stroke_or_tia=true, hr_arrival_ge_110=true, intubation_respiratory_distress=true, new_ischemic_ecg=true, ntprobnp_ge_5000=true, sao2_lt_90_arrival=true, troponin_mi_level=true, urea_ge_12_mmol_l=true, walk_test_hr_ge_110_or_unable=true` 1. 1+2+2+1+1+2+1+2+2+1 2. Score = 15 (max 15) ## Also searched as - Ottawa Heart Failure Risk Scale - OHFRS - Stiell heart failure risk - Ottawa HF risk scale - Stiell 2013 OHFRS - emergency heart failure SAE - Ottawa Heart Failure Risk Score - NT-proBNP heart failure ED score ## Parameters - `history_stroke_or_tia` (boolean, required): History of stroke or TIA as assigned by the caller (Stiell 2013; 1 point if true). true or false. magent does not take the history. - `intubation_respiratory_distress` (boolean, required): Intubation for respiratory distress as assigned by the caller (Stiell 2013; 2 points if true). true or false. - `hr_arrival_ge_110` (boolean, required): Heart rate on ED arrival >=110 as assigned by the caller after applying the Stiell 2013 cutoff (2 points if true). true or false. magent does not measure heart rate. - `sao2_lt_90_arrival` (boolean, required): Oxygen saturation <90% on ED arrival as assigned by the caller after applying the Stiell 2013 cutoff (1 point if true). true or false. magent does not measure saturation. - `walk_test_hr_ge_110_or_unable` (boolean, required): Heart rate >=110 during the 3-minute walk test, or unable to perform the walk test, as assigned by the caller after ED intervention (Stiell 2013; 1 point if true). true or false. magent does not walk the patient. - `new_ischemic_ecg` (boolean, required): New ischemic ECG changes as assigned by the caller (Stiell 2013 derivation; 2 points if true). true or false. magent does not interpret the ECG. - `urea_ge_12_mmol_l` (boolean, required): Urea >=12 mmol/L as assigned by the caller after applying the Stiell 2013 cutoff (1 point if true). true or false. magent does not assay urea. - `co2_ge_35_mmol_l` (boolean, required): Serum CO2 >=35 mmol/L as assigned by the caller after applying the Stiell 2013 cutoff (2 points if true). true or false. magent does not assay CO2. - `troponin_mi_level` (boolean, required): Troponin I or T elevated to MI level as assigned by the caller (Stiell 2013; 2 points if true). true or false. magent does not assay troponin. - `ntprobnp_ge_5000` (boolean, required): NT-proBNP >=5000 ng/L as assigned by the caller after applying the Stiell 2013 cutoff (1 point if true). true or false. magent does not assay NT-proBNP. ## Bulk (POST) POST the same path with a JSON items array. The first item is the GET unit; each additional item is $0.002. Invalid items return HTTP 400 before settlement. Method: `POST /api/calc/ohfrs` Max items: 25 Price: unit_amount + extra_item_amount * (n - 1) (unit 5000 atomic, extra 2000 atomic) Status: PREVIEW - 1 to 25 items. Each item uses the same keys as the GET query parameters. - POST of 1 item costs the same as GET. Lists longer than 25: chunk into multiple POSTs. Extra items still execute; do not pad dummy rows. - 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": [ { "co2_ge_35_mmol_l": "false", "history_stroke_or_tia": "false", "hr_arrival_ge_110": "false", "intubation_respiratory_distress": "false", "new_ischemic_ecg": "false", "ntprobnp_ge_5000": "false", "sao2_lt_90_arrival": "false", "troponin_mi_level": "false", "urea_ge_12_mmol_l": "false", "walk_test_hr_ge_110_or_unable": "false" }, { "co2_ge_35_mmol_l": "false", "history_stroke_or_tia": "false", "hr_arrival_ge_110": "false", "intubation_respiratory_distress": "false", "new_ischemic_ecg": "false", "ntprobnp_ge_5000": "false", "sao2_lt_90_arrival": "false", "troponin_mi_level": "false", "urea_ge_12_mmol_l": "false", "walk_test_hr_ge_110_or_unable": "false" } ] } ``` Human paywall (two-item fixture): https://api.magentlab.com/paywall/bulk/ohfrs Example 200: ```json { "count": 2, "path": "/api/calc/ohfrs", "items": [ { "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.", "citation": { "authors": "Stiell IG, Clement CM, Brison RJ, et al.", "doi": "10.1111/acem.12056", "id": "stiell-2013", "pmid": "23570474", "source": "Acad Emerg Med. 2013;20(1):17-26", "title": "A risk scoring system to identify emergency department patients with heart failure at high risk for serious adverse events" }, "formula": "ohfrs", "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%", "max_score": 15, "score": 0 }, { "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.", "citation": { "authors": "Stiell IG, Clement CM, Brison RJ, et al.", "doi": "10.1111/acem.12056", "id": "stiell-2013", "pmid": "23570474", "source": "Acad Emerg Med. 2013;20(1):17-26", "title": "A risk scoring system to identify emergency department patients with heart failure at high risk for serious adverse events" }, "formula": "ohfrs", "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%", "max_score": 15, "score": 0 } ] } ``` ## Response fields - `formula` (string): ohfrs - `formula_expression` (string): Exact expression used - `score` (integer): OHFRS points 0-15 (Stiell 2013) - `max_score` (integer): 15 - `components` (array): Per-flag points - `citation` (object): Stiell et al. Acad Emerg Med 2013 citation - `disclaimer` (string): Not-a-device notice ## Example JSON Frozen fixture. Not a live lookup. ```json { "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.", "citation": { "authors": "Stiell IG, Clement CM, Brison RJ, et al.", "doi": "10.1111/acem.12056", "id": "stiell-2013", "pmid": "23570474", "source": "Acad Emerg Med. 2013;20(1):17-26", "title": "A risk scoring system to identify emergency department patients with heart failure at high risk for serious adverse events" }, "formula": "ohfrs", "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%", "max_score": 15, "score": 0 } ``` ## Errors - 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 - [NEWS](https://magentlab.com/docs/news) — Compute the RCP 2012 National Early Warning Score from respiratory rate, SpO2, supplemental oxygen, temperature, systolic BP, heart rate, and caller-assigned AVPU. - [MEWS](https://magentlab.com/docs/mews) — Compute the Subbe 2001 modified Early Warning Score from systolic BP, heart rate, respiratory rate, temperature, and caller-assigned AVPU. - [Killip](https://magentlab.com/docs/killip) — Return the Killip and Kimball 1967 myocardial-infarction heart-failure class 1-4 from a caller-assigned integer, with the published class description and 1967 CCU hospital mortality. ## Payment Unpaid requests return HTTP 402 even if query parameters or POST items are missing or invalid, so CDP and agents can index the path. After a PAYMENT-SIGNATURE, 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 accepts[0] (exact, EIP-3009) with validBefore = now + maxTimeoutSeconds (600 seconds), or accepts[1] (batch-settlement deposit/voucher) on product GET. Ping and POST {items} stay exact. Magent retries transient facilitator 429/5xx before answering. - Retry the same URL with PAYMENT-SIGNATURE (base64 JSON of accepted and payload). Magent attaches canonical extensions.bazaar on CDP verify/settle; echoing 402 bazaar is optional. - Success is HTTP 200 JSON plus PAYMENT-RESPONSE. exact settles before the tool. batch-settlement verifies (and deposit-settles) before the tool and commits the charge after HTTP 2xx. HTTP 503: retry the same PAYMENT-SIGNATURE. Mint a new exact 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. - offered `batch-settlement` on eip155:8453: Payment-channel vouchers claimed later in batches. Exact stays accepts[0]. Same-path POST {items} is still exact. extra.assetTransferMethod=eip3009 extra.paymentFlow=authorization. - 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. Same-path POST {items} is still scheme exact: one EIP-3009 authorization for GET unit plus $0.002 per extra item. 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 - HTTP 402 is unpaid, including a missing query. After PAYMENT-SIGNATURE, invalid parameters return HTTP 400 before settlement. You are not charged. - exact: settlement finishes before the tool (paymentFlow upfront). batch-settlement: verify/deposit before the tool; chargedCumulativeAmount commits after HTTP 2xx. 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.