# PEG (Krebs) PEG Status: LIVE Price: $0.005 USDC `GET /api/calc/peg` HTML: https://magentlab.com/docs/peg Markdown: https://magentlab.com/docs/peg.md Not a medical device. Not a diagnosis, dose, or listing recommendation. ## What it computes Compute the Krebs 2009 PEG as the unweighted mean of three caller-assigned 0-10 integers (pain_average, enjoyment_of_life, general_activity). Potential range 0-10. Krebs 2009 did not publish a diagnostic cutoff. ## When to use When an agent has already assigned Krebs 2009 PEG integers 0-10 for average pain, enjoyment-of-life interference, and general-activity interference in the past week and needs the published mean, not a pain diagnosis, opioid order, Brief Pain Inventory total, or an invented severity band. ## When not to use - Not a medical device and not a pain diagnosis or opioid order. - Each item is a caller-assigned integer 0-10. magent does not interview the patient. - Krebs 2009 did not publish a diagnostic cutoff. magent does not invent mild, moderate, or severe bands. - This is the three-item PEG mean, not the full Brief Pain Inventory. ## Formula ``` PEG = (pain_average + enjoyment_of_life + general_activity) / 3; each caller-assigned 0-10; Krebs 2009; potential range 0-10 ``` ## Citation [Development and initial validation of the PEG, a three-item scale assessing pain intensity and interference](https://doi.org/10.1007/s11606-009-0981-1) Krebs EE, Lorenz KA, Bair MJ, Damush TM, Wu J, Sutherland JM, Asch SM, Kroenke K J Gen Intern Med. 2009;24(6):733-738 DOI: [10.1007/s11606-009-0981-1](https://doi.org/10.1007/s11606-009-0981-1) ## Worked example ### All items 0 Given: `enjoyment_of_life=0, general_activity=0, pain_average=0` 1. PEG = (0 + 0 + 0) / 3 2. Score = 0.0 (max 10) ### Uneven items 1, 2, 4 Given: `enjoyment_of_life=2, general_activity=4, pain_average=1` 1. PEG = (1 + 2 + 4) / 3 = 7/3 = 2.333… 2. Score = 2.3 (max 10) ## Also searched as - PEG - PEG scale - Pain Enjoyment General activity - Krebs PEG - Krebs 2009 PEG - three-item PEG - pain interference scale - PEG score ## Parameters - `pain_average` (integer, required): Caller-assigned Krebs 2009 PEG item (integer 0-10): "What number best describes your pain on average in the past week?" 0 = no pain, 10 = pain as bad as you can imagine. magent does not interview the patient. - `enjoyment_of_life` (integer, required): Caller-assigned Krebs 2009 PEG interference with enjoyment of life in the past week (integer 0-10). 0 = does not interfere, 10 = completely interferes. magent does not interview the patient. - `general_activity` (integer, required): Caller-assigned Krebs 2009 PEG interference with general activity in the past week (integer 0-10). 0 = does not interfere, 10 = completely interferes. magent does not interview the patient. ## 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/peg` 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": [ { "enjoyment_of_life": "0", "general_activity": "0", "pain_average": "0" }, { "enjoyment_of_life": "0", "general_activity": "0", "pain_average": "0" } ] } ``` Human paywall (two-item fixture): https://api.magentlab.com/paywall/bulk/peg Example 200: ```json { "count": 2, "path": "/api/calc/peg", "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": "Krebs EE, Lorenz KA, Bair MJ, Damush TM, Wu J, Sutherland JM, Asch SM, Kroenke K", "doi": "10.1007/s11606-009-0981-1", "id": "krebs-2009", "pmid": "19418100", "source": "J Gen Intern Med. 2009;24(6):733-738", "title": "Development and initial validation of the PEG, a three-item scale assessing pain intensity and interference" }, "formula": "peg", "formula_expression": "PEG = (pain_average + enjoyment_of_life + general_activity) / 3; each caller-assigned 0-10; Krebs 2009; potential range 0-10", "max_score": 10, "score": 0.0, "enjoyment_of_life": 0, "general_activity": 0, "pain_average": 0 }, { "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": "Krebs EE, Lorenz KA, Bair MJ, Damush TM, Wu J, Sutherland JM, Asch SM, Kroenke K", "doi": "10.1007/s11606-009-0981-1", "id": "krebs-2009", "pmid": "19418100", "source": "J Gen Intern Med. 2009;24(6):733-738", "title": "Development and initial validation of the PEG, a three-item scale assessing pain intensity and interference" }, "formula": "peg", "formula_expression": "PEG = (pain_average + enjoyment_of_life + general_activity) / 3; each caller-assigned 0-10; Krebs 2009; potential range 0-10", "max_score": 10, "score": 0.0, "enjoyment_of_life": 0, "general_activity": 0, "pain_average": 0 } ] } ``` ## Response fields - `formula` (string): peg - `formula_expression` (string): Exact expression used - `score` (number): Unweighted mean of the three items, 1 decimal - `max_score` (integer): Always 10 - `pain_average` (integer): Caller-assigned average pain in the past week, 0-10 - `enjoyment_of_life` (integer): Caller-assigned enjoyment-of-life interference in the past week, 0-10 - `general_activity` (integer): Caller-assigned general-activity interference in the past week, 0-10 - `citation` (object): Krebs et al. J Gen Intern Med 2009 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": "Krebs EE, Lorenz KA, Bair MJ, Damush TM, Wu J, Sutherland JM, Asch SM, Kroenke K", "doi": "10.1007/s11606-009-0981-1", "id": "krebs-2009", "pmid": "19418100", "source": "J Gen Intern Med. 2009;24(6):733-738", "title": "Development and initial validation of the PEG, a three-item scale assessing pain intensity and interference" }, "formula": "peg", "formula_expression": "PEG = (pain_average + enjoyment_of_life + general_activity) / 3; each caller-assigned 0-10; Krebs 2009; potential range 0-10", "max_score": 10, "score": 0.0, "enjoyment_of_life": 0, "general_activity": 0, "pain_average": 0 } ``` ## Errors - HTTP 400 `invalid_peg_item`: pain_average, enjoyment_of_life, and general_activity must each be an integer from 0 to 10 (Krebs 2009 PEG). 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 - [PAINAD](https://magentlab.com/docs/painad) — Sum five caller-assigned Warden 2003 PAINAD integers (0-2) and return the published total (max 10). - [FLACC](https://magentlab.com/docs/flacc) — Sum five caller-assigned Merkel 1997 FLACC integers (0-2) and return the published total (max 10). - [CPOT](https://magentlab.com/docs/cpot) — Sum four caller-assigned Gélinas 2006 CPOT integers (0-2) and return the published total (max 8). The fourth item is ventilator_compliance when intubated or vocalization when extubated. - [BPS](https://magentlab.com/docs/bps) — Sum three caller-assigned Payen 2001 BPS integers (1-4) and return the published total (range 3-12). ## 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. HTTP 402 never includes the tool JSON. - 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.