# Pediatric Crohn's Disease Activity Index (PCDAI) PCDAI Status: LIVE Price: $0.005 USDC `GET /api/calc/pcdai` HTML: https://magentlab.com/docs/pcdai Markdown: https://magentlab.com/docs/pcdai.md Not a medical device. Not a diagnosis, dose, or listing recommendation. ## What it computes Sum eleven caller-assigned Hyams 1991 PCDAI item points and return the published total (max 100). Does not return activity bands. ## When to use When an agent has already assigned Hyams 1991 published point values for the eleven PCDAI items and needs the total, not a diagnosis, CDAI, SES-CD, PUCAI, hematocrit table, or later activity cutoffs. ## When not to use - Not a medical device and not a diagnosis of Crohn's disease or a treatment order. - Each of the eleven items is a caller-assigned published point value from Hyams 1991. magent does not examine the child or assign hematocrit age/sex tables. - Pediatric Crohn's Disease Activity Index (PCDAI). Not the Best 1976 CDAI, not SES-CD, and not PUCAI. - Hyams 1991 did not publish inactive, mild, or moderate cut scores. magent returns score and max_score only and does not apply later Hyams 2005 or other unofficial bands. ## Formula ``` PCDAI = abdominal_pain + stools + well_being + hematocrit + esr + albumin + weight + height + abdomen + perirectal + extra_intestinal; Hyams 1991 caller-assigned item points; hematocrit and esr 0, 2.5, or 5; remaining items 0, 5, or 10; max 100; no published activity bands ``` ## Citation [Development and validation of a pediatric Crohn's disease activity index](https://doi.org/10.1097/00005176-199105000-00001) Hyams JS, Ferry GD, Mandel FS, et al. J Pediatr Gastroenterol Nutr. 1991;12(4):439-447 DOI: [10.1097/00005176-199105000-00001](https://doi.org/10.1097/00005176-199105000-00001) ## Worked example ### All eleven items 0 Given: `abdomen=0, abdominal_pain=0, albumin=0, esr=0, extra_intestinal=0, height=0, hematocrit=0, perirectal=0, stools=0, weight=0, well_being=0` 1. abdominal_pain 0 + stools 0 + well_being 0 + hematocrit 0 + esr 0 + albumin 0 + weight 0 + height 0 + abdomen 0 + perirectal 0 + extra_intestinal 0 2. Score = 0 (max 100). No activity band. ### Published theoretical maximum Given: `abdomen=10, abdominal_pain=10, albumin=10, esr=5, extra_intestinal=10, height=10, hematocrit=5, perirectal=10, stools=10, weight=10, well_being=10` 1. abdominal_pain 10 + stools 10 + well_being 10 + hematocrit 5 + esr 5 + albumin 10 + weight 10 + height 10 + abdomen 10 + perirectal 10 + extra_intestinal 10 2. Score = 100 (max 100). No activity band. ## Also searched as - PCDAI - pediatric Crohn's disease activity index - Hyams PCDAI - pediatric Crohn activity - PCDAI score - Crohn's disease children - Hyams 1991 PCDAI - pediatric Crohn index ## Parameters - `abdominal_pain` (integer, required): Caller-assigned Hyams 1991 PCDAI abdominal pain points (integer 0, 5, or 10): 0 none; 5 mild (brief, does not interfere with activities); 10 moderate/severe (daily, longer lasting, affects activities, nocturnal). magent does not examine the child. - `stools` (integer, required): Caller-assigned Hyams 1991 PCDAI stools per day points (integer 0, 5, or 10): 0 for 0-1 liquid stools, no blood; 5 for up to 2 semi-formed with small blood, or 2-5 liquid; 10 for gross bleeding, or ≥6 liquid, or nocturnal diarrhea. magent does not examine the child. - `well_being` (integer, required): Caller-assigned Hyams 1991 PCDAI patient functioning / general well-being points (integer 0, 5, or 10): 0 no limitation of activities, well; 5 occasional difficulty in maintaining age-appropriate activities; 10 frequent limitation of activities, very poor. magent does not examine the child. - `hematocrit` (number, required): Caller-assigned Hyams 1991 PCDAI hematocrit points (number 0, 2.5, or 5). The paper's age- and sex-specific hematocrit table is applied by the caller. magent does not assign that table. magent does not examine the child. - `esr` (number, required): Caller-assigned Hyams 1991 PCDAI erythrocyte sedimentation rate points (number 0, 2.5, or 5): 0 for ESR <20 mm/h; 2.5 for 20-50; 5 for >50. magent does not assay ESR. magent does not examine the child. - `albumin` (integer, required): Caller-assigned Hyams 1991 PCDAI albumin points (integer 0, 5, or 10): 0 for albumin ≥3.5 g/dL; 5 for 3.1-3.4; 10 for ≤3.0. magent does not assay albumin. magent does not examine the child. - `weight` (integer, required): Caller-assigned Hyams 1991 PCDAI weight points (integer 0, 5, or 10): 0 weight gain or voluntary stable/loss; 5 involuntary stable or weight loss 1-9%; 10 weight loss ≥10%. magent does not examine the child. - `height` (integer, required): Caller-assigned Hyams 1991 PCDAI height points (integer 0, 5, or 10): at diagnosis 0 <1 channel decrease, 5 ≥1 and <2 channel decrease, 10 ≥2 channel decrease; at follow-up 0 height velocity ≥-1 SD, 5 <-1 SD and >-2 SD, 10 ≤-2 SD. magent does not measure height. magent does not examine the child. - `abdomen` (integer, required): Caller-assigned Hyams 1991 PCDAI abdomen points (integer 0, 5, or 10): 0 no tenderness, no mass; 5 tenderness, or mass without tenderness; 10 tenderness, involuntary guarding, definite mass. magent does not examine the child. - `perirectal` (integer, required): Caller-assigned Hyams 1991 PCDAI perirectal disease points (integer 0, 5, or 10): 0 none, asymptomatic tags; 5 1-2 indolent fistula, scant drainage, no tenderness; 10 active fistula, drainage, tenderness, or abscess. magent does not examine the child. - `extra_intestinal` (integer, required): Caller-assigned Hyams 1991 PCDAI extra-intestinal manifestation points (integer 0, 5, or 10): 0 none; 5 one; 10 two or more (fever ≥38.5°C for 3 days over the past week, arthritis, uveitis, erythema nodosum, pyoderma gangrenosum). magent does not examine the child. ## 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/pcdai` 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": [ { "abdomen": "0", "abdominal_pain": "0", "albumin": "0", "esr": "0", "extra_intestinal": "0", "height": "0", "hematocrit": "0", "perirectal": "0", "stools": "0", "weight": "0", "well_being": "0" }, { "abdomen": "0", "abdominal_pain": "0", "albumin": "0", "esr": "0", "extra_intestinal": "0", "height": "0", "hematocrit": "0", "perirectal": "0", "stools": "0", "weight": "0", "well_being": "0" } ] } ``` Human paywall (two-item fixture): https://api.magentlab.com/paywall/bulk/pcdai Example 200: ```json { "count": 2, "path": "/api/calc/pcdai", "items": [ { "components": [ { "value": 0, "factor": "abdominal_pain", "points": 0, "present": true }, { "value": 0, "factor": "stools", "points": 0, "present": true }, { "value": 0, "factor": "well_being", "points": 0, "present": true }, { "value": 0, "factor": "hematocrit", "points": 0, "present": true }, { "value": 0, "factor": "esr", "points": 0, "present": true }, { "value": 0, "factor": "albumin", "points": 0, "present": true }, { "value": 0, "factor": "weight", "points": 0, "present": true }, { "value": 0, "factor": "height", "points": 0, "present": true }, { "value": 0, "factor": "abdomen", "points": 0, "present": true }, { "value": 0, "factor": "perirectal", "points": 0, "present": true }, { "value": 0, "factor": "extra_intestinal", "points": 0, "present": true } ], "weight": 0, "height": 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": "Hyams JS, Ferry GD, Mandel FS, et al.", "doi": "10.1097/00005176-199105000-00001", "id": "hyams-1991", "pmid": "1678008", "source": "J Pediatr Gastroenterol Nutr. 1991;12(4):439-447", "title": "Development and validation of a pediatric Crohn's disease activity index" }, "formula": "pcdai", "formula_expression": "PCDAI = abdominal_pain + stools + well_being + hematocrit + esr + albumin + weight + height + abdomen + perirectal + extra_intestinal; Hyams 1991 caller-assigned item points; hematocrit and esr 0, 2.5, or 5; remaining items 0, 5, or 10; max 100; no published activity bands", "max_score": 100, "score": 0, "abdominal_pain": 0, "well_being": 0, "abdomen": 0, "albumin": 0, "esr": 0, "extra_intestinal": 0, "hematocrit": 0, "perirectal": 0, "stools": 0 }, { "components": [ { "value": 0, "factor": "abdominal_pain", "points": 0, "present": true }, { "value": 0, "factor": "stools", "points": 0, "present": true }, { "value": 0, "factor": "well_being", "points": 0, "present": true }, { "value": 0, "factor": "hematocrit", "points": 0, "present": true }, { "value": 0, "factor": "esr", "points": 0, "present": true }, { "value": 0, "factor": "albumin", "points": 0, "present": true }, { "value": 0, "factor": "weight", "points": 0, "present": true }, { "value": 0, "factor": "height", "points": 0, "present": true }, { "value": 0, "factor": "abdomen", "points": 0, "present": true }, { "value": 0, "factor": "perirectal", "points": 0, "present": true }, { "value": 0, "factor": "extra_intestinal", "points": 0, "present": true } ], "weight": 0, "height": 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": "Hyams JS, Ferry GD, Mandel FS, et al.", "doi": "10.1097/00005176-199105000-00001", "id": "hyams-1991", "pmid": "1678008", "source": "J Pediatr Gastroenterol Nutr. 1991;12(4):439-447", "title": "Development and validation of a pediatric Crohn's disease activity index" }, "formula": "pcdai", "formula_expression": "PCDAI = abdominal_pain + stools + well_being + hematocrit + esr + albumin + weight + height + abdomen + perirectal + extra_intestinal; Hyams 1991 caller-assigned item points; hematocrit and esr 0, 2.5, or 5; remaining items 0, 5, or 10; max 100; no published activity bands", "max_score": 100, "score": 0, "abdominal_pain": 0, "well_being": 0, "abdomen": 0, "albumin": 0, "esr": 0, "extra_intestinal": 0, "hematocrit": 0, "perirectal": 0, "stools": 0 } ] } ``` ## Response fields - `formula` (string): pcdai - `formula_expression` (string): Exact expression used - `score` (number): Hyams 1991 PCDAI points 0-100. Half-points (2.5) occur when hematocrit or esr is 2.5. - `max_score` (integer): Always 100 - `abdominal_pain` (integer): Caller-assigned abdominal pain points 0, 5, or 10 - `stools` (integer): Caller-assigned stools points 0, 5, or 10 - `well_being` (integer): Caller-assigned well-being points 0, 5, or 10 - `hematocrit` (number): Caller-assigned hematocrit points 0, 2.5, or 5 - `esr` (number): Caller-assigned ESR points 0, 2.5, or 5 - `albumin` (integer): Caller-assigned albumin points 0, 5, or 10 - `weight` (integer): Caller-assigned weight points 0, 5, or 10 - `height` (integer): Caller-assigned height points 0, 5, or 10 - `abdomen` (integer): Caller-assigned abdomen points 0, 5, or 10 - `perirectal` (integer): Caller-assigned perirectal points 0, 5, or 10 - `extra_intestinal` (integer): Caller-assigned extra-intestinal points 0, 5, or 10 - `components` (array): Per-item caller-assigned points - `citation` (object): Hyams et al. J Pediatr Gastroenterol Nutr 1991 citation - `disclaimer` (string): Not a medical device ## Example JSON Frozen fixture. Not a live lookup. ```json { "components": [ { "value": 0, "factor": "abdominal_pain", "points": 0, "present": true }, { "value": 0, "factor": "stools", "points": 0, "present": true }, { "value": 0, "factor": "well_being", "points": 0, "present": true }, { "value": 0, "factor": "hematocrit", "points": 0, "present": true }, { "value": 0, "factor": "esr", "points": 0, "present": true }, { "value": 0, "factor": "albumin", "points": 0, "present": true }, { "value": 0, "factor": "weight", "points": 0, "present": true }, { "value": 0, "factor": "height", "points": 0, "present": true }, { "value": 0, "factor": "abdomen", "points": 0, "present": true }, { "value": 0, "factor": "perirectal", "points": 0, "present": true }, { "value": 0, "factor": "extra_intestinal", "points": 0, "present": true } ], "weight": 0, "height": 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": "Hyams JS, Ferry GD, Mandel FS, et al.", "doi": "10.1097/00005176-199105000-00001", "id": "hyams-1991", "pmid": "1678008", "source": "J Pediatr Gastroenterol Nutr. 1991;12(4):439-447", "title": "Development and validation of a pediatric Crohn's disease activity index" }, "formula": "pcdai", "formula_expression": "PCDAI = abdominal_pain + stools + well_being + hematocrit + esr + albumin + weight + height + abdomen + perirectal + extra_intestinal; Hyams 1991 caller-assigned item points; hematocrit and esr 0, 2.5, or 5; remaining items 0, 5, or 10; max 100; no published activity bands", "max_score": 100, "score": 0, "abdominal_pain": 0, "well_being": 0, "abdomen": 0, "albumin": 0, "esr": 0, "extra_intestinal": 0, "hematocrit": 0, "perirectal": 0, "stools": 0 } ``` ## Errors - HTTP 400 `invalid_pcdai`: PCDAI items must be Hyams 1991 caller-assigned points: abdominal_pain, stools, well_being, albumin, weight, height, abdomen, perirectal, and extra_intestinal each 0, 5, or 10; hematocrit and esr each 0, 2.5, or 5. 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 - [CDAI](https://magentlab.com/docs/cdai) — Compute the Best 1976 Crohn's disease activity index from eight caller-assigned variables and return the rounded integer score. Does not return later trial activity bands. - [SES-CD](https://magentlab.com/docs/ses-cd) — Sum four caller-assigned Daperno 2004 SES-CD integers (ulcers, ulcerated_surface, affected_surface, narrowings; each 0-3) in each of five ileocolonic segments (ileum, right_colon, transverse_colon, left_colon, rectum) and return the total (max 60). Does not return activity bands. - [PUCAI](https://magentlab.com/docs/pucai) — Sum six caller-assigned Turner 2007 PUCAI item points and return the published total (max 85) with activity band. - [HBI](https://magentlab.com/docs/harvey-bradshaw) — Sum Harvey 1980 simple-index items (previous-day well-being, abdominal pain, liquid stools, abdominal mass, and one point per listed complication) and return the total. Does not return later remission or activity bands. ## 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.