# Clinical Disease Activity Index (CDAI) for RA CDAI-RA Status: LIVE Price: $0.005 USDC `GET /api/calc/cdai_ra` HTML: https://magentlab.com/docs/cdai-ra Markdown: https://magentlab.com/docs/cdai-ra.md Not a medical device. Not a diagnosis, dose, or listing recommendation. ## What it computes Sum caller-assigned 28-joint swollen and tender counts and 0–10 cm patient and evaluator globals and return the Aletaha 2005 Clinical Disease Activity Index. Does not add CRP and does not return activity-state cutoffs. ## When to use When an agent already has caller-assigned 28-joint swollen and tender counts and 0–10 cm patient and evaluator globals and needs the published CDAI sum (SJC+TJC+PGA+EGA), not SDAI, not Crohn's CDAI, and not later unofficial activity-state cutoffs. ## When not to use - Not a medical device and not a rheumatoid arthritis diagnosis or a treatment order. - magent does not count joints. sjc28, tjc28, pga, and ega are caller-assigned. PGA and EGA are centimetres on a 0–10 VAS as published. - CDAI is SJC28 + TJC28 + PGA + EGA. It does not include CRP. Not SDAI. Not Crohn's CDAI. - Aletaha 2005 Arthritis Res Ther (ar1740) validates the sum against DAS28, SDAI, and HAQ. It does not publish activity-state cutoffs. magent returns score and max_score only. ## Formula ``` CDAI = sjc28 + tjc28 + pga + ega; Aletaha 2005 Arthritis Res Ther (ar1740); PGA and EGA in cm on a 0-10 VAS; half points allowed; not integer-rounded; max 76; magent does not count joints; not SDAI; not Crohn's CDAI; no published activity-state cutoffs ``` ## Citation [Acute phase reactants add little to composite disease activity indices for rheumatoid arthritis: validation of a clinical activity score](https://doi.org/10.1186/ar1740) Aletaha D, Nell VPK, Stamm T, et al. Arthritis Res Ther. 2005;7(4):R796-R806 DOI: [10.1186/ar1740](https://doi.org/10.1186/ar1740) ## Worked example ### Clinical zeros Given: `ega=0, pga=0, sjc28=0, tjc28=0` 1. sjc28 0 + tjc28 0 + pga 0 + ega 0 2. score = 0 (max 76). No activity-state cutoff. ### Half points are not integer-rounded Given: `ega=0.25, pga=1.5, sjc28=0, tjc28=0` 1. pga 1.5 + ega 0.25; joint counts 0 2. score = 1.75 (not 2). No activity-state cutoff. ## Also searched as - Clinical Disease Activity Index - CDAI RA - Aletaha CDAI - rheumatoid arthritis CDAI - CDAI without CRP - RA clinical disease activity ## Parameters - `sjc28` (integer, required): Caller-assigned swollen joint count on the 28-joint set (Aletaha 2005 CDAI). Integer 0-28. magent does not count joints. - `tjc28` (integer, required): Caller-assigned tender joint count on the 28-joint set (Aletaha 2005 CDAI). Integer 0-28. magent does not count joints. - `pga` (number, required): Caller-assigned patient global assessment on a 0-10 cm VAS (Aletaha 2005 CDAI). Number 0-10. magent does not examine the patient. - `ega` (number, required): Caller-assigned evaluator global assessment on a 0-10 cm VAS (Aletaha 2005 CDAI). Number 0-10. magent does not examine 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/cdai_ra` 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": [ { "ega": "0", "pga": "0", "sjc28": "0", "tjc28": "0" }, { "ega": "0", "pga": "0", "sjc28": "0", "tjc28": "0" } ] } ``` Human paywall (two-item fixture): https://api.magentlab.com/paywall/bulk/cdai-ra Example 200: ```json { "count": 2, "path": "/api/calc/cdai_ra", "items": [ { "components": [ { "value": 0, "factor": "sjc28", "points": 0, "present": true }, { "value": 0, "factor": "tjc28", "points": 0, "present": true }, { "value": 0.0, "factor": "pga", "points": 0.0, "present": true }, { "value": 0.0, "factor": "ega", "points": 0.0, "present": true } ], "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": "Aletaha D, Nell VPK, Stamm T, et al.", "doi": "10.1186/ar1740", "id": "aletaha-2005-cdai", "pmid": "15987481", "source": "Arthritis Res Ther. 2005;7(4):R796-R806", "title": "Acute phase reactants add little to composite disease activity indices for rheumatoid arthritis: validation of a clinical activity score" }, "formula": "cdai_ra", "formula_expression": "CDAI = sjc28 + tjc28 + pga + ega; Aletaha 2005 Arthritis Res Ther (ar1740); PGA and EGA in cm on a 0-10 VAS; half points allowed; not integer-rounded; max 76; magent does not count joints; not SDAI; not Crohn's CDAI; no published activity-state cutoffs", "max_score": 76, "score": 0.0, "ega": 0.0, "pga": 0.0, "sjc28": 0, "tjc28": 0 }, { "components": [ { "value": 0, "factor": "sjc28", "points": 0, "present": true }, { "value": 0, "factor": "tjc28", "points": 0, "present": true }, { "value": 0.0, "factor": "pga", "points": 0.0, "present": true }, { "value": 0.0, "factor": "ega", "points": 0.0, "present": true } ], "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": "Aletaha D, Nell VPK, Stamm T, et al.", "doi": "10.1186/ar1740", "id": "aletaha-2005-cdai", "pmid": "15987481", "source": "Arthritis Res Ther. 2005;7(4):R796-R806", "title": "Acute phase reactants add little to composite disease activity indices for rheumatoid arthritis: validation of a clinical activity score" }, "formula": "cdai_ra", "formula_expression": "CDAI = sjc28 + tjc28 + pga + ega; Aletaha 2005 Arthritis Res Ther (ar1740); PGA and EGA in cm on a 0-10 VAS; half points allowed; not integer-rounded; max 76; magent does not count joints; not SDAI; not Crohn's CDAI; no published activity-state cutoffs", "max_score": 76, "score": 0.0, "ega": 0.0, "pga": 0.0, "sjc28": 0, "tjc28": 0 } ] } ``` ## Response fields - `formula` (string): cdai_ra - `formula_expression` (string): Exact expression used - `score` (number): CDAI sum sjc28 + tjc28 + pga + ega. Not integer-rounded; half points allowed. Theoretical max 76. No activity-state cutoffs. - `max_score` (integer): Always 76 (28+28+10+10) - `sjc28` (integer): Swollen 28-joint count used - `tjc28` (integer): Tender 28-joint count used - `pga` (number): Patient global 0-10 cm VAS used - `ega` (number): Evaluator global 0-10 cm VAS used - `components` (array): Per-variable points - `citation` (object): Aletaha et al. Arthritis Res Ther 2005 citation - `disclaimer` (string): Not-a-device notice ## Example JSON Frozen fixture. Not a live lookup. ```json { "components": [ { "value": 0, "factor": "sjc28", "points": 0, "present": true }, { "value": 0, "factor": "tjc28", "points": 0, "present": true }, { "value": 0.0, "factor": "pga", "points": 0.0, "present": true }, { "value": 0.0, "factor": "ega", "points": 0.0, "present": true } ], "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": "Aletaha D, Nell VPK, Stamm T, et al.", "doi": "10.1186/ar1740", "id": "aletaha-2005-cdai", "pmid": "15987481", "source": "Arthritis Res Ther. 2005;7(4):R796-R806", "title": "Acute phase reactants add little to composite disease activity indices for rheumatoid arthritis: validation of a clinical activity score" }, "formula": "cdai_ra", "formula_expression": "CDAI = sjc28 + tjc28 + pga + ega; Aletaha 2005 Arthritis Res Ther (ar1740); PGA and EGA in cm on a 0-10 VAS; half points allowed; not integer-rounded; max 76; magent does not count joints; not SDAI; not Crohn's CDAI; no published activity-state cutoffs", "max_score": 76, "score": 0.0, "ega": 0.0, "pga": 0.0, "sjc28": 0, "tjc28": 0 } ``` ## Errors - HTTP 400 `invalid_cdai_ra`: sjc28 and tjc28 must be integers 0–28; pga and ega numbers 0–10 cm (Aletaha 2005 CDAI = SJC + TJC + PGA + EGA). 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 - [SDAI](https://magentlab.com/docs/sdai) — Sum caller-assigned 28-joint swollen and tender counts, 0–10 cm patient and evaluator globals, and CRP in mg/dL, and return the Aletaha 2005 SDAI with the newly proposed activity state. - [CASPAR](https://magentlab.com/docs/caspar) — Apply the Taylor 2006 CASPAR classification criteria for psoriatic arthritis: require established inflammatory articular disease, then return the published point total (max 8) and whether score ≥3 classifies psoriatic arthritis. Not a diagnosis. - [Leiden UA rule](https://magentlab.com/docs/leiden-arthritis) — Sum the van der Helm-van Mil 2007 simplified Leiden prediction score for recent-onset undifferentiated arthritis and return the paper’s ≤6 / 6–8 / ≥8 decision band. ## 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.