# DAS28-CRP (28-joint Disease Activity Score) DAS28-CRP Status: LIVE Price: $0.005 USDC `GET /api/calc/das28_crp` HTML: https://magentlab.com/docs/das28-crp Markdown: https://magentlab.com/docs/das28-crp.md Not a medical device. Not a diagnosis, dose, or listing recommendation. ## What it computes Compute the Wells 2009 28-joint Disease Activity Score based on C-reactive protein from caller-assigned TJC28, SJC28, CRP in mg/L, and 0–100 mm general health, including the +0.96 constant, and return DAS28-defined remission when the score is <2.6. ## When to use When an agent already has caller-assigned 28-joint tender and swollen counts, CRP in mg/L, and general health on a 0–100 mm VAS and needs the published Wells 2009 DAS28(CRP), not DAS28-ESR, not SDAI (CRP mg/dL and 0–10 globals), and not CDAI. ## When not to use - Not a medical device and not a rheumatoid arthritis diagnosis or a treatment order. - magent does not count joints or assay CRP. tjc28, sjc28, crp_mg_l, and gh are caller-assigned. CRP is mg/L as published, not mg/dL (SDAI). GH is 0–100 mm VAS, not 0–10 cm. The 0–500 CRP range is a magent clamp. - Computes DAS28(CRP) only, including the +0.96 constant. Does not compute DAS28(ESR). Not SDAI. Not CDAI. - Wells 2009 classifies DAS28-defined remission as a score <2.6. EULAR good/moderate/none response in that paper needs a prior DAS28 and is not this tool. magent does not apply 3.2/5.1 as single-visit activity bands. ## Formula ``` DAS28(CRP) = 0.56*sqrt(tjc28) + 0.28*sqrt(sjc28) + 0.014*gh + 0.36*ln(crp_mg_l+1) + 0.96; Wells 2009; CRP mg/L; GH 0-100 mm VAS; remission DAS28<2.6; not DAS28-ESR; not SDAI; not CDAI; magent does not count joints or assay CRP ``` ## Citation [Validation of the 28-joint Disease Activity Score (DAS28) and European League Against Rheumatism response criteria based on C-reactive protein against disease progression in patients with rheumatoid arthritis, and comparison with the DAS28 based on erythrocyte sedimentation rate](https://doi.org/10.1136/ard.2007.084459) Wells G, Becker JC, Teng J, Dougados M, Schiff M, Smolen J, Aletaha D, van Riel PLCM Ann Rheum Dis. 2009;68(6):954-960 DOI: [10.1136/ard.2007.084459](https://doi.org/10.1136/ard.2007.084459) ## Worked example ### TJC 0, SJC 0, CRP 1 mg/L, GH 0 Given: `crp_mg_l=1, gh=0, sjc28=0, tjc28=0` 1. sqrt(tjc28) and sqrt(sjc28) are 0; 0.014*gh is 0 2. 0.36*ln(1+1) + 0.96 = 0.36*ln(2)+0.96 3. score 1.21 (<2.6), das28_crp_band remission ### Clinical zeros isolate the +0.96 constant Given: `crp_mg_l=0, gh=0, sjc28=0, tjc28=0` 1. ln(0+1) = 0; joint square roots 0; GH term 0 2. score = 0.96 (<2.6), das28_crp_band remission ## Also searched as - DAS28 CRP - DAS28-CRP - 28-joint disease activity score CRP - Wells DAS28 CRP - DAS28 C-reactive protein - RA DAS28 CRP - DAS28 CRP remission ## Parameters - `tjc28` (integer, required): Caller-assigned tender joint count on the 28-joint set (Wells 2009 DAS28-CRP). Integer 0-28. magent does not count joints. - `sjc28` (integer, required): Caller-assigned swollen joint count on the 28-joint set (Wells 2009 DAS28-CRP). Integer 0-28. magent does not count joints. - `crp_mg_l` (number, required): Caller-assigned C-reactive protein in mg/L (Wells 2009; not mg/dL SDAI). Number 0-500 is a magent clamp. magent does not assay CRP. - `gh` (number, required): Caller-assigned general health (patient assessment) on a 0-100 mm VAS (Wells 2009; 0=best, 100=worst). Number 0-100. Not 0-10 cm SDAI PGA. 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/das28_crp` 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": [ { "crp_mg_l": "1", "gh": "0", "sjc28": "0", "tjc28": "0" }, { "crp_mg_l": "1", "gh": "0", "sjc28": "0", "tjc28": "0" } ] } ``` Human paywall (two-item fixture): https://api.magentlab.com/paywall/bulk/das28-crp Example 200: ```json { "count": 2, "path": "/api/calc/das28_crp", "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": "Wells G, Becker JC, Teng J, Dougados M, Schiff M, Smolen J, Aletaha D, van Riel PLCM", "doi": "10.1136/ard.2007.084459", "id": "wells-2009", "pmid": "18490431", "source": "Ann Rheum Dis. 2009;68(6):954-960", "title": "Validation of the 28-joint Disease Activity Score (DAS28) and European League Against Rheumatism response criteria based on C-reactive protein against disease progression in patients with rheumatoid arthritis, and comparison with the DAS28 based on erythrocyte sedimentation rate" }, "formula": "das28_crp", "formula_expression": "DAS28(CRP) = 0.56*sqrt(tjc28) + 0.28*sqrt(sjc28) + 0.014*gh + 0.36*ln(crp_mg_l+1) + 0.96; Wells 2009; CRP mg/L; GH 0-100 mm VAS; remission DAS28<2.6; not DAS28-ESR; not SDAI; not CDAI; magent does not count joints or assay CRP", "score": 1.21, "crp_mg_l": 1.0, "sjc28": 0, "tjc28": 0, "das28_crp_band": "remission", "gh": 0.0 }, { "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": "Wells G, Becker JC, Teng J, Dougados M, Schiff M, Smolen J, Aletaha D, van Riel PLCM", "doi": "10.1136/ard.2007.084459", "id": "wells-2009", "pmid": "18490431", "source": "Ann Rheum Dis. 2009;68(6):954-960", "title": "Validation of the 28-joint Disease Activity Score (DAS28) and European League Against Rheumatism response criteria based on C-reactive protein against disease progression in patients with rheumatoid arthritis, and comparison with the DAS28 based on erythrocyte sedimentation rate" }, "formula": "das28_crp", "formula_expression": "DAS28(CRP) = 0.56*sqrt(tjc28) + 0.28*sqrt(sjc28) + 0.014*gh + 0.36*ln(crp_mg_l+1) + 0.96; Wells 2009; CRP mg/L; GH 0-100 mm VAS; remission DAS28<2.6; not DAS28-ESR; not SDAI; not CDAI; magent does not count joints or assay CRP", "score": 1.21, "crp_mg_l": 1.0, "sjc28": 0, "tjc28": 0, "das28_crp_band": "remission", "gh": 0.0 } ] } ``` ## Response fields - `formula` (string): das28_crp - `formula_expression` (string): Exact expression used - `score` (number): Wells 2009 DAS28(CRP), 2 decimals. 0.56*sqrt(tjc28)+0.28*sqrt(sjc28)+0.014*gh+0.36*ln(crp_mg_l+1)+0.96 - `das28_crp_band` (string): Wells 2009 DAS28-defined remission when score < 2.6; otherwise not_remission. Does not apply EULAR 3.2/5.1 present-score cutoffs as single-visit activity bands. - `tjc28` (integer): Tender 28-joint count used - `sjc28` (integer): Swollen 28-joint count used - `crp_mg_l` (number): CRP in mg/L used - `gh` (number): General health 0-100 mm VAS used - `citation` (object): Wells et al. Ann Rheum Dis 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": "Wells G, Becker JC, Teng J, Dougados M, Schiff M, Smolen J, Aletaha D, van Riel PLCM", "doi": "10.1136/ard.2007.084459", "id": "wells-2009", "pmid": "18490431", "source": "Ann Rheum Dis. 2009;68(6):954-960", "title": "Validation of the 28-joint Disease Activity Score (DAS28) and European League Against Rheumatism response criteria based on C-reactive protein against disease progression in patients with rheumatoid arthritis, and comparison with the DAS28 based on erythrocyte sedimentation rate" }, "formula": "das28_crp", "formula_expression": "DAS28(CRP) = 0.56*sqrt(tjc28) + 0.28*sqrt(sjc28) + 0.014*gh + 0.36*ln(crp_mg_l+1) + 0.96; Wells 2009; CRP mg/L; GH 0-100 mm VAS; remission DAS28<2.6; not DAS28-ESR; not SDAI; not CDAI; magent does not count joints or assay CRP", "score": 1.21, "crp_mg_l": 1.0, "sjc28": 0, "tjc28": 0, "das28_crp_band": "remission", "gh": 0.0 } ``` ## Errors - HTTP 400 `invalid_das28_crp`: DAS28-CRP inputs must match Wells 2009 28-joint counts, CRP mg/L, and 0-100 general health. 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-RA](https://magentlab.com/docs/cdai-ra) — 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. - [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. - [DAS28-ESR](https://magentlab.com/docs/das28-esr) — Compute the Prevoo 1995 28-joint DAS with ESR from caller-assigned tender and swollen 28-joint counts, ESR in mm/h, and patient general health on a 0-100 mm VAS. Returns the published score only. ## 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.