# ACR/EULAR gout classification criteria

ACR/EULAR gout

Status: LIVE
Price: $0.005 USDC
`GET /api/calc/acr_eular_gout`
HTML: https://magentlab.com/docs/acr-eular-gout
Markdown: https://magentlab.com/docs/acr-eular-gout.md

Not a medical device. Not a diagnosis, dose, or listing recommendation.

## What it computes

Apply the 2015 ACR/EULAR gout classification criteria (Neogi Table 2): require the entry episode, classify immediately if MSU crystals are present, otherwise return the Step 3 score (max 23) and whether score ≥8 classifies gout. Not a gout diagnosis.

## When to use

When an agent already has caller-assigned ACR/EULAR 2015 entry, MSU, clinical, urate, synovial, and imaging items and needs the published classification result for research, not a gout diagnosis and not the Janssens 2010 diagnostic rule.

## When not to use

- Not a medical device and not a gout diagnosis. magent does not examine joints or polarizing microscopy.
- Classification criteria for research (Neogi 2015). They apply only when entry_criterion is true (at least one episode of swelling, pain, or tenderness in a peripheral joint or bursa).
- Not the Janssens 2010 gout-rule. MSU-positive synovial fluid is sufficient_msu (Step 2), not the synovial scoring field.
- Serum urate is a caller-supplied uricase-method number. Provide uric_acid_mg_dl (1–20) or uric_acid_umol_l (60–1190), not both. magent does not assay uric acid.

## Formula

```
ACR/EULAR 2015 gout classification (Neogi Table 2): entry (episode of swelling, pain, or tenderness in a peripheral joint or bursa) required; sufficient MSU in a symptomatic joint/bursa or tophus classifies without score ≥8; else score ≥8 classifies. Score = pattern (other 0, ankle_midfoot 1, mtp1 2) + characteristics 0-3 + time_course (none 0, one_typical 1, recurrent 2) + tophus true 4 + serum urate (<4 mg/dL or <0.24 mmol/L −4; ≥4–<6 or ≥0.24–<0.36 0; 6–<8 or 0.36–<0.48 2; 8–<10 or 0.48–<0.60 3; ≥10 or ≥0.60 4) + synovial (not_done 0, msu_negative −2) + imaging_urate present 4 + imaging_erosion present 4; max 23. Not a diagnosis. Not Janssens 2010
```

## Citation

[2015 Gout Classification Criteria: an American College of Rheumatology/European League Against Rheumatism collaborative initiative](https://doi.org/10.1002/art.39254)
Neogi T, Jansen TLTA, Dalbeth N, Fransen J, Schumacher HR, Berendsen D, Brown M, Choi H, Edwards NL, Janssens HJEM, Lioté F, Naden RP, Nuki G, Ogdie A, Perez-Ruiz F, Saag K, Singh JA, Sundy JS, Tausche AK, Vazquez-Mellado J, Yarows SA, Taylor WJ
Arthritis Rheumatol. 2015;67(10):2557-2568
DOI: [10.1002/art.39254](https://doi.org/10.1002/art.39254)

## Worked example

### Entry met, no MSU, all domains zero, urate 5.0 mg/dL

Given: `characteristics=0, entry_criterion=true, imaging_erosion=absent_or_not_done, imaging_urate=absent_or_not_done, pattern=other, sufficient_msu=false, synovial=not_done, time_course=none, tophus=false, uric_acid_mg_dl=5.0`

1. entry_criterion true; sufficient_msu false
2. pattern other 0 + characteristics 0 + time_course none 0 + tophus false 0 + urate 5.0 (≥4 and <6) 0 + synovial not_done 0 + imaging absent 0
3. Score = 0 (max 23); classified_gout false; gout_band not_classified


### Sufficient MSU classifies with score 0

Given: `characteristics=0, entry_criterion=true, imaging_erosion=absent_or_not_done, imaging_urate=absent_or_not_done, pattern=other, sufficient_msu=true, synovial=not_done, time_course=none, tophus=false, uric_acid_mg_dl=5.0`

1. sufficient_msu true (MSU crystals in a symptomatic joint/bursa or tophus)
2. Step 3 domains remain zero; score 0
3. classified_gout true without requiring score ≥8; gout_band classified


### Score 11 classifies without MSU

Given: `characteristics=3, entry_criterion=true, imaging_erosion=absent_or_not_done, imaging_urate=absent_or_not_done, pattern=mtp1, sufficient_msu=false, synovial=not_done, time_course=recurrent, tophus=true, uric_acid_mg_dl=5.0`

1. mtp1 2 + characteristics 3 + recurrent 2 + tophus 4; urate 5.0 scores 0
2. Score = 11 ≥8; classified_gout true; gout_band classified


### Maximum score 23

Given: `characteristics=3, entry_criterion=true, imaging_erosion=present, imaging_urate=present, pattern=mtp1, sufficient_msu=false, synovial=not_done, time_course=recurrent, tophus=true, uric_acid_mg_dl=10.0`

1. mtp1 2 + characteristics 3 + recurrent 2 + tophus 4 + urate ≥10 4 + imaging_urate 4 + imaging_erosion 4; synovial not_done 0
2. Score = 23 (max 23); classified_gout true


## Also searched as

- ACR EULAR gout
- 2015 gout classification criteria
- Neogi 2015 gout
- ACR/EULAR gout score
- MSU crystal gout classification
- gout classification criteria
- ACR EULAR 2015 gout
- not Janssens gout rule

## Parameters

- `entry_criterion` (boolean, required): Must be true. ACR/EULAR 2015 entry: at least one episode of swelling, pain, or tenderness in a peripheral joint or bursa. false is invalid. magent does not examine joints.
- `sufficient_msu` (boolean, required): Presence of MSU crystals in a symptomatic joint or bursa (synovial fluid) or tophus (Neogi 2015 Step 2). true classifies gout without requiring score ≥8. magent does not perform polarizing microscopy.
- `pattern` (string, required): Pattern of joint/bursa involvement ever, monoarticular or oligoarticular unless other (Neogi 2015). other (joints/bursa other than ankle, midfoot, or 1st MTP, or only as part of a polyarticular presentation) scores 0. ankle_midfoot (ankle or midfoot without 1st MTP) scores 1. mtp1 (1st MTP) scores 2. magent does not examine joints.
- `characteristics` (integer, required): Count (0-3) of symptomatic-episode characteristics ever: erythema overlying the affected joint; cannot bear touch or pressure; great difficulty walking or inability to use the affected joint (Neogi 2015). Points equal the count. magent does not examine joints.
- `time_course` (string, required): Time course of episode(s) ever (Neogi 2015). A typical episode has ≥2 of: time to maximum pain <24 h; resolution ≤14 days; complete resolution between episodes. none scores 0; one_typical scores 1; recurrent scores 2. magent does not take a history.
- `tophus` (boolean, required): Clinical evidence of tophus: draining or chalk-like subcutaneous nodule under transparent skin, often with overlying vascularity, in typical locations (joints, ears, olecranon bursae, finger pads, tendons e.g. Achilles) (Neogi 2015). true scores 4; false scores 0. magent does not examine joints.
- `uric_acid_mg_dl` (number, optional): Highest serum urate in mg/dL (uricase method; 1-20). Provide this or uric_acid_umol_l, not both. <4 scores −4; ≥4 and <6 scores 0; 6–<8 scores 2; 8–<10 scores 3; ≥10 scores 4. magent does not assay uric acid.
- `uric_acid_umol_l` (number, optional): Highest serum urate in µmol/L (uricase method; 60-1190). Provide this or uric_acid_mg_dl, not both. mmol/L = µmol/L / 1000. <0.24 scores −4; ≥0.24 and <0.36 scores 0; 0.36–<0.48 scores 2; 0.48–<0.60 scores 3; ≥0.60 scores 4. magent does not assay uric acid.
- `synovial` (string, required): Synovial fluid of a symptomatic (ever) joint/bursa, trained observer (Neogi 2015). not_done scores 0; msu_negative scores −2. MSU-positive is sufficient_msu, not this field. magent does not perform polarizing microscopy.
- `imaging_urate` (string, required): Imaging evidence of urate deposition (ultrasound double-contour or DECT urate) in a symptomatic (ever) joint/bursa (Neogi 2015). present scores 4. If imaging is not available, absent_or_not_done scores 0. magent does not read imaging.
- `imaging_erosion` (string, required): Conventional radiograph of hands and/or feet with ≥1 gout-related erosion (cortical break with sclerotic margin and overhanging edge; excludes DIP joints and gull-wing) (Neogi 2015). present scores 4; absent_or_not_done scores 0. magent does not read radiographs.

## 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/acr_eular_gout`
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": [
    {
      "characteristics": "0",
      "entry_criterion": "true",
      "imaging_erosion": "absent_or_not_done",
      "imaging_urate": "absent_or_not_done",
      "pattern": "other",
      "sufficient_msu": "false",
      "synovial": "not_done",
      "time_course": "none",
      "tophus": "false",
      "uric_acid_mg_dl": "5.0"
    },
    {
      "characteristics": "0",
      "entry_criterion": "true",
      "imaging_erosion": "absent_or_not_done",
      "imaging_urate": "absent_or_not_done",
      "pattern": "other",
      "sufficient_msu": "false",
      "synovial": "not_done",
      "time_course": "none",
      "tophus": "false",
      "uric_acid_mg_dl": "5.0"
    }
  ]
}
```

Human paywall (two-item fixture): https://api.magentlab.com/paywall/bulk/acr-eular-gout

Example 200:

```json
{
  "count": 2,
  "path": "/api/calc/acr_eular_gout",
  "items": [
    {
      "components": [
        {
          "value": "other",
          "factor": "pattern",
          "points": 0,
          "present": true
        },
        {
          "value": 0,
          "factor": "characteristics",
          "points": 0,
          "present": true
        },
        {
          "value": "none",
          "factor": "time_course",
          "points": 0,
          "present": true
        },
        {
          "value": false,
          "factor": "tophus",
          "points": 0,
          "present": true
        },
        {
          "value": 5.0,
          "factor": "serum_urate",
          "points": 0,
          "present": true
        },
        {
          "value": "not_done",
          "factor": "synovial",
          "points": 0,
          "present": true
        },
        {
          "value": "absent_or_not_done",
          "factor": "imaging_urate",
          "points": 0,
          "present": true
        },
        {
          "value": "absent_or_not_done",
          "factor": "imaging_erosion",
          "points": 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": "Neogi T, Jansen TLTA, Dalbeth N, Fransen J, Schumacher HR, Berendsen D, Brown M, Choi H, Edwards NL, Janssens HJEM, Lioté F, Naden RP, Nuki G, Ogdie A, Perez-Ruiz F, Saag K, Singh JA, Sundy JS, Tausche AK, Vazquez-Mellado J, Yarows SA, Taylor WJ",
        "doi": "10.1002/art.39254",
        "id": "neogi-2015",
        "pmid": "26352873",
        "source": "Arthritis Rheumatol. 2015;67(10):2557-2568",
        "title": "2015 Gout Classification Criteria: an American College of Rheumatology/European League Against Rheumatism collaborative initiative"
      },
      "formula": "acr_eular_gout",
      "formula_expression": "ACR/EULAR 2015 gout classification (Neogi Table 2): entry (episode of swelling, pain, or tenderness in a peripheral joint or bursa) required; sufficient MSU in a symptomatic joint/bursa or tophus classifies without score ≥8; else score ≥8 classifies. Score = pattern (other 0, ankle_midfoot 1, mtp1 2) + characteristics 0-3 + time_course (none 0, one_typical 1, recurrent 2) + tophus true 4 + serum urate (<4 mg/dL or <0.24 mmol/L −4; ≥4–<6 or ≥0.24–<0.36 0; 6–<8 or 0.36–<0.48 2; 8–<10 or 0.48–<0.60 3; ≥10 or ≥0.60 4) + synovial (not_done 0, msu_negative −2) + imaging_urate present 4 + imaging_erosion present 4; max 23. Not a diagnosis. Not Janssens 2010",
      "max_score": 23,
      "score": 0,
      "classified_gout": false,
      "gout_band": "not_classified",
      "sufficient_criterion": false
    },
    {
      "components": [
        {
          "value": "other",
          "factor": "pattern",
          "points": 0,
          "present": true
        },
        {
          "value": 0,
          "factor": "characteristics",
          "points": 0,
          "present": true
        },
        {
          "value": "none",
          "factor": "time_course",
          "points": 0,
          "present": true
        },
        {
          "value": false,
          "factor": "tophus",
          "points": 0,
          "present": true
        },
        {
          "value": 5.0,
          "factor": "serum_urate",
          "points": 0,
          "present": true
        },
        {
          "value": "not_done",
          "factor": "synovial",
          "points": 0,
          "present": true
        },
        {
          "value": "absent_or_not_done",
          "factor": "imaging_urate",
          "points": 0,
          "present": true
        },
        {
          "value": "absent_or_not_done",
          "factor": "imaging_erosion",
          "points": 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": "Neogi T, Jansen TLTA, Dalbeth N, Fransen J, Schumacher HR, Berendsen D, Brown M, Choi H, Edwards NL, Janssens HJEM, Lioté F, Naden RP, Nuki G, Ogdie A, Perez-Ruiz F, Saag K, Singh JA, Sundy JS, Tausche AK, Vazquez-Mellado J, Yarows SA, Taylor WJ",
        "doi": "10.1002/art.39254",
        "id": "neogi-2015",
        "pmid": "26352873",
        "source": "Arthritis Rheumatol. 2015;67(10):2557-2568",
        "title": "2015 Gout Classification Criteria: an American College of Rheumatology/European League Against Rheumatism collaborative initiative"
      },
      "formula": "acr_eular_gout",
      "formula_expression": "ACR/EULAR 2015 gout classification (Neogi Table 2): entry (episode of swelling, pain, or tenderness in a peripheral joint or bursa) required; sufficient MSU in a symptomatic joint/bursa or tophus classifies without score ≥8; else score ≥8 classifies. Score = pattern (other 0, ankle_midfoot 1, mtp1 2) + characteristics 0-3 + time_course (none 0, one_typical 1, recurrent 2) + tophus true 4 + serum urate (<4 mg/dL or <0.24 mmol/L −4; ≥4–<6 or ≥0.24–<0.36 0; 6–<8 or 0.36–<0.48 2; 8–<10 or 0.48–<0.60 3; ≥10 or ≥0.60 4) + synovial (not_done 0, msu_negative −2) + imaging_urate present 4 + imaging_erosion present 4; max 23. Not a diagnosis. Not Janssens 2010",
      "max_score": 23,
      "score": 0,
      "classified_gout": false,
      "gout_band": "not_classified",
      "sufficient_criterion": false
    }
  ]
}
```

## Response fields

- `formula` (string): acr_eular_gout
- `formula_expression` (string): Neogi 2015 ACR/EULAR gout classification expression
- `score` (number): Step 3 clinical score (may be negative; min −6, max 23). Always computed, including when sufficient_msu is true.
- `max_score` (integer): Always 23
- `classified_gout` (boolean): true iff sufficient_msu is true or score ≥8. Classification criteria for research, not a gout diagnosis.
- `sufficient_criterion` (boolean): Echo of sufficient_msu (Neogi 2015 Step 2)
- `gout_band` (string): classified when classified_gout is true; not_classified otherwise. Not a gout diagnosis.
- `components` (array): Per-domain Neogi 2015 points
- `citation` (object): Neogi 2015 Arthritis Rheumatol citation
- `disclaimer` (string): Not-a-device notice

## Example JSON

Frozen fixture. Not a live lookup.

```json
{
  "components": [
    {
      "value": "other",
      "factor": "pattern",
      "points": 0,
      "present": true
    },
    {
      "value": 0,
      "factor": "characteristics",
      "points": 0,
      "present": true
    },
    {
      "value": "none",
      "factor": "time_course",
      "points": 0,
      "present": true
    },
    {
      "value": false,
      "factor": "tophus",
      "points": 0,
      "present": true
    },
    {
      "value": 5.0,
      "factor": "serum_urate",
      "points": 0,
      "present": true
    },
    {
      "value": "not_done",
      "factor": "synovial",
      "points": 0,
      "present": true
    },
    {
      "value": "absent_or_not_done",
      "factor": "imaging_urate",
      "points": 0,
      "present": true
    },
    {
      "value": "absent_or_not_done",
      "factor": "imaging_erosion",
      "points": 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": "Neogi T, Jansen TLTA, Dalbeth N, Fransen J, Schumacher HR, Berendsen D, Brown M, Choi H, Edwards NL, Janssens HJEM, Lioté F, Naden RP, Nuki G, Ogdie A, Perez-Ruiz F, Saag K, Singh JA, Sundy JS, Tausche AK, Vazquez-Mellado J, Yarows SA, Taylor WJ",
    "doi": "10.1002/art.39254",
    "id": "neogi-2015",
    "pmid": "26352873",
    "source": "Arthritis Rheumatol. 2015;67(10):2557-2568",
    "title": "2015 Gout Classification Criteria: an American College of Rheumatology/European League Against Rheumatism collaborative initiative"
  },
  "formula": "acr_eular_gout",
  "formula_expression": "ACR/EULAR 2015 gout classification (Neogi Table 2): entry (episode of swelling, pain, or tenderness in a peripheral joint or bursa) required; sufficient MSU in a symptomatic joint/bursa or tophus classifies without score ≥8; else score ≥8 classifies. Score = pattern (other 0, ankle_midfoot 1, mtp1 2) + characteristics 0-3 + time_course (none 0, one_typical 1, recurrent 2) + tophus true 4 + serum urate (<4 mg/dL or <0.24 mmol/L −4; ≥4–<6 or ≥0.24–<0.36 0; 6–<8 or 0.36–<0.48 2; 8–<10 or 0.48–<0.60 3; ≥10 or ≥0.60 4) + synovial (not_done 0, msu_negative −2) + imaging_urate present 4 + imaging_erosion present 4; max 23. Not a diagnosis. Not Janssens 2010",
  "max_score": 23,
  "score": 0,
  "classified_gout": false,
  "gout_band": "not_classified",
  "sufficient_criterion": false
}
```

## Errors

- HTTP 400 `invalid_acr_eular_gout`: entry_criterion must be true; pattern must be other, ankle_midfoot, or mtp1; characteristics an integer 0-3; time_course none, one_typical, or recurrent; synovial not_done or msu_negative; imaging_urate and imaging_erosion absent_or_not_done or present (Neogi 2015 ACR/EULAR gout). Returned before settlement; you are not charged.
- HTTP 400 `invalid_flag`: boolean clinical flags must be true or false Returned before settlement; you are not charged.
- HTTP 400 `invalid_uric_acid`: uric_acid_mg_dl (1-20) or uric_acid_umol_l (60-1190) is required, not both. 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

- [Gout rule](https://magentlab.com/docs/gout-rule) — Sum the Janssens 2010 diagnostic-rule points for acute gouty arthritis without joint-fluid analysis and return low (≤4), intermediate (4.5–7.5), or high (≥8).

## 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.