Table 2

The ACR/EULAR gout classification criteria*

Step 1: Entry criterion (only apply criteria below to those meeting this entry criterion)At least 1 episode of swelling, pain, or tenderness in a peripheral joint or bursa
Step 2: Sufficient criterion (if met, can classify as gout without applying criteria below)Presence of MSU crystals in a symptomatic joint or bursa (ie, in synovial fluid) or tophus
Step 3: Criteria (to be used if sufficient criterion not met)
 Pattern of joint/bursa involvement during symptomatic episode(s) everAnkle or mid-foot (as part of monoarticular or oligoarticular episode without involvement of the first metatarsophalangeal joint1
Involvement of the first metatarsophalangeal joint (as part of monoarticular or oligoarticular episode)2
 Characteristics of symptomatic episode(s) ever
  ▸ Erythema overlying affected joint (patient-reported or physician-observed)
  ▸ Can't bear touch or pressure to affected joint
  ▸ Great difficulty with walking or inability to use affected joint
One characteristic
Two characteristics
Three characteristics
 Time course of episode(s) ever
  Presence (ever) of ≥2, irrespective of anti-inflammatory treatment:    ▸ Time to maximal pain <24 h    ▸ Resolution of symptoms in ≤14 days    ▸ Complete resolution (to baseline level) between symptomatic episodes
One typical episode
Recurrent typical episodes
 Clinical evidence of tophus
   Draining or chalk-like subcutaneous nodule under transparent skin, often with overlying vascularity, located in typical locations: joints, ears, olecranon bursae, finger pads, tendons (eg, Achilles)
 Serum urate: Measured by the uricase method.    Ideally should be scored at a time when the patient was not receiving urate-lowering treatment and it was >4 weeks from the start of an episode (ie, during the intercritical period); if practicable, retest under those conditions. The highest value irrespective of timing should be scored<4 mg/dL (<0.24 mmol/L)†
6–<8 mg/dL (0.36–<0.48 mmol/L)
8–<10 mg/dL (0.48–<0.60 mmol/L)
≥10 mg/dL (≥0.60 mmol/L)
 Synovial fluid analysis of a symptomatic (ever)    joint or bursa (should be assessed by a trained observer)‡MSU negative−2
 Imaging evidence of urate deposition in symptomatic (ever) joint or bursa: ultrasound evidence of double-contour sign¶ or DECT demonstrating urate deposition**Present (either modality)4
 Imaging evidence of gout-related joint damage: conventional radiography of the hands and/or feet demonstrates at least 1 erosion††Present4
  • *A web-based calculator can be accessed at:, and through the American College of Rheumatology (ACR) and European League Against Rheumatism (EULAR) web sites.

  • †Symptomatic episodes are periods of symptoms that include any swelling, pain, and/or tenderness in a peripheral joint or bursa.

  • ‡If serum urate level is <4 mg/dL (<0.24 mmoles/liter), subtract 4 points; if serum urate level is ≥4 mg/dL – >6 mg/dL (≥0.24 – <0.36 mmoles/liter), score this item as 0.

  • §If polarizing microscopy of synovial fluid from a symptomatic (ever) joint or bursa by a trained examiner fails to show monosodium urate monohydrate (MSU) crystals, subtract 2 points. If synovial fluid was not assessed, score this item as 0.

  • ¶If imaging is not available, score these items as 0. #Hyperechoic irregular enhancement over the surface of the hyaline cartilage that is independent of the insonation angle of the ultrasound beam (note: false-positive double-contour sign [artifact] may appear at the cartilage surface but should disappear with a change in the insonation angle of the probe).31 ,32

  • **Presence of color-coded urate at articular or periarticular sites. Images should be acquired using a dual-energy computed tomography (DECT) scanner, with data acquired at 80 kV and 140 kV and analyzed using gout-specific software with a 2-material decomposition algorithm that color-codes urate.33 A positive scan is defined as the presence of color-coded urate at articular or periarticular sites. Nailbed, submillimeter, skin, motion, beam hardening, and vascular artifacts should not be interpreted as DECT evidence of urate deposition.34

  • ††Erosion is defined as a cortical break with sclerotic margin and overhanging edge, excluding distal interphalangeal joints and gull wing appearance.