Gout Classification Calculator — ACR/EULAR 2015 Criteria
Apply the validated ACR/EULAR 2015 Gout Classification Criteria: enter clinical findings, serum urate, synovial fluid results, and imaging to calculate the classification score (≥8 = gout).
Entry criterion: ≥1 episode of swelling, pain or tenderness in a peripheral joint or bursa
Synovial fluid MSU crystal analysis (polarised microscopy)
Joint(s) or bursa involved in symptomatic episode
Erythema overlying affected joint (patient-reported or physician-observed)
Can't bear touch or pressure to affected joint
Great difficulty walking or inability to use affected joint
Typical episode duration (pain/swelling resolves within ≤14 days)
Complete resolution between symptomatic episodes
Clinical evidence of tophus
mg/dL
Imaging evidence of urate deposition (US double-contour sign or DECT)
Imaging evidence of gout-related joint damage (plain X-ray erosion)
Score ≥ 8 = classified as gout; range approximately −6 to +23
- 1
Clinical domain score
7Points for joint involvement, episode characteristics, and tophus presence. - 2
Serum urate score
2 - 3
Imaging score
0 - 4
Total classification score
7 + 2 + 0 = 9Score ≥ 8 = classified as gout.
How does this calculator work?
The ACR/EULAR 2015 criteria classify gout when: MSU crystals are found in synovial fluid (sufficient, immediate), OR the classification score ≥8. Points come from joint pattern (0–2), clinical features (+1 each), tophus (+4), serum urate (−4 to +4), negative synovial fluid (−2), and imaging (+4 each). For research and education only.
Formula
How this is calculated
The 2015 ACR/EULAR Gout Classification Criteria use a three-step approach. First, an entry criterion must be met: at least one episode of swelling, pain, or tenderness in a peripheral joint or bursa — without this, the criteria cannot be applied. Second, a sufficient criterion: if monosodium urate (MSU) crystals are identified in synovial fluid by polarised microscopy, the patient is immediately classified as having gout with no need for further scoring. Third, if crystals are not found (or synovial fluid was not tested), a point-based scoring system applies.
The scoring system assigns points across three domains. The clinical domain considers which joints are involved (first MTP joint scores highest at +2), the character of symptomatic episodes (erythema, touch-tenderness, difficulty walking each add +1), the pattern over time (typical duration ≤14 days and complete resolution between attacks each add +1), and evidence of tophus (+4). The laboratory domain scores serum urate measured by the uricase method, ideally outside a flare: levels below 4 mg/dL subtract 4 points while levels ≥10 mg/dL add 4 points; a negative synovial fluid finding subtracts 2 points. The imaging domain adds 4 points each for urate deposition seen on ultrasound or DECT, and for erosion on plain X-ray of the hands or feet.
The criteria were validated in a large international cohort and have a sensitivity of 92% and specificity of 89% when a score ≥8 is used as the classification threshold. These are classification criteria, not diagnostic criteria — they were designed for research enrolment, not bedside clinical decision-making. Clinical judgment, differential diagnosis (septic arthritis, pseudogout, reactive arthritis), and local laboratory reference ranges all remain essential.
Frequently asked questions
Classification criteria define a homogeneous patient group for research. They optimise sensitivity and specificity at the population level. A clinical diagnosis is made by a physician integrating examination findings, history, laboratory results, and response to treatment — including situations where classification criteria are not met. A score below 8 does not rule out gout clinically.
Serum urate can fall to normal or below normal during an acute flare as urate redistributes into tissues. For the most accurate score, measure it during the intercritical period (between attacks), or at least 2–4 weeks after an acute attack resolves. If the value was measured during a flare and is low, it may underestimate the true serum urate level and cause the score to be falsely low.
Not necessarily. The threshold of 8 gives high classification accuracy on average across large populations, but individual cases can be misclassified. Gout can present atypically, especially in women, in patients on diuretics, or early in the disease course before tophi or erosions develop. A rheumatologist's clinical assessment is the gold standard.
Also known as
TG we-Calculate Editorial Team. (2026). Gout Classification Calculator — ACR/EULAR 2015 Criteria [Online calculator]. TG we-Calculate. https://we-calculate.com/calculator/gout-diagnosis-calculator
TG we-Calculate Editorial Team. "Gout Classification Calculator — ACR/EULAR 2015 Criteria." TG we-Calculate. 2026. https://we-calculate.com/calculator/gout-diagnosis-calculator.
TG we-Calculate Editorial Team, "Gout Classification Calculator — ACR/EULAR 2015 Criteria," TG we-Calculate, 2026. [Online]. Available: https://we-calculate.com/calculator/gout-diagnosis-calculator
@misc{wecalculate_gout_diagnosis_calculator, title = {Gout Classification Calculator — ACR/EULAR 2015 Criteria}, author = {{TG we-Calculate Editorial Team}}, howpublished = {\url{https://we-calculate.com/calculator/gout-diagnosis-calculator}}, year = {2026}, note = {TG we-Calculate} }
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