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    Acute Gout Diagnosis Rule

    Risk stratifies for gout vs non-gout arthritis and helps determine which patients benefit most from joint aspiration.
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    Why Use

    A patient with a new monoarthritis.

    • The Acute Gout Diagnosis Rule helps reduce unnecessary joint aspirations by predicting gout risk based on clinical criteria.
    • It was originally studied and validated in two primary care cohorts in Europe, so may not be as applicable in non-European populations.
    • Score correlates with likelihood of gout, with scores ≤4 unlikely to be gout, scores ≥8 likely to be gout, and 4-8 indeterminate.
    • False positives in the studies were mostly “unknown arthritis” and management typically did not change. Septic arthritis was not seen in these high scores.
    • Low scores are unlikely to be gout and other causes of gout should be considered, including pseudogout, septic arthritis, reactive arthritis, psoriatic, rheumatoid, or osteoarthritis.
    • The Acute Gout Diagnosis Rule can help rule in or rule out the diagnosis of gout, and help determine which patients benefit from joint aspiration and which could be treated empirically for gout specifically.
    • The rule also out-performs clinician gestalt and improves diagnostic accuracy.
    About the Creator
    Dr. Hein Janssens

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    Advice

    The authors provide several recommendations based on a patient's score:

    • ≤4 points: Unlikely gout. Other causes of monoarthritis should be considered, for example: pseudogout, septic arthritis, reactive arthritis, psoriatic, rheumatoid, or osteoarthritis.
    • 4-8 points: These patients are most likely to benefit from joint aspiration and fluid analysis for urate crystals.
    • ≥8 points: Gouty arthritis is very likely, and empiric gout medications can be started as opposed to more generic arthritis treatments (like NSAIDs).

    Management

    • Gout flares are often treated with some combination of steroids, NSAIDS (classically, indomethacin), opioids for extreme pain, and colchicine, depending on a patient's age and other risk factors for complications.
    • After the initial flare, patients may benefit from urate-lowering therapies like allopurinol.

    Formula

    Addition of selected points, see below.

    Facts & Figures

    Score interpretation:

    Score Prevalence of gout
    ≤4 points 2.2%
    >4 and <8 points 31.2%
    ≥8 points 80.4%

    Midrange scores (>4 to <8) are unable to rule out or rule in gout diagnosis. Further laboratory testing is suggested by the original study, using analysis of synovial fluid from the affected joint for the presence of monosodium urate (MSU) crystals.

    Evidence Appraisal

    • As mentioned above, this rule was developed and validated twice in Europe, and may be less applicable to non-European populations.
    • The AUC for the receiver operator curves from the original and validation studies ranged from 0.86-0.89, suggesting overall good diagnostic accuracy.
    • The rule improves on clinician gestalt: “PPV of the clinical diagnosis may improve from 0.64 to 0.87 and the NPV from 0.87 to 0.95.”
    • The authors note that even the “gold standard” of monosodium urate crystals in fluid analysis is falsely negative about 5% of the time, suggesting that some of the “false positive” patients in the study with an “unknown arthritis” may have actually had gout as well.
    Dr. Hein Janssens

    About the Creator

    Hein J. E. M. Janssens, MD, is a researcher in the Department of Primary and Community Care, Radboud University Nijmegen Medical Center, in Nijmegen, the Netherlands. He practices in the fields of internal medicine, primary care and rheumatology.

    To view Dr. Hein Janssens's publications, visit PubMed