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Am Fam Physician. 2016;93(4):256-258

Original Article: Differential Diagnosis of Polyarticular Arthritis

Issue Date: July 1, 2015

to the editor: We appreciate this comprehensive and engaging article. We agree that joint fluid analysis is the preferred method for the diagnosis of gout, and that uric acid measurements are not beneficial when interpreted in isolation. However, as mentioned in an earlier article on gout published in American Family Physician,1 a diagnostic tool was developed in 2010 to aid primary care physicians in diagnosing the condition without the need for joint aspirate.2 This tool uses seven independent criteria, including serum uric acid level, to determine the likelihood that a patient is experiencing a gouty flare (Table 1).3 It was validated in a 2015 study, in which scores of 4 or less demonstrated a negative predictive value of 0.95, whereas scores of 8 or more had a positive predictive value of 0.87.3 Although scores between 4 and 8 may warrant joint aspiration and fluid analysis, this diagnostic tool may prove clinically useful when a gouty cause is suspected in patients with arthritic symptoms and the capability of joint aspiration does not exist or is impractical.

Previous self-reported arthritis attack2
Onset within 1 day0.5
Joint redness1
Involvement of first metatarsophalangeal joint2.5
Hypertension or at least one of the following conditions: angina pectoris, cerebrovascular accident, heart failure, myocardial infarction, peripheral vascular disease, transient ischemic attack1.5
Serum uric acid level > 5.88 mg per dL (350 μmol per L)3.5
Total____ (out of 13 possible points)

The views expressed in this article are those of the authors and do not necessarily reflect the official policy or position of the Department of the Army, Department of the Air Force, Department of Defense, or the U.S. government.

in reply: Thank you for bringing these articles to our attention. The decision tool may perform well when the typical and classic features of gout are present and may be especially valuable in resource-poor settings.12 However, its use is limited to straightforward cases. Synovial fluid testing remains indicated in patients with a mixed crystal arthritis, comprising both gout and pseudogout; when empiric gout treatment fails; or if there is a need for better informed decisions regarding newer generation uric acid–lowering agents, which are expensive and have considerable risks of other organ toxicity.34

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This series is coordinated by Kenny Lin, MD, MPH, deputy editor.

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