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EULAR: Gout diagnosis should not depend on hyperuricemia alone
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Physicians should refrain from diagnosing gout based solely on hyperuricemia, according to updated EULAR recommendations published in the Annals of the Rheumatic Diseases.
“Despite effective treatments, gout is still often misdiagnosed and its management remains suboptimal,” Pascal Richette, MD, PhD, AP-HP, of Hopital Lariboisiere Centre Viggo Petersen in Paris, and colleagues wrote. “This may explain why the premature mortality among patients with gout remains unimproved over the last decade.”
“In 2006, the EULAR produced its first evidence-based recommendations for the diagnosis of gout,” they added. “The 2006 task force agreed that detection of [monosodium urate (MSU)] crystals in synovial fluid (SF) was the gold standard for the diagnosis of gout. Since then, a number of studies have explored the diagnostic value of clinical algorithms and of imaging modalities such as ultrasound (US) or dual-energy CT (DECT). This prompted a revision of the 2006 recommendations following an updated systematic literature review and a Delphi process to achieve consensus.”
To update the 2006 EULAR recommendations for gout diagnosis, Richette and colleagues formed a task force with participants from 12 European countries, including 15 rheumatologists, one musculoskeletal radiologist, two general practitioners, one research fellow, two patients and three experts in epidemiology and methodology. Members of the task force performed a systematic literature review of articles published since Jan. 1, 2005, up to July 2018, which uncovered 1,173 records, of which 83 were included in their analysis.
The task force used a Delphi consensus approach, in which members attended a 2-day meeting where the results of the literature review were presented and debated. The members then drafted a preliminary set of new recommendations. After four Delphi rounds, conducted through email, the task force reached a consensus on eight updated recommendations.
According to the task force, this update amends all previous EULAR recommendations for the diagnosis of gout. The final set of eight updated recommendations are:
- Physicians should search for crystals in synovial fluid or tophus aspirates in every patient with suspected gout, as monosodium urate crystals allow for a “definitive diagnosis of gout;”
- Physicians should consider gout in the diagnosis of any adult patient with acute arthritis. In addition, whenever synovial fluid analysis is not available, a diagnosis of gout can be made via monoarticular involvement of a foot or ankle joint, previous similar acute arthritis episodes, rapid onset of severe pain and swelling that is at its worst within the first 24 hours, erythema, male gender and associated cardiovascular diseases and hyperuricemia;
- Synovial fluid aspiration and evaluation for crystals should be performed in any patient with undiagnosed inflammatory arthritis.
- The diagnosis of gout should not be made based solely the presence of hyperuricemia;
- When the diagnosis is uncertain, and crystal identification is not possible, patients should be examined through imaging to search for monosodium urate crystal deposits and signs of any other diagnosis;
- Although plain radiographs are indicated to search for evidence of monosodium crystal deposits, they have limited value for diagnosing a gout flare. Ultrasound can be more helpful in diagnosing patients with suspected gout flare or chronic gouty arthritis;
- Physicians should search for risk factors for chronic hyperuricemia in every patient with gout, specifically chronic kidney disease, being overweight and consumption of excess alcohol, as well consuming nondiet sodas, meat and shellfish; and
- Physicians should perform systematic evaluations for associated comorbidities in patients with gout, including obesity, renal impairment, hypertension, ischemic heart disease, heart failure, diabetes and dyslipidemia.
“The task force recommends a three-step approach for the diagnosis of gout,” Richette and colleagues wrote. “The first step relies on MSU crystal identification when SF analysis is feasible. If not possible, the second step relies on a clinical diagnosis based on suggestive and associated clinical features of gout and presence of hyperuricemia. When a clinical diagnosis of gout is uncertain and crystal identification is not possible, the third step recommends imaging, particularly US, to search for imaging evidence of MSU crystal deposition.” – by Jason Laday
Disclosures: Richette reports honoraria from Astra-Zeneca, Grünenthal , Ipsen/Menarini and Savient. Please see the full study for additional authors’ disclosures.
Perspective
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Paul J. DeMarco, MD, FACP, FACR, RhMSUS
Richette and colleagues have undertaken the wonderful task of updating the EULAR evidence-based recommendations for the diagnosis of gout. Through a Dephi consensus approach, eight evidence-based recommendations are proposed.
The previous ten recommendations were retired in favor of these adapted eight recommendations:
- Synovial fluid or tophaceous deposition crystal analysis is recommended in suspected gout, as MSU identification is definitive for diagnosis of gout.
- Clinical diagnosis of gout is supported by suggestive features: monoarticular involvement of the foot or ankle, similar arthritic episodes, rapid onset of severe pain and swelling, joint erythema, male gender and associated CV diseases and hyperuricemia.
- Undiagnosed arthritis be assessed with synovial fluid analysis seeking crystals.
- Gout should not be diagnosed by hyperuricemia alone.
- Uncertain clinical diagnosis and absent crystal identification should prompt imaging evidence of MSU deposition.
- While plain radiographs are indicated to identify gouty arthritis, radiographs are limited in value whereas ultrasound scanning for a double contour or tophi is useful in identifying patients with gouty arthritis.
- Risk factors for gouty arthritis should be sought in gout patients, specifically chronic kidney disease, overweight status, medications and high-risk dietary behaviors (such as excessive alcohol and non-diet soda consumption, meat and shellfish consumption).
- Systematically assess for comorbidities, such as obesity, renal impairment, hypertension, ischemic heart disease, heart failure, diabetes and dyslipidemia.
The EULAR statement is practical and accessible, giving clinicians clear areas to focus for care and management. These are well-crafted, useful to review and important in a time when mortality from this common and identifiable arthropathy has not changed in a decade.
Perspective
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David A. McLain, MD, FACP, FACR
While the task force recommends the search for uric acid crystals “in every person with suspected gout,” they recognize that this may not be possible. First, the setting where the patient is seen – often in the ED, urgent care center or PCP office – may not have the person with the skill or facilities to obtain synovial fluid analysis. Second, is “the challenge of aspirating SF, without patient discomfort, from small joints or from certain anatomical regions such as the midfoot and wrist.”
This reminds me of when I was new in practice and a patient presented with acute podagra; I had my polarizing microscope and thought that aspirating this swollen, tender, painful first metatarsophalangeal would be a good idea to look for MSU crystals. Even with lidocaine anesthesia, which was itself painful for the patient to endure, the aspiration failed to return any fluid and the patient never returned. That was the last time I attempted to aspirate acute podagra.
The task force also reviewed the fact that hyperuricemia is not enough to diagnose gout. They referenced a 2018 study that found only 50% of patients with a SUA above 10 mg/dL developed gout over 15 years.
Dual-energy computed tomography (DECT) was also discussed as it was a new development in the diagnosis of gout since the 2006 EULAR recommendations. DECT scanning is not as sensitive in early disease as it is in tophaceous disease; moreover, the authors note that DECT is expensive, often located only in tertiary centers, and is restricted by third party payers. However, DECT has helped us understand intercritical gout and is more sensitive and specific than ultrasound.
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