What are the diagnostic criteria for gout (gouty arthritis)?

From the Guidelines

Gout is best diagnosed through a combination of clinical evaluation, laboratory tests, and imaging studies, with the most definitive method being joint fluid analysis to identify characteristic monosodium urate crystals. The diagnosis of gout should follow a three-step approach: first, searching for MSU crystals in synovial fluid or tophus aspirates; second, making a clinical diagnosis based on the presence of hyperuricaemia and associated clinical features of gout if crystal identification is not feasible; and third, using imaging studies, particularly ultrasound or dual-energy CT, to search for evidence of MSU crystal deposition when a clinical diagnosis is uncertain and crystal identification is not possible 1.

Key Diagnostic Considerations

• Joint fluid analysis is the gold standard for diagnosing gout, with a high sensitivity and specificity for identifying MSU crystals 1.
• Clinical presentation, including sudden onset of severe joint pain, swelling, redness, and warmth, is crucial for diagnosis, especially in patients with typical symptoms such as podagra (inflammation of the first metatarsophalangeal joint) 1.
• Blood tests, including serum uric acid levels, are important but not definitive on their own, as elevated levels can be present in people without gout and normal levels can be seen in patients with gout during an acute attack 1.
• Imaging studies like X-rays, ultrasound, and dual-energy CT scans can provide additional evidence for gout, particularly in chronic cases or when joint fluid analysis is not possible 1.

Diagnostic Algorithms and Imaging

• Clinical diagnostic algorithms, such as those proposed by the American College of Physicians, can help guide the diagnosis of gout based on clinical signs and symptoms, but their specificity may not be high enough to replace MSU crystal identification 1.
• Ultrasonography and dual-energy CT scans have shown promise in diagnosing gout, especially in detecting crystal deposits and the "double contour" sign characteristic of gout, but their accessibility and utility in primary care settings may be limited 1.

Conclusion and Recommendation

Given the evidence, the most accurate diagnosis of gout is achieved through a combination of clinical evaluation and joint fluid analysis, with imaging studies and laboratory tests providing supportive evidence. Clinicians should prioritize joint fluid analysis for definitive diagnosis, especially in cases where the diagnosis is uncertain or when differentiating gout from other forms of arthritis is necessary 1.

From the FDA Drug Label

The evidence for the efficacy of colchicine in patients with chronic gout is derived from the published literature. Patients meeting American College of Rheumatology criteria for gout were randomly assigned to three groups

The diagnosis of gout is based on the American College of Rheumatology criteria.

• The FDA drug label does not provide direct information on how to diagnose gout, but it mentions that patients in the study met these criteria.
• No conclusion can be drawn on the specific diagnostic methods for gout from this label 2.

From the Research

Diagnosis of Gout

• Gout is a common form of acute inflammatory arthritis caused by the deposition of monosodium urate crystals within the synovium of joints, leading to severe pain and reduced quality of life for patients 3.
• The diagnosis of gout is typically characterized by painful joint inflammation, most commonly in the first metatarsophalangeal joint, resulting from precipitation of monosodium urate crystals in a joint space 4.
• Demonstrating the presence of monosodium urate (MSU) crystals in the joint fluid or tophus has been the gold standard for the diagnosis of gout 5, 6.

Clinical Presentation

• Acute gouty arthritis typically presents with a sudden and severe exquisitely painful joint, most classically in the first metatarsophalangeal joint (toe) 5.
• Acute gouty arthritis typically presents with rapid development of severe joint pain, swelling, and tenderness that reaches its maximum within just 6-12 h, especially with overlying erythema 6.

Laboratory and Radiologic Findings

• In the absence of demonstrating the presence of MSU crystals in aspirated joint fluid or tophus, clinical, radiologic, and laboratory criteria are helpful in diagnosing gout 5, 6.
• Diagnosis may be confirmed by identification of monosodium urate crystals in synovial fluid of the affected joint 4.

Classification Criteria

• Gout is typically diagnosed using clinical criteria from the American College of Rheumatology 4.
• This article presents an overview of the various classification criteria, clinical presentations, and laboratory and radiologic studies needed to make the diagnosis of gout 5, 6.