Gout Management

Introduction

• Gout is a common rheumatic disease of adulthood, with a self-reported prevalence in the USA estimated at 3.9% of adults (approximately 8.3 million people), and more recent data suggesting a prevalence of 5.1% (affecting 12.1 million adults) 1

Diagnosis and Indications for Treatment

• Definitive diagnosis requires identification of monosodium urate (MSU) crystals in synovial fluid or tophus aspirates, and chronic gout has distinctive clinical features, including history of prior acute gout attacks, presence of visible tophi, characteristic radiographic changes, and persistent hyperuricemia 2
• Asymmetrical joint swelling has a likelihood ratio (LR) of 4.13 for chronic gout diagnosis, and subcortical cysts without erosion on radiography have an LR of 6.39 3
• Serum uric acid (SUA) levels do not confirm or exclude gout, as many people with hyperuricemia never develop gout, and levels may be normal in up to 14-63% of patients during acute attacks 3, 2
• A cut-off level of 6 mg/dl (360 μmol/L) has moderate sensitivity (0.67) and specificity (0.78) for diagnosing gout, while a higher cut-off of 7 mg/dl (420 μmol/L) has reduced sensitivity (0.57) but increased specificity (0.92) 3
• The presence of tophi is a clear indication for initiating urate-lowering therapy (ULT), according to rheumatology guidelines, as it indicates chronic hyperuricemia and substantial urate crystal burden 1
• The American College of Rheumatology recommends ULT for patients with tophi, as it is a marker of disease burden and risk of complications, with a strength of evidence considered high 4

Diagnostic Imaging and Testing

• Joint aspiration is recommended when possible to confirm diagnosis, and imaging modalities like ultrasound can detect both MSU crystal deposition and synovitis, with a sensitivity of 63-83% and specificity of 76-92% 5, 6
• Dual-Energy CT (DECT) is excellent for detecting MSU crystal deposits, with a sensitivity of 85-100% and specificity of 83-92% 6
• Ultrasound is the first-line imaging option, showing double contour sign at cartilage surfaces or detection of tophi not evident on clinical examination, with a sensitivity of 63-83% and specificity of 76-92% 2
• The following table summarizes the diagnostic accuracy of different imaging modalities:

Treatment Approaches

• Proper management of chronic gout requires urate-lowering therapy with a target serum urate level of <6 mg/dL as a minimum, or <5 mg/dL for faster tophi resolution, and early diagnosis and treatment are essential to prevent the progression to chronic tophaceous gout and its associated complications 2
• First-line ULT options include allopurinol, febuxostat, probenecid, and benzbromarone, with combination therapy (XOI + uricosuric agent) or pegloticase used for refractory cases 1, 7
• The target serum urate level for ULT is <6 mg/dL (minimum) or <5 mg/dL for faster tophi resolution, with first-line options including allopurinol, febuxostat, and probenecid or benzbromarone (uricosuric agents) 1
• Combination therapy (XOI + uricosuric agent) or pegloticase may be considered for refractory cases of severe tophaceous gout unresponsive to conventional therapy, with a strength of evidence considered moderate 4

Monitoring and Prophylaxis

• Regular measurement of serum urate levels, clinical assessment of tophi size and number, and ultrasound or DECT can be used to monitor tophi regression, with prophylaxis against acute flares provided when initiating ULT to prevent increased risk of flares 2, 1
• Prophylaxis against acute flares is recommended when initiating ULT, with a strength of evidence considered moderate 4
• Regular monitoring of serum urate levels, clinical assessment of tophi size and number, and ultrasound or DECT to monitor tophi regression is recommended, with a strength of evidence considered high 1

Comorbidities and Risk Factors

• Risk factors for gout and associated comorbidities should be assessed, including features of metabolic syndrome (obesity, hyperglycemia, hyperlipidemia, hypertension), with comorbidities such as obesity, renal impairment, hypertension, ischemic heart disease, heart failure, diabetes, and dyslipidemia considered to avoid misdiagnosis and inadequate management 2, 3
• Gout and sepsis may coexist, so when septic arthritis is suspected, Gram stain and culture of synovial fluid should still be performed even if MSU crystals are identified, with full investigation for sepsis undertaken to prevent joint destruction and systemic complications 3, 2