From the Guidelines
Rheumatoid arthritis (RA) and gout can be differentiated based on their distinct clinical features, with RA typically presenting with symmetric joint involvement and morning stiffness, while gout presents with sudden-onset, extremely painful monoarticular arthritis, often affecting the first metatarsophalangeal joint. The clinical features of RA and gout can be summarized as follows:
- RA:
- Symmetric joint involvement, particularly affecting small joints of hands and feet
- Morning stiffness lasting more than 30 minutes
- Persistent joint pain with gradual onset over weeks to months
- Swelling of metacarpophalangeal joints, proximal interphalangeal joints, and wrists
- Systemic manifestations like fatigue, low-grade fever, and weight loss
- Extra-articular features like rheumatoid nodules, interstitial lung disease, and ocular manifestations
- Gout:
- Sudden-onset, extremely painful monoarticular arthritis, often affecting the first metatarsophalangeal joint (podagra)
- Erythema and warmth suggesting infection
- Episodic attacks with complete resolution between attacks in early disease
- Presence of tophi (urate crystal deposits) in advanced gout
- Elevated serum uric acid levels and definitive presence of monosodium urate crystals in synovial fluid According to the most recent and highest quality study, the 2018 updated European League Against Rheumatism evidence-based recommendations for the diagnosis of gout 1, the diagnosis of gout should be based on the presence of monosodium urate crystals in synovial fluid or tophus aspirates, and clinical features such as monoarticular involvement of a foot or ankle joint, previous similar acute arthritis episodes, rapid onset of severe pain and swelling, erythema, and male gender. In terms of laboratory findings, RA often shows positive rheumatoid factor and anti-CCP antibodies, while gout shows elevated serum uric acid levels and the definitive presence of monosodium urate crystals in synovial fluid 1. It is essential to note that the diagnosis of gout should not be made on the presence of hyperuricaemia alone, and that synovial fluid aspiration and examination for crystals should be undertaken in any patient with undiagnosed inflammatory arthritis 1. Overall, the clinical features and laboratory findings of RA and gout can help differentiate between these two conditions, and the diagnosis of gout should be based on a combination of clinical features, laboratory findings, and imaging studies, with the presence of monosodium urate crystals in synovial fluid or tophus aspirates being the gold standard for diagnosis 1.
From the Research
Clinical Features of Rheumatoid Arthritis
The clinical features suggestive of rheumatoid arthritis (RA) over gout include:
- Symmetrical small joint polyarthritis, which is a characteristic feature of RA 2
- Morning stiffness, which is a common symptom of RA 2
- Constitutional symptoms, such as fatigue and fever, which can occur in RA 2
- Extra-articular manifestations, such as lung, skin, and eye involvement, which can be seen in RA 3, 2
- Elevated inflammatory markers, such as C-reactive protein, rheumatoid factor, and anti-cyclic citrullinated peptide antibody, which are commonly found in RA 3, 2
Comparison with Gout
In contrast, gout is characterized by:
- Swelling, pain, or tenderness in a peripheral joint or bursa, often with the development of a tophus 4
- Acute episodes of pain, which can be relieved with colchicine, nonsteroidal anti-inflammatory drugs, and corticosteroids 4
- Risk factors, such as male sex, obesity, hypertension, and diet, which are different from those associated with RA 4
Diagnostic Considerations
A diagnosis of RA should be considered if there is at least one joint with definite swelling that is not better explained by another disease, and if the patient has a rheumatoid factor and/or anti-citrullinated protein antibody, elevated C-reactive protein level, or elevated erythrocyte sedimentation rate 3. In contrast, a diagnosis of gout can be made using several validated clinical prediction rules, and arthrocentesis should be performed when suspicion for an underlying septic joint is present 4.