What are the key clinical features and laboratory tests that support the diagnosis of rheumatoid arthritis in primary care?

Key clinical features supporting the diagnosis of rheumatoid arthritis (RA) in primary care include:

• Persistent synovitis, especially affecting the small joints of the hands or feet.
• Involvement of more than one joint.
• Symptoms persisting for 3 months or longer before seeking medical advice.
• Signs such as joint swelling, tenderness, stiffness (particularly morning stiffness lasting more than 30 minutes), and loss of joint function.
• Exclusion of other causes such as septic arthritis, especially if a single joint is hot and swollen.

Laboratory tests that support diagnosis include:

• Rheumatoid factor (RF) blood test offered to adults with suspected RA who have synovitis on clinical examination.
• If RF is negative but suspicion remains, measurement of anti-cyclic citrullinated peptide (anti-CCP) antibodies is recommended.
• Inflammatory markers such as C-reactive protein (CRP) and erythrocyte sedimentation rate (ESR) may be elevated but normal results do not exclude RA.
• X-rays of the hands and feet to detect erosions or joint damage, although these may be normal early in the disease.

Referral to rheumatology for specialist assessment should not be delayed by awaiting blood test results, especially if clinical features strongly suggest RA.

Early diagnosis and referral are critical to initiate treatment within 3 months of symptom onset to improve outcomes.

This integrated approach aligns with NICE guidelines emphasizing clinical diagnosis supported by RF and anti-CCP testing, inflammatory markers, and imaging, combined with prompt referral for persistent synovitis affecting small joints or multiple joints ¹. Early primary care recognition and investigation are also supported by literature highlighting the importance of early diagnosis and treatment to prevent joint damage and disability (Calabrese, 1999).