Rheumatoid Arthritis

Question 1

What is rheumatoid arthritis?

Answer 1

• Autoimmune disease, symmetrical, small joint, inflammatory polyarthropathy.
• Typically presents in MCP joints, PIP joints, wrist, ankle, MTP joints, cervical spine and some large joints (hips, knees, shoulders).
• There is chronic inflammation of the synovial lining of the joints, tendon sheaths and bursa.
• Three times more common in women than men.

Question 2

What symptoms are seen in RA?

Answer 2

• Pain (improves with activity, worse after rest), swelling and stiffness
• Fatigue, weight loss, flu-like illness, muscle aches and weakness
• Ulnar deviation, muscle wasting and Z-thumb are common signs in the hands along with Boutonierre deformity (tear in central slip of extensor components - lateral tendons go around the PIP and pull on distal phalynx) and swan-beck deformity
• Outside the joint can cause bronchiolitis obliterans, Felty’s syndrome (RA, neutropenia, splenomegaly), Sjogren’s syndrome, anaemia of chronic disease, CV disease, myelopathy, scleritis, pulmonary fibrosis, serositis, nodules, amyloidosis, carpal tunnel syndrome, lymphoma and peripheral neuropathy
• Atlantoaxial subluxation can occur in the cervical spine leading to cord compression.

Question 3

How is RA diagnosed?

Answer 3

• ESR (plasma proteins reduce charge on RBCs causing them to fall faster)
• CRP (can be normal or active in RA)
• Rheumatoid factor (IgM directed against Fc component of other antibodies (IgG), positive in 70% of RA)
• Anti-CCP antibodies (98% specific for RA)
• Refer urgently if involvement of small joints of hands or feet even if negative blood tests

Question 4

How is RA treated?

Answer 4

• NSAIDs/COX-2 inhibitors are effective but risk of GI bleeding
• Short course of steroids can help to settle disease at first
• First line is monotherapy with methotrexate, leflunomide or sulfasalazine
• Hydroxychloroquine can be considered in mild disease
• Second line is a combination of the two
• Third line is methotrexate plus biologic therapy, usually a TNF inhibitor
• Fourth line is methotrexate plus rituximab

Question 5

Genetic associations

Answer 5

• HLA DR4 (often present)
• HLA DR1 (occasionally present)

Question 6

X-ray changes in RA

Answer 6

• Joint destruction and deformity
• Soft tissue swelling
• Periarticular osteopenia
• Boney erosions

Question 7

Scoring systems

Answer 7

• European league against rheumatism (ELAR) for diagnosis scored on:
  
  • Joints involved (more and smaller score higher)
  • Serology (rheumatoid factor and anti-CCP)
  • Inflammatory markers (ESR and CRP)
  • Duration of symptoms (more or less than 6 weeks)
• DAS28 Score for disease activity scored on:
  
  • Swollen joints
  • Tender joints
  • ESR/CRP results

Question 8

Prognosis of RA

Answer 8

• Worse if:
  
  • Younger onset
  • Male
  • More joints and organs affected
  • Presence of RF and anti-CCP
  • Erosions seen on X-ray

Question 9

Notable side effects of RA drugs

Answer 9

• Methotrexate (pulmonary fibrosis)
• Leflunomide (HTN, peripheral neuropathy)
• Sulfasalazine (male infertility)
• Hydroxychloroquine (nightmares, reduced visual acuity)
• Anti-TNF (reactivation of TB or hepatitis B)
• Rituximab (night sweats, thrombocytopenia)

Question 10

Mechanism of action of common RA drugs

Answer 10

• Methotrexate - interferes with metabolism of folate suppressing certain components of the immune system
• Leflunomide interferes with production of purimidine (component of RNA and DNA)
• Sulfasalazine - immunosuppressant, may interfere with folate metabolism
• Hydroycholoroquine - interferes with Toll-like receptors affecting antigen presentation
• Infliximab, enteracept, adalimumab - anti-TNF
• Rituximab - anti-CD20