RA vs OA

Overview

Epidemiology and risk factors

Epidemiology

• Peak onset = 35-55 years, although occurs in all age groups
• Female:Male ratio = 3:1
• prevalence = 1%

Notable risk factors

• Smoking
  • The strongest modifiable risk factor
  • Dose-dependent and synergistic with HLA-DRB1
• HLA-DRB1
  • 'Shared epitope' alleles (DRB104:01 and DRB104:04 hence the association with DR4)
  • Encode a common amino-acid sequence that promotes presentation of citrullinated self-antigens to T cells
  • Strongly associated with seropositive rheumatoid arthritis (rheumatoid factor and anti-CCP positive)
• Periodontal disease
  • Especially Porphyromonas gingivalis
  • Can induce protein citrullination

Clinical Features

Respiratory Manifestations

A variety of respiratory problems may be seen in patients with rheumatoid arthritis:

• pulmonary fibrosis
• pleural effusion
• pulmonary nodules
• bronchiolitis obliterans
  • progressive dyspnoea
  • obstructive pattern on spirometry
  • centrilobular nodules, bronchial wall thickening is seen on CT
• complications of drug therapy e.g. methotrexate pneumonitis
• pleurisy