Description

• Rheumatoid arthritis (RA) is a chronic inflammatory disease primarily causing synovial inflammation and leading to the destruction of bone and cartilage (1).
• Classification: based on the duration of disease (1)
  • Early: ≤6 months
  • Established: ≥6 months
  • Based on the disease activity: low, moderate, high, or remission

Epidemiology

Incidence
Annual incidence: the United States is approximately 40 per 100,000 persons.

Prevalence

• Prevalence: 0.2–1% of the general population worldwide
• Female:male, 2:1
• Males more likely to develop extra-articular RA

Etiology and Pathophysiology

The cause remains uncertain; often precipitated by stress or insult (e.g., infection, smoking, trauma, inhalants, mucosal dysbiosis, chronic lung diseases)

Genetics
Estimated heritability 40%, >100 risk loci, HLA-DRB1 (the strongest genetic predisposition)

Risk Factors

Females at a younger age (5th to 6th decade), first- and second-degree relative, North American regions, Native Americans, smoking, obesity, lower socioeconomic status, infections