Inclusion Criteria

• Patients with rheumatoid arthritis must meet both of the following criteria:
  • Fulfillment of the 2010 ACR/EULAR classification criteria for rheumatoid arthritis
  • Adult patients ≥ 18 years of age
• First-degree relatives and non-RA control subjects will be included if they meet both of the following criteria:
  • Adult subjects ≥ 18 years of age
  • No history of inflammatory arthritis, either by review of medical records or by self-reports.

Exclusion Criteria 

• History of inflammatory bowel disease
• History of celiac disease or malabsorption
• History of esophageal, gastric, or intestinal malignancy
• History of diarrhea or constipation within the past 2 weeks
• History of Clostridium difficile colitis
• History of pelvic irradiation
• Any antibiotic use within the past 2 weeks
• Patients who have had colonoscopy or other lower endoscopic procedure within the previous 2 weeks.
  • However if the patient otherwise meets eligibility criteria, they may submit the stool sample at a later date after a period of two weeks has elapsed.
  • The blood sample can be done at any time after consent as it is not affected by these procedures.