RA Factor, FR, Rheumatoid Arthritis
Diagnosis and prognosis of rheumatoid arthritis
See the Mixed Connective Tissue Disease Panel Algorithm for suggested testing strategy.
Rheumatoid arthritis (RA) is an autoimmune disease characterized by chronic inflammation. The presence of autoantibodies, such as rheumatoid factor (RF) and anti-citrullinated protein antibody (ACPA; tested as anti-cyclic citrullinated peptide [anti-CCP]) can precede clinical manifestation of RA by many years. The 2010 ACR rheumatoid arthritis classification criteria focus on the need for earlier diagnosis and institution of effective disease-suppressing therapy to prevent individuals from reaching the chronic, erosive disease state exemplified in the 1987 RA criteria. It defines “definite RA” as a total score of 6 or greater (of a possible 10) from the individual scores in 4 domains:
Number and site of involve joints (score range 0 – 5)Serologic abnormality (score range 0 – 3)Elevated acute-phase response (score range 0 – 1)Symptom duration (2 levels; range score 0 – 1)
Negative: < = 13 IU/mL score = 0Low Pos: > 13 to 39 IU/mL, score = 2High Pos: > 40 IU/mL, score = 3