How accurate are rheumatoid factors (RFs) assays?

Updated: Jan 28, 2021
  • Author: Tyler Street, MD; Chief Editor: Eric B Staros, MD  more...
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False-negative and false-positive results are common in patients without RA, as well as those with RA; patients without RA have an 8% rate of false results, whereas patients with RA have a 15% rate.

RF results may be positive in patients without RA who have the following conditions:

Systemic lupus erythematosus




Viral hepatitis

Infectious mononucleosis


Because of its poor specificity and poor positive predictive value, RF is only one test used to diagnose RA and must be ordered judiciously and with purpose. [4]

See Rheumatoid Arthritis: In and Out of the Joint, a Critical Images slideshow, to help identify the distinguishing features of RA as well as the signs of extra-articular manifestations of this disfiguring disease.

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