Background/Purpose: First-degree relatives (FDRs) of patients with rheumatoid arthritis (RA) are at increased risk for developing RA compared to the general population. The purpose of the study reported herein was to evaluate the incidence rate of RA from a local cohort of FDRs that was initiated in 2004.

Methods: FDRs of patients with RA from Cedars-Sinai Medical Center (CSMC) enrolled in the Studies of the Etiology of RA (SERA, a multicenter prospective cohort of FDRs of probands with RA) were studied (Kolfenbach 2009). Participants were enrolled between 2004 and 2011, providing an average of 9.5 years of follow-up. FDRs who live in Southern California within approximately 150 miles of CSMC were contacted by phone and asked if they were given a diagnosis of RA by a rheumatologist or if they reported pain in one or more joints, and/or swelling or morning stiffness. If they had symptoms, but were not yet diagnosed with RA, they were evaluated in clinic by a rheumatologist and underwent testing for CCP antibodies (CCP 3.1).

Results: 250 FDRs enrolled in SERA between 2004 and 2011 and seen at CSMC who live in Southern California were contacted by telephone. 73 out of 250 subjects (29.2%) were reached to date. 2/73 FDRs (3%) reported a diagnosis of RA by a rheumatologist. Both FDRs diagnosed with RA were seronegative at the time of enrollment in the SERA cohort. One who was initially seronegative in 2007 seroconverted in 2011, with CCP2 and RF IgG positivity – she was diagnosed with RA in 2014. The second FDR diagnosed with RA remained seronegative for the duration of follow-up, even post-diagnosis. 9 of 73 FDRs (12.3%) had arthralgias defined as pain in one or more joints. Of these, 4 of the 9 have been evaluated to date by a rheumatologist in clinic without evidence of RA; none were CCP positive.

Conclusion: Our local cohort follow-up suggests that FDRs of patients with RA develop RA at a higher rate than the general population with an incidence rate of 3% in FDRs versus 0.4% in the general population over 10 years¹. This is an ongoing effort to prospectively evaluate the risk of development of RA from a subgroup of FDRs established in the United States (SERA).

References:

1. Myasoedova, Elena, et al. “Is the incidence of rheumatoid arthritis rising?: results from Olmsted County, Minnesota, 1955–2007.” Arthritis & Rheumatology 62.6 (2010): 1576-1582.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/incidence-of-rheumatoid-arthritis-in-a-cohort-of-first-degree-relatives-from-the-studies-of-the-etiology-of-rheumatoid-arthritis/