Background/Purpose: Consanguineous relatives of patients with RA are at a higher risk to develop RA. It is also known that specific antibodies including CCP and RF may occur years prior to the disease onset. To assess the predictive value of serum IgM-RF and anti-CCP to the development of RA in a 5-year prospective cohort of healthy consanguineous relatives of RA patients.

Methods: RA patients (ACR criteria) attending one tertiary- and two secondary-care outpatient rheumatology clinics were asked to invite their consanguineous relatives to participate in the study. All patients and relatives underwent medical history; serum IgM-RF (nephelometry) and anti-CCP antibodies (ELISA II) were determined in patients and healthy relatives at baseline. Thereafter participant relatives were contacted by phone every four months using a structured interview (COPCORD questionnaire). When COPCORD was positive subjects had an in-office rheumatology assessment including physical examination, erythrocyte sedimentation rate, and plain x-Ray. The outcome was defined as fulfillment of ACR-EULAR criteria of RA. The Kaplan Meier curve was done to assess the time to the outcome and Cox analysis was used to determine baseline predictors (age, sex, anti-CCP, IgM-RF).

Results: A total of 771 consanguineous relatives from 257 RA patients were included. At baseline, all had COPCORD negative and the mean age was 35 (±12), 69% were females and 33% siblings. Thirteen (2%) subjects were positive to both CCP and RF: 9 (1 %) only to CCP and 16 (2 %) only to RF. Sixteen of 771 subjects (2%) developed rheumatoid arthritis during the 5-yrs follow up (3348 person-years), with an annual rate of 0.5% (Kaplan-Meier). The positive predictive value when CCP and RF are positive was 54% and 56% when only CCP was positive. RF per se had no predictive value (table 1). Cox analysis showed that age at baseline, CCP, RF, and siblings were significant predictors for developing RA over follow-up.

Conclusion: The positivity of CCP may be useful to detect preclinical disease in healthy relatives of RA patients.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/predictive-value-of-anti-cyclic-citrullinated-peptide-and-rheumatoid-factor-to-the-development-of-rheumatoid-arthritis-in-a-cohort-of-healthy-relatives-of-patients-with-rheumatoid-arthritis/