Objective To examine associations of anti-cyclic citrullinated peptide (aCCP) antibody and rheumatoid factor (RF) concentrations with future disease activity in men with rheumatoid arthritis (RA).
Methods Outcome measures were examined in male US veterans with RA and included (1) proportion of observations in remission (disease activity score (DAS28) ≤2.6); (2) remission for ≥3 consecutive months; and (3) area under the curve (AUC) for DAS28. The associations of autoantibody concentration (per 100 unit increments) with outcomes were examined using multivariate regression.
Results 826 men with RA were included in the analysis; the mean (SD) age was 65 (10.5) years and follow-up was for 2.6 (1.3) years. Most were aCCP (75%) and RF (80%) positive. After multivariate adjustment, aCCP (OR 0.93; 95% CI 0.89 to 0.96) and RF concentrations (OR 0.92; 95% CI 0.90 to 0.94) were associated with a lower odds of remission, a lower proportion of observation in remission (p=0.017 and p=0.002, respectively) and greater AUC DAS28 (p=0.092 and p=0.007, respectively). Among patients with discordant autoantibody status, higher concentrations of both aCCP and RF trended towards an inverse association with remission (OR 0.93; 95% CI 0.83 to 1.05 and OR 0.80; 95% CI 0.59 to 1.10, respectively).
Conclusions Higher aCCP concentrations (particularly in RF-positive patients) are associated with increased disease activity in US veterans with RA, indicating that aCCP concentration is predictive of future disease outcomes in men.
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Funding BJM was supported by the Ephraim P Engleman Endowed Resident Reseach Preceptorship from the American College of Rheumatology (ACR) Research and Education Foundation. This work was funded by a grant from NIH/NIAMS (R03 AR054539, PI TRM). The VARA Registry has received research support from the Health Services Research & Development (HSR&D) Program of the Veterans Health Administration (VHA) in addition to unrestricted research funds from Abbott Laboratories and Bristol-Myers Squibb. TRM receives research support from NIAMS (K23 AR050004) and the VHA (VA Merit). LC is supported by a VA HSR&D Career Development Award.
Competing interests None.
Ethics approval This study was conducted with the approval of the IRB from all the enrolling sites (VA Medical Centers in Dallas, Texas; Denver, Colorado; Jackson, Mississippi; Omaha, Nebraska; Portland, Oregon; Salt Lake City, Utah; and Washington, DC) and patients provided informed written consent prior to enrolment.
Provenance and peer review Not commissioned; externally peer reviewed.