Impact of Dual Rheumatoid Factor and Anticitrullinated Protein Antibody Seropositive, Single Seropositive, and Seronegative Rheumatoid Arthritis on Outcomes.

OBJECTIVE

The objective of this study was to investigate the association between dual seropositive, single seropositive, and seronegative rheumatoid arthritis (RA) with radiographic erosions, disease flares, and death.

METHODS

We performed a retrospective, population-based study of residents in Southern Minnesota with incident RA who fulfilled criteria for RA in 2003 to 2019. Radiographic erosions and flares were evaluated within one year of incident RA. All-cause mortality was obtained from medical records and death certificates. Cox models adjusted for age, sex, smoking status, year of incident RA, and comorbidities were used.

RESULTS

The study included 1,373 patients with RA. At RA incidence, 37% were dual seropositive, 13% seropositive for anti-cyclic citrullinated protein (anti-CCP) only, 12% seropositive for rheumatoid factor (RF) only, and 38% seronegative. The highest proportion of radiographic erosions before or within one year of RA incidence was in the dual seropositive (31%) and lowest in those seropositive for anti-CCP only (13%). Flares occurred in 69% of the dual seropositive and 51% of the seropositive for anti-CCP only within the first year of RA incidence. Those seropositive for RF only had over a two-fold increase in mortality rates compared with the seronegatives (adjusted hazard ratio [aHR] 2.18, 95% confidence interval [CI] 1.47-3.24). In contrast, the dual seropositives had only a >50% increase in mortality rates (aHR 1.66, 95% CI 1.21-2.28), and those seropositive only for anti-CCP had a >30% increase in mortality rates (aHR 1.32, 95% CI 0.83-2.11).

CONCLUSION

Patients with RA seropositive for RF only have an increase in mortality rates compared with patients who are dual seronegative. RF positivity could be an indicator of inflammation that requires pharmacologic treatment to decrease mortality rates.