Background/Purpose:

Rheumatoid factor (RF) and anti-cyclic citrullinated peptide (CCP) positive rheumatoid arthritis (RA) patients develop more extra-articular disease manifestations and erosions, and have a worse prognosis than seronegative RA patients. Levels of RA and CCP may be regulated independently. Therefore, our aim was to identify demographic and clinical differences between RA patients grouped according to RF and CCP status.

Methods: Cross-sectional analysis of RA subjects from the Rheumatoid Arthritis Comparative Effectiveness Research (RACER) registry was performed. The analysis included data from the first visit at which  both RF and CCP levels were available (n=884). Patients were categorized based on clinical cut-offs: RF+CCP+, RF+CCP-, RF-CCP+, RF-CCP-. The following demographic and clinical data were compared across RF/CCP groups: age, race, gender, disease duration, CRP, RF, CCP , disease activity (DAS28, CDAI),rheumatoid nodules, morning stiffness, physician/patient global health assessment, and medication use (ever used DMARD, biologic, corticosteroid). Categorical and continuous variables were analyzed using chi-square and Kruskal-Wallis tests, respectively

Results:

60% of subjects were RF+CCP+, 12% RF+CCP-, 10% RF-CCP+ and 18% RF-CCP-. Disease duration, RF, CCP, CRP, DAS28 score, presence of rheumatoid nodules, morning stiffness, and use of biologic therapy were statistically significantly different across groups (p<0.05). RF+CCP+ patients had longer disease duration than other patients (median 143 vs 88-93 months), and higher median RF (122 vs 20-28) and CCP (118 vs 2-47). Mean CRP ranged from 2.8 (RF+CCP+) to 8.1 (RF-CCP-). Morning stiffness was most common in the RF-CCP- group (54% vs 26-40%), while rheumatoid nodules were more common in the CCP+ groups (12-15% CCP+ vs 5-6% CCP-). The proportion of patients ever having used biologic therapy ranged from 28% (RF+CCP-) to 56% (RF-CCP+). There were no statistically significant differences for the remaining demographic and clinical characteristics.

Conclusion:

There were statistically significant demographic, clinical and laboratory differences between RA subjects grouped on the basis of RF and CCP positivity.  RF+/CCP+ subjects had longer disease duration but were similar in age to the other groups, suggesting that earlier age of RA onset may be associated with the development of high levels of both RF and anti-CCP.  The associations of disease activity measures with RF levels (and not with CCP), suggests that RF levels vary with the degree of inflammation and disease activity (as does CRP) and are likely regulated by different factors than those that govern CCP levels.  The greater use of biologic therapies by CCP+ subjects suggests that these RA patients may experience greater disease severity.  An understanding of the differences between RA subjects grouped on the basis of RF and CCP status may allow for individualized treatment and will form the basis for future studies of the mechanisms differentially regulating RF and CCP levels.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/rheumatoid-arthritis-ra-patients-discordant-for-rheumatoid-factor-and-anti-ccp-positivity-have-different-clinical-and-laboratory-features-than-ra-patients-seropositive-or-seronegative-for-both-marke/