Background/Purpose: A number of studies have investigated the association between serum RF and joint damage in early and established RA patients, and positive and high-titer RF has been a risk or predictive factor of joint damage in RA patients. However, it still remains unclear whether the changes in serum RF titers were correlated with progressions of joint damage in RA. The purpose of this study is to clarify whether continuous decrease in RF titer during anti-TNF therapy was associated with suppression in progression of RA joint damage.

Methods: The subjects were 55 RA patients who filled RA criteria 2010, were treated with adalimumab, certolizumab pegol or golimumab, had serum RF titer ≥45 IU/ml at entry (at starting anti-TNF therapy, month 0), and were followed up until month 12. Their medical records were reviewed retrospectively. Serum RF titers were measured at the entry, month 4 and 12 months after starting TNF inihibitor. More than 10% reduction in RF titer was considered as significant decrease, and continuous decrease in RF titer was defined as significant reductions during both month 0-4 and 4-12. RA disease activity and radiographic progression were assessed by DAS28-CRP and modified total Sharp score (mTSS) at month 0 and 12. In case of withdrawal from anti-TNF therapy during month 4-12 due to some causes, data upon the discontinuation of TNF inhibitor was used as that at month 12 using the last observation carried forward method.

Results: Subjects were 9 male and 46 female, were median age 54.8 years with 3.5 years of disease duration, and were treated with 8 mg/week of median MTX dosage. Median DAS28-CRP and mTSS were 3.23 (interquartile range [IQR] 2.15–4.46) and 6 (IQR 1-20), respectively. After starting TNF inhibitor, the serum RF titer decreased from 104 IU/ml (median) at month 0 to 72 at month 4 (p< 0.0001) and 52 at month 12 (p=0.0122). Although median DAS28-CRP decreased from 3.23 at month 0 to 1.81 at month 12 (p< 0.0001), mTSS increased from 6 (IQR 1-20) to 6 (IQR 2-22) (p< 0.0001) and the radiographic progression (yearly change in mTSS >0.5) was found in 43.6%. During anti-TNF therapy, 26 of 55 subjects showed continuous decrease (CD) in serum RF titer, and 29 cases did not (non-CD). Between these groups, there were no differences in baseline characteristics at the entry, and DAS28-CRP at month 0, 4 and 12. The median changes in mTSS during month 0-12 were 0 in CD patients and 1.09 in non-CD, and the yearly radiographic change in mTSS was greater in non-CD group (p=0.0015). The radiographic remission (yearly change in mTSS ≤0.5) was found in 71.4% of CD patients and 13.3% of non-CD, and ratio of radiographic remission was higher in CD group (p=0.0036). The yearly progression in bone erosion score during month 0-12 was greater in RA patient with non-CD than with CD (p=0.0037), but no significant difference between CD and non-CD was observed in the joint space narrowing score. Multiple regression analysis revealed that the continuous RF decrease as well as RA disease activity was significantly correlated with yearly change in bone erosion score during month 0-12.

Conclusion: Continuous decrease in serum RF titer was associated with less progression in mTTS, especially in bone erosion score, of RA patients treated with TNF inhibitors.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/continuous-decrease-in-serum-rf-titer-during-anti-tnf-therapy-was-associated-with-suppression-in-progression-of-ra-joint-damage/