Anti-cyclic citrullinated peptide (CCP) antibody is an important biomarker as-sociated with the diagnosis and prognosis of rheumatoid arthritis (RA). Different studies showed inconsistency in the relationship between anti-CCP antibody titers and RA disease activity. Therefore, we investigated the association between anti-CCP antibody with the possibility of achieving treatment target and flare.

The enrolled RA patients must be anti-CCP antibody positive at baseline, and had at least one test result of anti-CCP antibody during follow-up at least one year after the baseline. The patients were divided into declined group and non-declined group according to the decrease of anti-CCP antibody titer over 10% or not during follow-up from the baseline. Single factor comparison, Pearson correlation, Spearman correlation and Kendall correlation analysis were used.

A total of 124 patients were included in this study. Sixty-five and 59 patients were in anti-CCP antibody declined and non-declined groups, respectively. At the end of the follow-up, the proportion of patients who achieved clinical remission or low disease activity were 78%(51/65) and 68% (40/59)in the declined and the non-declined groups, respectively (P=0.181). The changes of Disease Activity Score with 28 joint (DAS28)-C-reaction protein (CRP), DAS28-erythrocyte sedimentation rate (ESR), tender joint count (TJC) and CRP in the declined group were significantly greater than those of the non-declined group (P values <0.05). There was no positive correlation between anti-CCP antibody titer and several disease activity indicators at baseline ( r values <0.3, P values >0.05). The changes of anti-CCP antibody titers during the follow-up were also not correlated with changes in disease activity (but r values <0.3, P values <0.05). Meanwhile, both the baseline anti-CCP antibody titers and the changes of the anti-CCP antibody titers during follow-up were neither correlated with whether the patient achieved clinical remission or low disease activity at the end of the follow-up nor whether relapse happened.

There is no significant correlation between anti-CCP antibody levels at baseline and disease activity, achievement of treatment target, or recurrence after treatment. The value of anti-CCP antibody in assessing disease activity, predicting treatment response, and predicting relapse needs to be confirmed in further large-scale prospective studies.

Arthritis, rheumatoid; Anti-cyclic citrullinated peptide antibody; Disease activity; Clinical target; Recurrence