PRTN3 and rheumatoid arthritis: Patients were categorized into three groups according to ACPA titers: ACPA + high titer group, ACPA + low titer group, and ACPA-negative.Except for RF, which showed a significant difference (P < 0.05), there were no significant differences in other factors such as age, disease duration, medication, ESR, CRP, DAS28, etc., among the three groups.However, RA patients who were ACPA + did have higher median counts of swollen and tender joints and higher DAS 28 scores (as indicated in Table 1).