The study aimed to determine if testing for anti-CCP3 antibodies in patients who are negative for anti-CCP2 antibodies but have musculoskeletal symptoms could better predict the progression to inflammatory arthritis (IA) or rheumatoid arthritis (RA).

Researchers included 469 patients who were negative for anti-CCP2 antibodies and had new musculoskeletal symptoms. They tested these patients for anti-CCP3 antibodies and followed up after 12 months to check if their condition progressed to IA or RA. The doctors of patients who reported progression were contacted to confirm the diagnosis.


• The progression rate to IA/RA was low.
• 13% (61 out of 469) of participants reported disease progression, with most being diagnosed with IA.
• Only 3.4% (16 out of 469) were positive for anti-CCP3 antibodies.
• Anti-CCP3 positivity was associated with disease progression and IA diagnosis but not with RA.
• Anti-CCP3 levels were significantly different between those who progressed and those who did not.
• The sensitivity of anti-CCP3 for predicting progression was low, but specificity was high.
• Lowering the cut-off value for anti-CCP3 increased the odds of predicting disease progression.

Testing for anti-CCP3 antibodies could help predict the progression to IA/RA in patients who are negative for anti-CCP2 antibodies. More studies are needed to validate the best cut-off values for these predictions.