Are you using the "signal light" for rheumatoid arthritis and joint damage correctly to fight against CCP?

Anti-cyclic citrullinated peptide antibody (CCP) is a polypeptide fragment of cyclic filaggrin, and is mainly an IgG type antibody. It has good sensitivity and specificity for rheumatoid arthritis (RA). So what is its relationship with rheumatoid arthritis?

Anti-CCP existence time

Like rheumatoid factor (RF), CCP may be present before RA symptoms appear.

The relationship between anti-CCP and treatment

Patients who are effectively treated may experience a decrease in CCP titer, especially if they are treated with non-biological or biological disease-modifying antirheumatic drugs (DMARDs) in the early stages, but the incidence and magnitude of the decrease are not as high as those of IgM RF.

Anti-CCP positivity in other diseases

Although CCP is more specific than RF for diagnosing RA, positive results can occur in other diseases, including several autoimmune rheumatic diseases, tuberculosis, and sometimes chronic lung disease (see below).

Anti-CCP and the prognosis of RA

Early RA patients with positive CCP are at increased risk for progressive joint damage. CCP testing may be more effective than RF testing in predicting erosive disease.

Patients with early oligoarthritis or polyarthritis who were negative for IgM RF but became CCP-positive also had an increased risk of radiological progression. The incidence of radiological progression (Sharp score greater than 5) was higher in CCP-positive patients than in CCP-negative patients (40% vs 5%). Anti-CCP testing accurately predicted whether 83% of patients would have progressively worsening radiological damage.

Anti-CCP positivity in other diseases

1) Anti-CCP antibodies have been reported in SLE and primary SS, usually with teratogenic or erosive arthritis. For example, one study showed that 17% of a cohort of 335 SLE patients were anti-CCP positive, and another study showed that 10% of 155 consecutive primary SS patients were anti-CCP positive.

However, in these cases, some experts have suggested that such patients should be reclassified as SLE-RA and primary SS/RA overlap syndrome, respectively. Similar findings have also been reported in patients with psoriatic arthritis.

2) Patients with active tuberculosis (TB) have been found to have an increased prevalence of anti-CCP antibodies. The prevalence reported in different studies varies, ranging from as high as 32%-39% to as low as 7%.

3) In contrast to RF, anti-CCP antibodies are rarely found in the sera of patients infected with hepatitis C virus (HCV).

4) Among patients with chronic obstructive pulmonary disease, the detection rate of anti-CCP antibodies is 3-5%.