No, the test order should specify anti-CCP testing
If you are evaluating a patient for rheumatoid arthritis or undifferentiated peripheral inflammatory arthritis, you should explicitly order anti-CCP (or ACPA) testing along with rheumatoid factor, as both are strongly recommended for diagnosis and prognosis. 1
Why Anti-CCP Testing is Essential
The evidence-based guidelines are clear: Testing of rheumatoid factor (RF) and/or ACPA (anti-citrullinated protein antibodies, which includes anti-CCP) should be performed in the evaluation of patients with undifferentiated peripheral inflammatory arthritis. 1 These markers are:
- Predictive of RA diagnosis - The association with RA at follow-up is compelling
- Predictive of prognosis - They increase probability of persistent synovitis and worse radiographic outcomes
- Highly specific - Anti-CCP has >95% specificity for RA versus <90% for RF alone 2
- Comparable sensitivity - Both achieve >70% sensitivity 2
The Term "ACPA" vs "Anti-CCP"
The guidelines deliberately use the general term "ACPA" because it encompasses multiple test generations (anti-CCP1, anti-CCP2, and newer versions). 1 However, in clinical practice, "anti-CCP" is the standard test name that laboratories recognize and perform. When you order "anti-CCP," you are ordering an ACPA test.
Critical Caveats
- Negative tests do not exclude RA - About 30% of RA patients are seronegative 1
- IgG is the standard isotype - While IgA anti-CCP exists and may indicate more severe disease 3, the standard diagnostic test measures IgG anti-CCP
- Rare false positives - Anti-streptavidin IgG antibodies can cause false-positive results in some assay platforms (0.6% prevalence), though this is uncommon 4
Bottom Line
Don't leave it ambiguous. Explicitly order "anti-CCP antibody" (or "anti-CCP IgG") on your requisition to ensure proper diagnostic workup for RA, as this testing directly impacts patient outcomes through earlier diagnosis and treatment initiation. 2