Anti-CCP
Xchange newsletter – May 2009
Anti-cyclic citrullinated peptide (anti-CCP) is one of several tests available to diagnose the chronic, systemic, autoimmune disease Rheumatoid Arthritis (RA). Following the introduction of new clinical guidelines on the management of RA [1], we take a fresh look at the value anti-CCP testing adds to patient care.
Diagnosis of RA is based on clinical symptoms as well as laboratory findings, and patients with RA frequently have a positive Rheumatoid Factor (RF), elevated Erythrocyte Sedimentation Rate and C-reactive protein, and antibodies to CCP peptides [2,3].
Although RF remains a front line laboratory diagnostic test, it has been well documented that the test is not ideal and must not be used in isolation to make an accurate diagnosis. RF is known to be positive in other situations (infections, the elderly) and is also known to be negative in some people with classical clinical symptoms of RA [3].
An elevated anti-CCP is often seen in the early stages of RA in combination with a negative RF. Anti-CCP may also be helpful to distinguish patients with arthritic symptoms who do not necessarily meet the full criteria of the autoimmune cause of arthritis. The presence of anti-CCP in patients with an undifferentiated polyarthritis is an indication of the likely development of the autoimmune RA [3].
Abbott’s ARCHITECT anti-CCP assay is an automated two-step chemiluminescent microparticle immunoassay (CMIA) with automated pretreatment. The dynamic range of the assay is 0.5– 200.0 U/mL without dilution, and the analytical sensitivity is </= 0.5 U/mL. The clinical specificity is 98.2%, with a result of >/= 5.0 U/mL considered positive and a result of <5.0 U/mL considered negative [6].
In February, NICE launched clinical guideline 79 ‘Rheumatoid arthritis: The management of rheumatoid arthritis in adults’ [1]. NICE recommends that anti-CCP antibodies can be measured in all patients presenting with suspected RA where a negative RF has been found. Early detection, diagnosis and subsequent treatment of RA can minimise the associated tissue damage arising from the inflammatory response and increased circulating cytokines.
Anti-CCP is able to offer an earlier diagnosis of RA than RF alone, and can differentiate the patients who already have other forms of arthritis that are likely to go on to develop RA as a secondary condition [4,5].
Once a firm diagnosis of RA has been made, several medication routes are available, and the choice of therapy is made based on the severity of the symptoms, the progression of the disease itself, and the tolerance of the patient to certain medications.
[1] CG79 Rheumatoid Arthritis NICE Guideline, Feb 2009
[2] www.rheumatoid.org.uk
[3] www.labtestsonline.org.uk
[4] Fabien N et al, Presse Med. 2008;37(12)
[5] Jansen et al. J Rheumatol 2002; 29
[6] ARCHITECT Anti-CCP package insert, Nov 2008
[7] www.netdoctor.co.uk/medicines/100005107.html
[8] www.humira.com
Front view of a human knee joint affected by rheumatoid arthritis. The knee cap (patella, yellow) is at upper centre, between the thigh bone (femur, above), and the shin bone (tibia) and fibula (below). The protective layer of cartilage (pink) covering the joint has worn away in patches. The fibrous pink tissues are tendons and ligaments, which hold muscles and bones together inside joints. © Science Photo Library
