Clinical Significance of Autoimmune Tests

Anti-CCP antibody measurements are valuable tools that can aid in the diagnosis of RA and predict the development of the disease; they are associated with disease progression and more severe disease. Anti-CCP measurements facilitate early diagnosis of RA, allowing for early initiation of therapy.

An aCCP antibody test may be ordered along with or following a rheumatoid factor (RF) test to help diagnose rheumatoid arthritis and to assess the severity and probable course of the disease (prognosis). CCP antibody may also be ordered to help evaluate the likely development of RA in people with undifferentiated arthritis – those whose symptoms suggest but do not yet meet the American College of Rheumatology (ACR) criteria for RA. According to ACR, approximately 95% of those with a positive CCP antibody will meet the criteria of RA in the future.¹

Both the American College of Rheumatology (ACR) and the European League Against Rheumatism Collaborative Initiative (EULAR) recommend the use of anti-CCP testing for RA classification and management of early arthritis.^2-3

The anti-CCP assay on the IMMULITE^® 2000/2000 XPi and ADVIA Centaur XP, CP, and XPT Systems offers excellent specificity for differential assessment of RA.

1. www.labtestsonline.org/understanding/analytes/ccp
2. EULAR recommendations for the management of early arthritis: report of a task force of the ESCISIT. Ann Rheum Dis 2007 66:34-45
3.2010 Rheumatoid Arthritis Classification Criteria. D Aletaha, T Neogi et al. Arthritis and Rheumatism, Vol 62, No. 9 September 2012. pp 2569-2581

The rheumatoid factor (RF) test is primarily used to help diagnose rheumatoid arthritis (RA) or Sjögren syndrome and to help distinguish them from other forms of arthritis or other conditions that cause similar symptoms. While diagnoses of RA and Sjögren syndrome rely heavily on the clinical picture, some of the signs and symptoms may not be present or follow a typical pattern, especially early in these diseases. Furthermore, the signs and symptoms may not always be clearly identifiable since people with these diseases may also have other connective tissue disorders or conditions, such as Raynaud's phenomenon, scleroderma, autoimmune thyroid disorders, and systemic lupus erythematosis, and display symptoms of these disorders as well*.

^{*http://labtestsonline.org/understanding/analytes/rheumatoid}

C-reactive protein (CRP) is a non-specific test. It may be used by a doctor to detect inflammation if there is a high suspicion of tissue injury or infection somewhere in the body, but the test cannot tell where the inflammation is or what condition is causing it. CRP is not diagnostic of any condition, but it can be used together with signs and symptoms and other tests to evaluate an individual for an acute or chronic inflammatory condition.*
For example, the CRP test is useful in monitoring people with chronic inflammatory conditions to detect flare-ups and/or to determine if treatment is effective.

Some examples include:

• Inflammatory bowel disease
• Some forms of arthritis
• Autoimmune diseases, such as lupus or vasculitis

It may also be ordered on a regular basis to monitor conditions such as rheumatoid arthritis and lupus and is often repeated at intervals to determine whether treatment is effective. This is particularly useful for inflammation problems since CRP levels drop as inflammation subsides.

^{*http://labtestsonline.org/understanding/analytes/crp}