Analytical and Diagnostic Characteristics of 11 2Nd- and 3Rd-Generation Immunoenzymatic Methods for the Detection of Antibodies to Citrullinated Proteins (Clinical Immunology‪)‬

Antibodies to citrullinated proteins (CPs) [5] are markers for rheumatoid arthritis (RA), especially for early diagnosis of the disease. In some cases these antibodies may be detected many years before the onset of the first symptoms (1, 2). In addition, their presence at disease onset has a high positive predictive value for the development of erosive joint lesions (3), and the detection of these antibodies can therefore be used in clinical practice to help plan a therapeutic strategy (4, 5). Moreover, in view of the high specificity of these antibodies, the test is particularly useful in differential diagnosis between RA and other arthritides that are clinically similar to RA and may be positive for rheumatoid factor (RF), such as hepatitis C virus (HCV)-associated cryoglobulinemia (6, 7), undifferentiated polyarthritis (8), or Sjbgren syndrome (9, 10). The presence of anti-CP antibodies has already been proposed for inclusion among the classification/diagnostic criteria for RA (4, 11). The increased demand for the test has led several manufacturers to develop reagent sets, and many enzymatic immunoassay (EIA) methods employing different CPs are now commercially available. Although all these methods use CPs, they differ in terms of the antigen source and the characteristics of the analytical method.