The diagnostic accuracy of anti-citrullin antibody assessment in the diagnosis of patients suspected of rheumatoid arthritis by a general practitioner
Boer, A.K.; Weekamp, H.H.; van der Lugt, C.P.; van de Laar, M.A.F.J.; van der Sluijs Veer, G.
Nederlands Tijdschrift Voor Geneeskunde 152(2): 91-95
2008
ISSN/ISBN: 0028-2162 PMID: 18265799 Document Number: 618947
To determine whether assessment of antibodies directed against citrullin provides additional value in the diagnosis of rheumatoid arthritis (RA) in general practice. Retrospective. In a 6-month period in 2004 (May-December), all sera sent to our laboratory for assessment of rheumatoid factor (RF-IgM), were also analysed for the presence of antibodies directed against citrullinated fibrinogen (anti-citrullin). We analysed 691 sera sent in by general practitioners using a homemade assay. To determine the disease classification, general practitioners were asked to provide information pertaining to the American College of Rheumatology disease classification criteria. The response was 97.6%. For patients who were referred to a rheumatologist in the last 2 years (December 2004-December 2006), the diagnosis of the rheumatologist was also considered in the analysis. A total of 28 patients (4%) were diagnosed with rheumatoid arthritis. Only 25% of these patients were positive for anti-citrullin, and only 25% were positive for RF-IgM. These 2 groups only partially overlapped. The positive and negative predictive values of anti-citrullin were 36 and 96%, respectively. The presence of anti-citrullin provided no additional value compared to rheumatoid factor in classifying RA in a general practice population.