[The diagnostic accuracy of anti-citrullin antibody assessment in the diagnosis of patients suspected of rheumatoid arthritis by a general practitioner].
OBJECTIVE
To determine whether assessment of antibodies directed against citrullin provides additional value in the diagnosis of rheumatoid arthritis (RA) in general practice.


METHODS
Retrospective.


METHODS
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.


RESULTS
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.


CONCLUSIONS
The presence of anti-citrullin provided no additional value compared to rheumatoid factor in classifying RA in a general practice population.
Boer
A K
AK
Medisch Spectrum Twente, Enschede.
Weekamp
H H
HH
van der Lugt
C P
CP
van de Laar
M A F J
MA
van der Sluijs Veer
G
G
D000974:Antibodies, Antinuclear / Q000097:blood*; D001172:Arthritis, Rheumatoid / Q000097:blood / Q000175:diagnosis*; D002956:Citrulline / Q000276:immunology*; D003937:Diagnosis, Differential; D005194:Family Practice / Q000379:methods* / Q000592:standards; D006801:Humans; D007075:Immunoglobulin M / Q000276:immunology; D012189:Retrospective Studies; D012217:Rheumatoid Factor / Q000097:blood; D012680:Sensitivity and Specificity
D000974:Antibodies, Antinuclear; D007075:Immunoglobulin M; D002956:Citrulline; D012217:Rheumatoid Factor