Dana Mohammed Tofiq*, Khalida M. Mousawy ** and Raouf Rahim Mirza ***

*   Department of Microbiology, School of Medicine, Faculty of Medical Sciences, University of Sulaimani.

**  Department of Microbiology, College of Medicine, University of Baghdad.

*** Department of Medicine, School of Medicine, Faculty of Medical Sciences, University of Sulaimani.

Submitted: 5/2/2012; Accepted: 15/4/2012; Published 1/12/2012

DOI Link: https://doi.org/10.17656/jsmc.10022 



As modern treatment of rheumatoid arthritis is shifting toward aggressive anti-rheumatic therapy in an early phase of the disease to prevent the progression of joint damage (which is irreversible), diagnostic tests with high specificity are desirable.


To compare the diagnostic value (sensitivity and specificity) of the three tests (anti-cyclic citrullinated peptide antibodies, rheumatoid factors IgM and IgA) in rheumatoid arthritis; to determine the test which gives the best combination of diagnostic sensitivity and specificity.

Patients and Methods

There were 47 rheumatoid patients, 16 scleroderma patients and 26 apparently healthy peoples, which were enrolled voluntarily in the study. Blood samples were taken from the three groups and analyzed to measure the serum levels of the three diagnostic tests.


The sensitivities of the three tests were as the following: anti-cyclic citrullinated peptide antibodies 68.1%, rheumatoid factor IgM 78.7% and rheumatoid factor IgA 72.3%. There were no significant differences in sensitivities of the three tests and nearly all had the same sensitivity. The specificities of the three tests were as the following: anti-cyclic citrullinated peptide antibodies 97.6%, rheumatoid factor IgM 83.3% and rheumatoid factor IgA 90.5%. The specificity of anti-cyclic citrullinated peptide antibodies was significantly higher than rheumatoid factor IgM. There were no significant differences between the specificities of anti- cyclic citrullinated peptide antibodies and rheumatoid factor IgA, rheumatoid factor IgM and rheumatoid factor IgA. Therefore, the anti-cyclic citrullinated peptide antibodies give the best specificity among the three diagnostic tests; and they were positive in 40% of seronegative (rheumatoid factor IgM negative) rheumatoid patients.


Anti-cyclic citrullinated peptide antibodies are useful tools in the diagnosis of rheumatoid arthritis, as they are comparably sensitive as the rheumatoid factors but they have the advantage of possessing excellent specificity. Also they have an additional diagnostic value, as they are positive in 40% of seronegative rheumatoid patients.


Anti-cyclic citrullinated peptide antibodies, Rheumatoid factor IgM, Rheumatoid factor IgA.


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