Comparison of anti-cyclic citrullinated peptide(CCP) antibody and rheumatoid factor for diagnosis of rheumatoid arthritis in a tertiary care, Kathmandu, Nepal.

Thesis Report.

ABSTRACT:

Background
Rheumatoid arthritis (RA) is a systemic inflammatory and autoimmune disease that
affect many tissues, organ and system but primarily attacking joints. Many auto
antibodies like Anti Perinuclear Factor (APF), Anti Keratin Antibodies (AKA) have
been reported to diagnose RA. Rheumatoid factor (RF) and anti-cyclic citrullinated
peptide antibody have important diagnostic value and are predictor of functional
radiographic outcomes. RF is highly sensitive serological marker for the diagnosis of
RA but not specific which is present in various disease and even in up to 15% of healthy
population. Anti CCP antibody is another serological marker which has high specificity
than RF for the diagnosis of RA which is even present in pre- clinical stage and sero-
negative rheumatoid arthritis patients.

Aim of study: To compare the diagnostic performance of rheumatoid factor (RF) and
anti-cyclic citrullinated peptide antibody (anti-CCP) in the diagnosis of patients with
rheumatoid arthritis (RA) in Taiwan.

METHOD
It was a cross-sectional hospital based study, we included 330 patients that will be
conducted in the Virology/Immunology laboratory of Department of Microbiology, and
Department of Internal medicine (Rheumatology), TUTH. We included 330 patients
whose specimens is collected for the diagnosis of rheumatoid arthritis visiting
Rheumatology OPD will be analyzed by latex agglutination method for RF and Enzyme
linked Immunosorbent Assay (ELISA) method for anti CCP (IgG) antibody. The required procedures will be done according to the standard microbiological protocol and
the guideline provided by manufacturer of the kit.

RESULT
Three hundred and thirty clinically diagnosed RA patients comprising 86 male and 244
female were taken for this study. Out of 330 patients, 56 (16.97) were anti-CCP
antibodies positive and 274 (83.03%) were negative for anti-CCP antibodies and
comparison between anti-CCP antibodies positive and anti-CCP antibodies negative
were statistically significant P<0.038. Among 330 clinically diagnosed RA patients, 80
were RF positive and 250 were diagnosed as RF negative. Among RF positive patients,
45 (56.25%) were positive for anti-CCP antibody and among RF negative patients,
11(4.4%) were positive for anti CCP antibody and the comparison between anti-CCP
antibody and RF was statistically significant (P<0.038).

Conclusion
The RF and anti-CCP tests are complementary, and the co-detection of these antibodies
can increase the detection rate and provide important clinical value in the diagnosis of
RA. Both anti-CCP and RF positivity are useful for the diagnosis of RA, and use of both
tests together improves the diagnostic sensitivity. However, Anti-CCP antibodies are an
excellent serological marker for RA, which shows high diagnostic specificity at early
stage and detection of IgM RF is good predictor for disease severity.