The diagnostic utility of the anti-CCP antibody test is no better than rheumatoid factor in South Africans with early rheumatoid arthritis

Abstract

To establish the diagnostic utility of the anticyclic-citrullinated peptide antibody (aCCP) test in Black South Africans with early rheumatoid arthritis (RA). A cross-sectional study comparing the rheumatoid factor (RF) and aCCP status in RA patients and a control group consisting of healthy subjects, and patients with systemic lupus erythematosus (SLE) and scleroderma. The sensitivity, specificity, positive (PPV) and negative predictive values of the aCCP test alone were 82.5%, 84.9%, 87.6% and 79% versus 81.7%, 90.7%, 92.5% and 78% for RF alone. The best specificity (95.3) and PPV (95.8%) was observed when both aCCP and RF tests were positive. Patients with erosive disease had a significantly higher mean RF titre compared with those with non-erosive disease (p=0.007). There was a trend towards an association of smoking (OR=4.1, 95% CI=0.9-18.6) and functional disability (p=0.07) with RF-positive status. No similar clinical associations were observed with aCCP. Almost a third of SLE patients were aCCP positive. Despite the best specificity and PPV observed when both the aCCP and RF tests were positive, our findings suggest that testing for aCCP is only cost-effective in the RF-negative patient in whom there is a strong clinical suspicion of RA.

HLA-DRB1 shared epitope genotyping using the revised classification and its association with circulating autoantibodies, acute phase reactants, cytokines and clinical indices of disease activity in a cohort of South African rheumatoid arthritis patients

“…In addition, in agreement with previous European and Japanese RA cohort studies [19,40], we observed highly significant associations of SS and SX with seropositivity for aCCP but not RF [21,40]. We have previously reported that isolated measurement of aCCP is no more accurate than RF in the serodiagnosis of RA [41]. However, when used in combination with SE genotyping, measurement of aCCP appears to distinguish a subset of patients who may differ with respect to response to therapy and outcome.…”

A Comparative Assessment of the Diagnostic Value of Anti-cyclic Citrullinated Peptide Antibodies and Rheumatoid Factor in Rheumatoid Arthritis

“…In our study the sensitivity and specificity of RF were 46.2 and 90.29%, respectively. These values are similar to those reported by Aflaki using latex fixation test [9] but are different from Hodkinson's study [15]. A literature review shows that the sensitivity of RF in RA has ranged from 26 to 90 percent [16].…”

Systemic Autoimmune Diseases: Not So Rare in Black Africans

“…A previous rheumatoid factor estimation among black South Africans showed a positivity of 12.1% [4], though a more recent study showed similar frequency with Caucasians [16]. Anti-CCP was seen in only 48.6% of cases of RA from DRC [17]. Although anti-CCP is said to be more specific and sensitive than rheumatoid factor, Hodkinson et al in a report from South Africa concluded that the diagnostic ability of anti-CCP is no better than rheumatoid factor in South Africans with early RA.…”