Arthritis & Rheumatism, Volume 62,
November 2010 Abstract Supplement
Abstracts of the American College of
Rheumatology/Association of Rheumatology Health Professionals
Annual Scientific Meeting
Atlanta, Georgia November 6-11, 2010.
A Novel Diagnostic Marker for RA, Anti-MCV.
Zablocki1, Rong W., Van der Helm-van Mil3, Annette, Huizinga3, Tom, Rao2, Srinivas
Early identification of undifferentiated arthritis (UA) patients at greatest risk for developing rheumatoid arthritis (RA) may facilitate better treatment. Rheumatoid factor (RF IgM) and antibodies against cyclic citrullinated peptide (anti-CCP) are widely used in diagnosing RA. It has been suggested that the enzyme-linked immunosorbent assay (ELISA) to detect mutated, citrullinated vimentin (anti-MCV) may have a different diagnostic spectrum versus anti-CCP. The purpose of the current study was to evaluate the diagnostic performance of combinations of these biomarkers in UA-RA patients.
Clinical and laboratory data were analyzed from a 470 patient subset of the previously described 570 patient Leiden Early Arthritic Clinic cohort (A. Van der Helm-van Mil, et al., 2007). These patients presented with UA, and a fraction (n=153) progressed to RA within 1 year, based on the fulfillment of the American College of Rheumatology (ACR) criteria. Anti-MCV, Anti-CCP2 and RF IgM tests were performed. A positive result for a combination was defined as resulting when all constituents were positive; a negative result of any constituent was defined as the combination negative. The sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV), as well as their 95% confidence intervals (CI), were calculated for each individual biomarker as well as their combinations.
Table 1 presented the diagnostic performance of the biomarkers and their combinations. Overall, anti-MCV demonstrated the highest sensitivity (63%) and NPV (82%), though at the cost of reduced PPV (60%). Combining Anti-CCP2 and Anti-MCV barely reduced sensitivity comparing to Anti-CCP2 alone (52% vs. 53%), and exhibited a favorable balance in sensitivity/specificity and in PPV/NPV. Further, the sensitivity diagram (at right) revealed that anti-CCP2 did not provide additional information (sensitivity=0%) in the context of both RF IgM and anti-MCV being positive. However, anti-MCV and RF IgM still respectively retained 10% and 5% sensitivity despite positivity of the other 2 assays.
Anti-MCV showed the highest sensitivity and NPV. Nearly all Anti-CCP2 positive RA patients were also Anti-MCV positive, though not vice versa, reinforcing the notion that the diagnostic spectrum of the 2 assays is not identical. In the context of positive results for both anti-MCV and RF IgM, anti-CCP2 became redundant in term of sensitivity. In summary, incorporating anti-MCV as an adjunctive diagnostic tool to prognosticate future RA in patients who present with UA enhances sensitivity.
To cite this abstract, please use the following information:
Zablocki, Rong W., Van der Helm-van Mil, Annette, Huizinga, Tom, Rao, Srinivas; A Novel Diagnostic Marker for RA, Anti-MCV. [abstract]. Arthritis Rheum 2010;62 Suppl 10 :660