The Performance Of a Point Of Care Test For Detection Of Anti-Mutated Citrullinated Vimentin and Rheumatoid Factor In Early Rheumatoid Arthritis

Preeda Rojanasantikul¹, Prapa Pattrapornpisut², Kulvara Anuruckparadorn³ and Wanruchada Katchamart¹, ¹Division of Rheumatology, Department of Internal Medicine, Siriraj Hospital, Mahidol University, Bangkok, Thailand, ²Department of Internal Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand, ³Department of Transfusion Medicine, Siriraj Hospital, Mahidol University, Bangkok, Thailand

Meeting: 2013 ACR/ARHP Annual Meeting

Keywords: Anti-citrullinated protein/peptide antibodies (ACPA) and rheumatoid arthritis (RA), Diagnostic Tests, Rheumatoid Factor

Session Information

Title: Health Services Research, Quality Measures and Quality of Care-Rheumatoid Arthritis

Session Type: Abstract Submissions (ACR)

Background/Purpose:

Besides rheumatoid factor (RF), anti-cyclic citrullinated peptide antibody (ACPA), a newer serologic marker, was added to the new American College of Rheumatology (ACR)/European League Against Rheumatism (EULAR) classification criteria 2010. Most commercially available assay used for detection of ACPA and RF is the ELISA-based method. This assay is a multi-step and time-consuming procedure requiring special equipments and experienced technicians. ACPA therefore may not be available worldwide. Moreover, the results of these tests may take too long to be of value in daily practice, leading to delayed diagnosis. Recently, a serological point-of-care test (POCT) for detection of anti-MCV and RF using a lateral flow immunochromatographic assay (LFIA) has been developed for a rapid result, and it also has wider availability. The diagnostic performance of this POCT was documented in established RA; however, its performance in patients with ‘early’ RA is still unknown. Our objective was to determine the diagnostic performance of a point of care test (POCT) for detection of anti-mutated citrullinated vimentin (MCV) and rheumatoid factor (RF) in early rheumatoid arthritis (RA) with 2 years of disease duration or less. Additionally, we evaluated the agreement of these tests when using EDTA whole blood and capillary blood.

Methods: Patients with RA and other rheumatic disorders were consecutively recruited from the Rheumatology outpatient clinic. The POCT for detection of anti-MCV and RF using capillary blood and EDTA whole blood was performed in 78 patients with early RA, 55 patients with other rheumatic disorders, and 55 healthy blood donors.

Results: The sensitivity and specificity of anti-MCV POCT in patients with early RA were 64% and 97%, respectively, while the sensitivity and specificity of RF POCT were 51% and 95% respectively. The positive likelihood ratio of the POCT for anti-MCV was higher than those for RF (23.5 vs.9.4). The negative likelihood was 0.37 for anti-MCV and 0.52 for RF. There were 3 cases with false positive for anti-MCV including a patient with psoriatic arthritis and the other two with systemic sclerosis. The agreement between capillary blood and EDTA whole blood testing for anti-MCV and RF was low to moderate with Cohen’s kappa of 0.58 and 0.49, respectively.

Conclusion: This POCT for detection of anti-MCV and RF yielded high specificity and may be a valuable tool for the diagnosis of early RA. Using this POCT with EDTA whole blood instead of capillary blood is not recommended.

Disclosure:

P. Rojanasantikul,
None;

P. Pattrapornpisut,
None;

K. Anuruckparadorn,
None;

W. Katchamart,
None.

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