Rheumatology: Current Research
Open Access

Abstract

Anti-Citrullinated Albumin Antibodies as Biomarker for the Diagnosis of Rheumatoid Arthritis

Vishnupriya R Paturi, Ramakrishna R Uppuluri, Lina Gao, Charles T Roberts and Srinivasa R Nagalla*

Objective: Rheumatoid Arthritis (RA) is associated with increased levels of citrullinated proteins in synovial fluid and blood. Detection of Anticitrullinated Cyclic Peptide Antibodies (ACPA) is the current standard test for diagnosis of RA in conjunction with clinical symptoms. In addition to ACPA, antibodies to citrullinated human serum albumin (ACA) have been previously reported in individuals with RA. We developed a Point-Of-Care (POC) test for ACA and evaluated its sensitivity and specificity in healthy subjects and subjects with clinically diagnosed RA and other rheumatic conditions and autoimmune disease.

Methods: The ACA POC test is a lateral-flow immunoassay using antihuman IgA/G/M and anti-human serum albumin antibodies for detection of citrullinated serum albumin-ACA complexes. This test was used to determine serum or plasma ACA levels in a South Asian study population comprised of healthy controls (n=484) and subjects with clinically diagnosed RA (n=354) or other rheumatic (n=103) and autoimmune diseases (n=60) and compared to the levels of ACPA and Rheumatoid Factor (RF).

Results: The sensitivity of the ACA POC test for RA was 0.520 and the specificity was 0.994. ACA prevalence in other rheumatoid disease was similar to that of ACPA and less than that of RF. ACA was detected in 12% of RA samples that were negative for ACPA. The combined sensitivity of ACA+ACPA was 0.664 and the combined specificity was 0.845.

Conclusion: The ACA POC test exhibits robust sensitivity and specificity for RA diagnosis in serum or plasma and, in conjunction with ACPA, can enable the rapid and efficient differential diagnosis of RA with increased sensitivity and with comparable specificity.

Published Date: 2023-02-05; Received Date: 2024-01-04