Swart A, Burlingame RW, Gürtler I, Mahler M. Third generation anti-citrullinated peptide antibody assay is a sensitive marker in rheumatoid factor negative rheumatoid arthritis.
Clin Chim Acta 2012;
414:266-72. [PMID:
23022338 DOI:
10.1016/j.cca.2012.09.015]
[Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2012] [Revised: 08/27/2012] [Accepted: 09/14/2012] [Indexed: 11/30/2022]
Abstract
INTRODUCTION
We compared 2 anti-citrullinated protein antibody (ACPA) assays using a routine patient cohort.
METHODS
Two-hundred ninety-five sera were collected from patients for whom ACPA was ordered and tested for ACPA by QUANTA Lite® CCP 3 (INOVA Diagnostics, Inc., San Diego) and EliA® CCP (CCP, Phadia, Germany). Rheumatoid factor (RF) was determined using Quantex RF(II) (Biokit, Spain).
RESULTS
Acceptable qualitative (96.6%, kappa=0.93) and quantitative agreements (Spearman rho=0.77; p<0.0001) were observed between the two ACPA assays. Nine samples were CCP3+/CCP2- and one sample was CCP2+/CCP3-. Of the 9 CCP3+/CCP2- patients, 6 (66.7%) had RA, one patient had ankylosing spondylitis, one osteoarthritis and one psoriatic arthritis. The CCP3-/CCP2+ patient had juvenile RA. At the manufacturer's cut-offs, the sensitivities and specificities were 77.3%/98.1% (CCP2), 81.6%/96.8% (CCP3) and 65.2%/89.6% (RF), respectively. At 98.7% specificity level, the sensitivities in the total cohort were 59.6% (CCP2) and 69.5% (CCP3) while the sensitivities in the RF-negative group were 49.0% (CCP2) and 57.1% (CCP3). In the RF-negative group, sensitivities for patients with a disease duration of ≤ 5years were 38.7% (CCP2) and 51.6% (CCP3).
CONCLUSION
Discrimination between RA and non-RA patients was better using CCP3, most pronounced in RF-negative RA.
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