ANTI-DFS70 ANTIBODIES DETECTED AS PART OF A PARTICLE BASED MULTI-ANALYTE TECHNOLOGY SYSTEM AIDS IN THE REFERRAL OF ANA POSITIVE INDIVIDUALS
- Kishore Malyavantham, United States of America
Abstract
Background and Aims
The referral of patients with positive anti-nuclear antibody (ANA) tests to tertiary care specialists has been criticized as an inappropriate use of medical resources thereby increasing the need to explore efficient testing methods. Here we assess the utility of a novel particle based multi-analyte technology (PMAT) in comparison to a chemiluminescent immunoassay (CIA) for the detection of anti-DFS70 antibodies.
Methods
Over a duration of three years, 15,357 patients were referred through a central triage (CT) system for review by tertiary care specialists. 643/15,357 (4.1%) were positive for HEp-2-ANA. 220/643 (34.2%) cases were tested using PMAT (centromere B, dsDNA, Jo-1, ribosomal-P, RNP, Ro60, Ro52, Scl-70, Sm, SSB, and DFS70) and CIA (QUANTA Flash, Inova Diagnostics, San Diego, CA) for anti-DFS70 antibodies.
Results
Out of the 220 ANA positive individuals, 52 (23.6%), 16 (7.3%) and 152 (69.1%) cases were defined as ANA-associated rheumatic disease (AARD), unresolved, or non-AARD cases, respectively. Out of 220 ANA positive cases, 48 (21.8%) and 42 (19.1%) were anti-DFS70 positive on PMAT and CIA, respectively [total percent agreement 95.5% [95%CI: 91.8-97.5]; kappa of 0.86 [95% CI 95% CI 77.8-94.3] and spearman’s rho 0.642). All 21 (9.5%) monospecific DFS70 positive were positive on CIA and a majority (20/21) of the cases were non-AARD, OR 6.9 [95% CI 1.1-41.3].
Conclusions
This is the first study to use PMAT to evaluate the serological and clinical features of patients referred through a CT system because of a positive ANA where PMAT and established CIA systems showed a high level of agreement for anti-DFS70 positivity.