Evaluation of an Automated Screening Assay, Compared to Indirect Immunofluorescence, an Extractable Nuclear Antigen Assay, and a Line Immunoassay in a Large Cohort of Asian Patients with Antinuclear Antibody-Associated Rheumatoid Diseases: A Multicenter Retrospective Study

Abstract

We assessed the diagnostic utility of the connective tissue disease (CTD) screen as an automated screening test, in comparison with the indirect immunofluorescence (IIF), EliA extractable nuclear antigen (ENA), and line immunoassay (LIA) for patients with antinuclear antibody- (ANA-) associated rheumatoid disease (AARD). A total of 1115 serum samples from two university hospitals were assayed using these four autoantibody-based methods. The AARD group consisted of patients with systemic lupus erythematosus (SLE), systemic sclerosis (SSc), Sjögren's syndrome (SS), and mixed connective tissue disease (MCTD). The qualitative results of all four autoantibody assays showed a significant association with AARDs, compared to controls (P < 0.0001 for all). The areas under the receiver operating characteristic curves (ROC-AUCs) of the CTD screen for differentiating total AARDs, SLE, SSc, SS, and MCTD from controls were 0.89, 0.93, 0.73, 0.93, and 0.95, respectively. The ROC-AUCs of combination testing with LIA were slightly higher in patients with AARDs (0.92) than those of CTD screen alone. Multivariate analysis indicated that all four autoantibody assays could independently predict AARDs. CTD screening alone and in combination with IIF, EliA ENA, and LIA are potentially valuable diagnostic approaches for predicting AARDs. Combining CTD screen with LIA might be effective for AARD patients.

Relationships among Antibodies against Extractable Nuclear Antigens, Antinuclear Antibodies, and Autoimmune Diseases in a Brazilian Public Hospital

“…Our results demonstrated that 76.9% of the anti-ENA-positive patients were in the highest ANA titer range, and 84.6% of patients who were anti-ENA- and ANA-positive were diagnosed with an AD. This result is very similar to that reported by Jeong [ 30 ], who used an anti-ENA test with the same methodology (line immunoassay) and found 83.9% positivity in ANA and anti-ENA tests in a cohort of Asian patients with AD. A study in Bangladesh [ 31 ] showed autoimmune diseases in 85.5% of double positivity (ENA and ANA tests), working with dot-blot methodology for ENA detection.…”

“…Chandratilleke et al [ 12 ] compared LIA with an automatized fluorescent assay (FIDIS) in 529 samples and found a 90.5% concordance. A work conducted in Korea [ 30 ], with patients with AD, showed a similar performance among three anti-ENA methods (two automatized immunoenzymatic assays and LIA). Vercammen et al [ 39 ] analyzed 174 ANA-positive samples by immunodiffusion, LIA, and an automatized fluorescent immunodetection methodology, showing no difference between them.…”

“…The methodology used in this objective is important, as Kidd [ 34 ] argued that samples that were previously negative turned out to be positive when subjected to another analysis with a different methodology. Finally, the association of different techniques ensures greater sensitivity and specificity [ 30 ].…”

“…Previous studies conducted by Albon et al [ 55 ] and Vercammen et al [ 39 ] have compared several methods of ENA testing and shown overall equivalence for most antigens. However, unlike the approach of this study, recruitment in these studies and others [ 30 , 31 , 56 ] was based on patients with known diseases or a positive ANA, which alters the pretest probability of a positive ENA test.…”

Challenges and Advances in SLE Autoantibody Detection and Interpretation

“…For the most part, SPMAAs are widely available and are currently used either as an approach to the diagnosis of specific SARDs (i.e., separate SLE, scleroderma (SSc), Sjögren's syndrome (SjS), autoimmune inflammatory myopathy (AIM) profiles), and/or the most common targets seen in SARDs included in a SARD screen as an alternative to the ANA IFA. However, there is some evidence that while SPMAA are a significant move forward, combining ANA IFA with SPMAA has higher clinical impact than either of the tests alone [3,20,36,42,43]. SLE serum samples that have negative SPMAA test results should ideally be tested by ANA IFA to determine if antibodies to targets not included in the SPMAA are detected.…”