Evaluation of an automated connective tissue disease screening assay in Korean patients with systemic rheumatic diseases

Abstract

This study aimed to evaluate the diagnostic utilities of the automated connective tissues disease screening assay, CTD screen, in patients with systemic rheumatic diseases. A total of 1093 serum samples were assayed using CTD screen and indirect immunofluorescent (IIF) methods. Among them, 162 were diagnosed with systemic rheumatic disease, including rheumatoid arthritis (RA), systemic lupus erythematosus (SLE), and mixed connective tissue disease (MCT). The remaining 931 with non-systemic rheumatic disease were assigned to the control group. The median ratios of CTD screen tests were significantly higher in the systemic rheumatic disease group than in the control group. The positive likelihood ratios of the CTD screen were higher than those of IIF in patients with total rheumatic diseases (4.1 vs. 1.6), including SLE (24.3 vs. 10.7). The areas under the receiver operating characteristic curves (ROC-AUCs) of the CTD screen for discriminating total rheumatic diseases, RA, SLE, and MCT from controls were 0.68, 0.56, 0.92 and 0.80, respectively. The ROC-AUCs of the combinations with IIF were significantly higher in patients with total rheumatic diseases (0.72) and MCT (0.85) than in those of the CTD screen alone. Multivariate analysis indicated that both the CTD screen and IIF were independent variables for predicting systemic rheumatic disease. CTD screen alone and in combination with IIF were a valuable diagnostic tool for predicting systemic rheumatic diseases, particularly for SLE.

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

“…The serum samples were diluted with phosphate-buffered saline to a 1 : 40 ratio. The procedures for IIF were conducted as described previously [ 15 ].…”

“…Testing with the CTD screen (Phadia AB) was conducted on a Phadia 250 instrument (Phadia AB). The assays were conducted according to the manufacturer's instructions, as described before [ 15 , 16 ]. The previously applied cutoffs were also used in this study; cutoffs greater than 1.0 were considered positive, ratios ranging from 0.7 to 1.0 were equivocal, and values less than 0.7 were negative.…”

“…Statistical analyses were performed using PASW software, version 24.0 (formerly, SPSS Statistics) (SPSS Inc., Chicago, IL, USA) and Analyse-it Method Evaluation Edition software, version 2.26 (Analyse-it Software Ltd., Leeds, UK). Comparisons using chi-squared test and the Mann–Whitney U test were performed as described before [ 15 ]. Cohen's kappa coefficients were calculated to estimate the agreement among the results of the CTD screen and the other three autoantibody assays, and McNemar's test was also conducted.…”

“…The areas under the ROC curves (ROC-AUCs) for the CTD screen and its combination with the other three assays were compared. Binary logistic regression analysis was performed to estimate the ROC-AUCs for IIF and CTD screen combinations, similar to the previously described method [ 15 , 18 ]. Multivariate logistic regression analysis was performed by setting the presence of an AARD as the dependent variable and age, sex, and the results of IIF, CTD screen, EliA ENA, and LIA testing as covariables.…”

High Seroprevalence of Autoantibodies Typical of Autoimmune Liver Disease in Eastern Ethiopia: Is Chewing of Khat (Catha edulis) a Triggering Factor?

“…Autoimmune markers were determined by the Phadia™250 Laboratory system (Thermo Fisher Scientific, Waltham, MA, USA). ANA was detected using the EliA™ Symphony assay (Phadia, Freiburg, Germany) with a calculated ratio of test sample response to calibrator >1.0 defined as positive, 0.7-1.0 was equivocal, and <0.7 was negative [22, 23]; SMA was determined by QUANTA Lite® Actin IgG (Inova Diagnostics, San Diego, CA, USA) and a cut-off level >30 assay units was classified as positive, as proposed by the manufacturer [24]; AMA was determined using QUANTA Lite® M2 EP (MIT3) (Inova Diagnostics) and a cut-off level >25 assay units was classified as positive, as proposed by the manufacturer [25]. Serum was analysed for IgG using the IMMAGE® 800 Immunochemistry System (Beckman Coulter, Brea, CA, USA) and serum alkaline phosphatase (ALP) activity was measured using ARCHITECT ci16200 (Abbott Diagnostics, Abbott Park, IL, USA).…”