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

Table 1

Demographic characteristics of the study population and the qualitative values for four autoantibody assays.

Variables		Total AARD ()	SLE ()	SSc ()	SS ()	MCTD ()	Control ()	value
Age (years)		39.0 (23.0–51.0)	37.0 (17.2–44.8)	39.0 (26.7–49.7)	54.0 (42.0–62.0)	43.0 (35.0–47.3)	50.0 (37.0–61.0)	<0.0001
Number of females, %		109, 97.3	66, 98.5	19, 90.5	19, 100.0	5, 100.0	995, 99.2	0.0561
CTD screen, cutoff ratio 0.7 (number), %	Positive	93, 83.0	58, 86.6	13, 61.9	17, 89.5	5, 100.0	100, 10.0	<0.0001
	Negative	19, 17.0	9, 13.4	8, 38.1	2, 10.5	0, 0.0	903, 90.0
CTD screen, cutoff ratio 1.0 (number), %	Positive	91, 81.3	57, 85.1	13, 61.9	16, 84.2	5, 100.0	79, 7.9	<0.0001
	Negative	21, 18.7	10, 14.9	8, 38.1	3, 15.8	0, 0.0.	924, 92.1
HEp-2 IIF (number), %	Positive	79, 70.5	51, 76.1	13, 61.9	11, 57.9	4, 80.0	99, 9.9	<0.0001
	Negative	33, 29.5	16, 23.9	8, 38.1	8, 42.1	1, 20.0	904, 90.1
EliA ENA (number), %	Positive	81, 72.3	51, 76.1	9, 42.9	17, 89.5	4, 80.0	93, 9.3	<0.0001
	Negative	31, 27.7	16, 23.9	12, 57.1	2, 10.5	1, 20.0	910, 90.7
LIA (number), %	Positive	94, 83.9	58, 86.6	14, 66.7	18, 94.7	4, 80.0	141, 14.1	<0.0001
	Negative	18, 16.1	9, 13.4	7, 33.3	1, 5.3	1, 20.0	862, 85.9

AARD: antinuclear antibody-associated rheumatoid disease; SLE: systemic lupus erythematosus; SSc: systemic sclerosis; SS: Sjögren’s syndrome; MCTD: mixed connective tissue disease; IIF: indirect immunofluorescence; ENA: extractable nuclear antigen; LIA: line immunoassay. Chi-squared test for nominal variables and Mann–Whitney test for continuous variables in the total AARD group versus control. Data are expressed as the median (1st to 3rd quartiles).