N=961) Using Hep-2 (Cut-Off ≥1:40

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Supplementary Tables

Supplementary Table 1. Inter-test agreement for baseline ANA tests (n=961) using HEp-2 (cut-off 1:40) and mouse liver (cut-off 1:20) for 961 patients with various autoimmune rheumatic diseases Disease Patients HEp-2 (+) HEp-2 (+) HEp-2 (-) HEp-2 (-) ML (+) ML (-) ML (+) ML (-) n (%) n (%) n (%) n (%) SLE 418 242 (57.9) 84 (20.1) 12 (2.9) 80 (19.1)

DM/PM 20 11 (55.0) 2 (10.0) 0 (0) 7 (35.0)

RA 251 89 (35.5) 39 (15.5) 12 (4.8) 111 (44.2)

SS 89 33 (37.1) 25 (28.1) 2 (2.3) 29 (32.6)

MCTD 36 20 (55.6) 5 (13.9) 3 (8.3) 8 (22.2)

SSc 52 32 (61.5) 14 (26.9) 0 (0) 6 (11.5)

APS 16 8 (50.0) 2 (12.5) 0 (0) 6 (37.5)

Controls 79 20 (25.3) 11 (13.9) 6 (7.6) 42 (53.2)

Total 961 455 (47.4) 182 (18.9) 35 (3.6) 289 (30.1)

Abbreviations: (+) positive; (-) negative; APS, antiphospholipid syndrome; DM/PM,

dermatomyositis/polymyositis; MCTD, mixed connective tissue disease; ML, mouse liver; RA,

rheumatoid arthritis; SLE, systemic lupus erythematosus; SS, Sjögren’s syndrome; SSc, systemic

sclerosis.

Choi MY, et al. Lupus Sci Med 2020; 7:e000431. doi: 10.1136/lupus-2020-000431 BMJ Publishing Group Limited (BMJ) disclaims all liability and responsibility arising from any reliance Supplemental material placed on this supplemental material which has been supplied by the author(s) Lupus Sci Med

Supplementary Table 2. Inter-test agreement for baseline ANA tests (n=961) using HEp-2 (cut-off 1:80) and mouse liver (cut-off 1:80) for 961 patients with various autoimmune rheumatic diseases Disease Patients ANA HEp-2 ANA ML Agreement Kappa Standard P-value

Positive (%) Positive (%) (%) Error

SLE 418 216 (51.7) 172 (41.2) 85.7 0.71 0.05 <0.0001

DM/PM 20 9 (45.0) 8 (40.0) 85.0 0.69 0.22 0.001

RA 251 68 (27.1) 52 (20.7) 87.3 0.65 0.06 <0.0001

SS 89 35 (39.3) 19 (21.4) 82.0 0.59 0.10 <0.0001

MCTD 36 21 (58.3) 16 (44.4) 86.1 0.73 0.16 <0.0001

SSc 52 37 (71.2) 25 (48.1) 69.2 0.39 0.12 0.001

APS 16 6 (37.5) 2 (12.5) 75.0 0.38 0.20 0.03

Controls 79 10 (12.7) 9 (11.4) 96.2 0.82 0.11 <0.0001

Total 961 402 (41.8) 303 (31.5) 85.5 0.69 0.03 <0.0001

Abbreviations: APS, antiphospholipid syndrome, DM/PM, dermatomyositis/polymyositis;

MCTD, mixed connective tissue disease; ML, mouse liver; RA, rheumatoid arthritis; SLE,

systemic lupus erythematosus; SS, Sjögren’s syndrome; SSc, systemic sclerosis.

Supplementary Table 3a. Univariable analysis of predictors of ANA positivity using HEp2

ANA IFA. Reported as odds ratios (OR) and * if p<0.05.

Anti- Anti- Disease Age Female White Ant-dsDNA Anti-RNP Anti-Sm La/SS-B Ro/SS-A SLE1 0.97 1.15 0.26 2.95 1.07 3.00 3.20 1.85

DM/PM 1.03 2.50 3.00 RA 1.02 1.52 2.26* SS 1.02 1.96 1.33 MCTD 0.98 0.53 1.36 SSc 1.01 - 2.40 APS 0.87 4.50 - Controls 0.97 0.60 3.28 Abbreviations: APS, antiphospholipid syndrome, DM/PM, dermatopolymyositis; MCTD, mixed connective tissue disease; RA, rheumatoid arthritis; SLE, systemic lupus erythematosus; SS, Sjögren’s syndrome; SSc, systemic sclerosis; -, collinear variable.

Supplementary Table 3b. Multivariable analysis of predictors of ANA positivity using

HEp2 ANA IFA. Reported as odds ratios (OR) and * if p<0.05.

Anti- Anti- Disease Age Female White Ant-dsDNA Anti-RNP Anti-Sm La/SS-B Ro/SS-A SLE 0.98 1.08 0.38 2.01 0.63 1.45 1.49 2.19

DM/PM 1.05 2.60 2.25 RA 1.02 1.72 2.20* SS 1.03 2.71 1.28 MCTD 0.97 0.45 1.71 SSc 0.98 - 2.65 APS 0.88 2.02 - Control s 0.96 0.66 4.67 Abbreviations: APS, antiphospholipid syndrome, DM/PM, dermatopolymyositis; MCTD, mixed connective tissue disease; RA, rheumatoid arthritis; SLE, systemic lupus erythematosus; SS, Sjögren’s syndrome; SSc, systemic sclerosis; -, not included in multivariable analysis as collinear variable.

Supplementary Table 4a. Univariable analysis of predictors of ANA positivity using mouse

liver ANA IFA. Reported as odds ratios (OR) and * if p<0.05, ** p<0.01

Ant- Anti- Anti- Disease Age Female White Anti-RNP Anti-Sm dsDNA La/SS-B Ro/SS-A SLE 0.98 0.60 0.73 - 2.78* 4.43** 9.71* 2.48*

DM/PM 1.03 1.33 1.40 RA 1.01 1.72 1.26 SS 1.01 0.63 0.67 MCTD 1.02 1.21 0.96 SSc 1.02 0.51 0.80 APS 0.91 2.33 - Controls 1.00 2.13 2.05 Abbreviations: APS, antiphospholipid syndrome, DM/PM, dermatopolymyositis; MCTD, mixed connective tissue disease; RA, rheumatoid arthritis; SLE, systemic lupus erythematosus; SS, Sjögren’s syndrome; SSc, systemic sclerosis; -, collinear variable.

Supplementary Table 4b. Multivariable analysis of predictors of ANA positivity using

mouse liver ANA IFA. Reported as odds ratios (OR) and * if p<0.05.

Ant- Anti- Anti- Disease Age Female White Anti-RNP Anti-Sm dsDNA La/SS-B Ro/SS-A SLE 0.98 0.60 1.23 - 1.93 2.58 5.09 2.00

DM/PM 1.05 0.98 0.86 RA 1.01 1.91 1.49 SS 1.02 0.82 0.67 MCTD 1.02 1.10 0.84 SSc 1.02 0.41 0.74 APS 0.91 1.12 - Controls 0.99 3.75 2.32 Abbreviations: APS, antiphospholipid syndrome, DM/PM, dermatopolymyositis; MCTD, mixed connective tissue disease; RA, rheumatoid arthritis; SLE, systemic lupus erythematosus; SS, Sjögren’s syndrome; SSc, systemic sclerosis; -, not included in multivariable analysis as collinear variable.

Supplementary Table 5a. Univariable analysis of predictors of ANA agreement. Reported

as odds ratios (OR) and * if p<0.05, ** p<0.01

Anti- Anti- Disease Age Female White Ant-dsDNA Anti-RNP Anti-Sm La/SS-B Ro/SS-A SLE1 0.97* 1.22 0.59 8.75** 2.58 2.5* 4.33* 2.01* DM/PM 1.00 - - RA 1.00 1.04 0.55 SS 1.01 - 1.04 MCTD 0.97 0.86 - SSc 1.02 0.90 0.45 APS 1.04 - - Controls 1.00 1.68 - Abbreviations: APS, antiphospholipid syndrome, DM/PM, dermatopolymyositis; MCTD, mixed connective tissue disease; RA, rheumatoid arthritis; SLE, systemic lupus erythematosus; SS, Sjögren’s syndrome; SSc, systemic sclerosis; -, collinear variable.

Supplementary Table 5b. Multivariable analysis of predictors of ANA agreement.

Reported as odds ratios (OR) and * if p<0.05.

Anti- Anti- Disease Age Female White Ant-dsDNA Anti-RNP Anti-Sm La/SS-B Ro/SS-A SLE 0.97 1.35 0/87 6.27* 1.62 1.25 2.12 1.28

DM/PM 1.03 - - RA 1.00 1.07 0.54 SS 1.02 - 0.67 MCTD 1.02 1.22 - SSc 1.02 0.61 0.40 APS 1.02 - - Controls 1.01 2.19 - Abbreviations: APS, antiphospholipid syndrome, DM/PM, dermatopolymyositis; MCTD, mixed connective tissue disease; RA, rheumatoid arthritis; SLE, systemic lupus erythematosus; SS, Sjögren’s syndrome; SSc, systemic sclerosis; -, not included in multivariable analysis as collinear variable.

Choi MY, et al. Lupus Sci Med 2020; 7:e000431. doi: 10.1136/lupus-2020-000431