Table 1

Myositis-specific and myositis-associated antibodies in 144 patients with myositis and in 240 controls

SLE (n=40)IIM versus contr
# Pos% Pos# Conc pos>3 × cut-off# Pos% Pos# Conc pos# Pos# Pos# Pos# Pos# Pos# PosLR95% CIP value
Jo-1 Alphadia3121.422/25/223010.41/1/100010053.59.1 to 298<0.0001
Jo-1 EuroImmun2920.0222472.910011236.93.2 to 15.1<0.0001
Jo-1 Trinity2416.662.51201206.62.9 to 15.6<0.0001
PL-7 Alphadia10.70/1/0100.00/0/00000000.44 to ∞0.3750
PL-7 EuroImmun32.11120.800000112.60.50 to 12.40.3680
PL-7 Trinity10.720.80100100.90.11 to 6.31.0000
PL-12 Alphadia32.11/2/1210.40/0/10100005.30.72 to 34.70.1504
PL-12 EuroImmun32.11231.300100111.60.39 to 7.10.6758
PL-12 Trinity32.172.92201200.70.20 to 2.50.7492
EJ Alphadia32.12/2/2200.00/0/00000001.3 to ∞0.0520
EJ EuroImmun21.42100.000000000.87 to ∞0.1400
EJ Trinity21.420.80100011.80.30 to 9.40.6326
SRP Alphadia32.11/3/1100.00/0/00000001.3 to ∞0.0520
SRP EuroImmun42.81341.702100101.60.46 to 6.00.4799
SRP Trinity21.420.80100101.80.30 to 9.40.6326
Mi-2 Alphadia85.56/7/6700.00/0/00000003.5 to ∞0.0003
Mi-2a EuroImmun85.57231.310000034.21.3 to 15.30.0231
Mi-2b EuroImmun74.8110.400000112.01.9 to 72.30.0052
Mi-2 Trinity96.210.400000115.52.5 to 91.10.0008
MDA-5 Alphadia74.84/7/4600.00/0/00000003.1 to ∞0.0010
MDA-5 EuroImmun106.95700.000000004.4 to ∞<0.0001
MDA-5 Trinity106.952.10110033.31.2 to 9.20.0267
TIF1γ Alphadia32.13/3/3220.80/0/00002002.60.50 to 12.40.3680
TIF1γ EuroImmun1812.48631.301010019.53.0 to 29.8<0.0001
TIF1 (γ+α) Trinity1611.0229.23212681.20.66 to 2.20.5974
HMGCR Alphadia74.8700.00000003.1 to ∞0.0010
Ro52 Alphadia3222.126/29/26275723.853/57/53001336170.90.61 to 1.30.6160
Ro52 EuroImmun3926.933337932.9700621238210.80.58 to 1.10.1785
Ro52 Trinity3624.88937.12931639200.70.47 to 0.910.0095
SAE1/SAE2 Alphadia53.42/3/3331.30/0/01001102.60.74 to 10.40.1572
SAE1 EuroImmun42.82200.000000001.8 to ∞0.0193
SAE1 Trinity64.131.30020103.20.93 to 12.00.0854
NXP-2 Alphadia85.53/4/5510.40/1/000001013.82.2 to 81.70.0021
NXP-2 EuroImmun53.43431.300110102.60.74 to 10.40.1572
MORC3 Trinity74.820.81000106.01.4 to 24.50.0297
OJ EuroImmun00.00000.00000000
OJ Trinity00.000.0000000
PM75 EuroImmun74.841135.452006320.90.38 to 2.11.0000
Pm-Scl75 Trinity74.8166.73314320.70.31 to 1.70.5148
PM100 EuroImmun74.85083.350303111.50.56 to 3.80.5875
PM-Scl100 Trinity117.6177.13515211.10.53 to 2.20.8416
Ku EuroImmun42.83362.540111031.10.34 to 3.61.0000
Ku Trinity32.152.10201021.00.27 to 3.71.0000
U1 snRNP 68 Trinity10.741.70001030.40.06 to 2.70.6544
U1 snRNP A Trinity32.1114.60012080.50.14 to 1.50.2672
U1 snRNP C Trinity53.4145.81021190.60.23 to 1.50.3424
U2 snRNP A′ Trinity21.441.70030100.80.18 to 3.81.0000
U2 snRNP B″ Trinity21.462.50050100.60.13 to 2.40.7154
Fibrillarin Trinity10.700.00000000.44 to ∞0.3750
KS Trinity32.110.40000105.30.72 to 34.70.1504
CN-1A Trinity1913.12510.40334871.30.73 to 2.20.4080
  • For each antibody, the number of positive samples (and percentage) is given for myositis patients and controls as well as the number of positive samples with a value higher than 3 times the cut-off (for patients with myositis). The number of concordant (conc) results is given as follows: on the line that describes the Alphadia results, concordance between all three assays (first number), between Alphadia and Euroimmun (second number) and between Alphadia and Trinity (third number) is given. On the line that describes the Euroimmun results, concordance between Euroimmun and Trinity is given. The likelihood ratio (LR) is given as well as the association between each of the antibodies and IIM (evaluated by χ2 testing or Fisher’s exact test (if cell size was <10) using Analyse-it for Excel). Patients with IIM (female/male: 80/64) (median age at diagnosis 53 years; age range 3–84 years) included dermatomyositis (n=57), polymyositis (n=48), antisynthetase syndrome (n=15), necrotising myositis (n=6), clinically amyopathic dermatomyositis (n=7), sporadic inclusion body myositis, overlap and undifferentiated myositis (n=9) and undefined (n=2). Diagnosis was based on a combination of clinically significant muscle weakness, elevated creatine kinase levels, electromyography, muscle biopsy (available in 90 of 144 patients) and/or skin manifestations. Demographic data (female/male, median age (age range)) of the controls were 149/91, 57 years (16–85 years); 17/23, 56 years (18–69 years) for the blood donors; 8/32, 56 years (32–75 years) for the chronic inflammatory demyelinating polyneurophathy (CIPD); 30/10, 57 years (26–75 years) for rheumatoid arthritis (RA); 25/15, 61 years (41–81 years) for systemic sclerosis (SSc); 35/5, 52 years (16–85 years) for Sjögren’s syndrome (SjS); and 34/6, 47 years (25–84 years) for systemic lupus erythematosus (SLE).

  • IIM, inflammatory myopathy.