Table 4 Univariable comparison of demographics, disease subtypes and serological profiles in patients with persistent normocomplementaemia and those with at least one episode of hypocomplementaemia

Age at diagnosis, years

46.4 ± 0.5

44.6 ± 0.8

0.071

 Male

113 (13.1 %)

35 (12.7 %)

0.89

 Female

752 (86.9 %)

240 (87.3 %)

0.89

Disease duration

11.3 ± 0.4

11.6 ± 0.7

0.71

  ≤ 2 years

117 (14.5 %)

46 (17.5 %)

0.24

  ≤ 5 years

268 (33.2 %)

88 (33.5 %)

0.94

 Diffuse

238 (27.5 %)

72 (26.2 %)

0.67

 Limited

627 (72.5 %)

203 (73.8 %)

0.67

Overlap features present^a

186 (21.5 %)

81 (29.5 %)

0.007

 Rheumatoid arthritis

15 (1.7 %)

7 (2.6 %)

0.39

 Polymyositis

1 (0.1 %)

5 (1.8 %)

0.001

 Dermatomyositis

0 (0 %)

1 (0.4 %)

0.076

 Sjögren’s syndrome

14 (1.6 %)

7 (2.6 %)

0.32

 SLE

6 (0.7 %)

3 (1.1 %)

0.52

 Anti-centromere ANA

391 (46.0 %)

126 (47.0 %)

0.084

 Anti-Scl-70 antibodies

134 (16.1 %)

33 (12.3 %)

0.13

 Anti-Jo-1 antibodies

4 (0.5 %)

1 (0.4 %)

0.82

 Anti-RNP antibodies

10 (1.2 %)

12 (4.5 %)

0.001

 Anti-Ro antibodies

43 (5.2 %)

29 (10.8 %)

0.001

 Anti-La antibodies

12 (1.5 %)

6 (2.2 %)

0.38

 Anti-Sm antibodies

2 (0.2 %)

4 (1.5 %)

0.016

 Anti-PM-Scl antibodies

10 (1.2 %)

5 (1.9 %)

0.43

 Anti-dsDNA antibodies

16 (2.5 %)

10 (4.9 %)

0.089

 Anti-RNAP antibodies

61 (13.6 %)

23 (12.6 %)

0.74

ANCA

95 (12.1 %)

39 (15.2 %)

0.20

  MPO specificity

14 (1.8 %)

3 (1.2 %)

0.50

  PR-3 specificity

14 (1.8 %)

8 (3.1 %)

0.20

 Rheumatoid factor

208 (26.1 %)

80 (31.3 %)

0.11

 Anti-phospholipid antibodies

192 (24.0 %)

80 (31.3 %)

0.02

  Cardiolipin IgM

115 (63.2 %)

50 (69.4 %)

0.351

  Cardiolipin IgG

78 (41.5 %)

27 (34.2 %)

0.26

 β₂-glycoprotein

59 (32.8 %)

25 (33.3 %)

0.93

 Lupus anti-coagulant

15 (2.4 %)

11 (5.0 %)

0.056