The association of low complement with disease activity in systemic sclerosis: a prospective cohort study

Table 1 Patient characteristics (n = 1140)

Characteristic	n (%) or mean ± SD
Age at diagnosis, years	46.0 ± 14.1
Age at recruitment, years	57.4 ± 12.3
Follow-up duration, years	3.4 ± 1.7
Sex
Male	148 (13.0 %)
Female	992 (87.2 %)
Race
White	1012 (93.3 %)
Asian	50 (4.7 %)
Australian Aboriginal or Torres Strait Islander	14 (1.3 %)
Other	9 (0.9 %)
Disease duration at recruitment^a	11.3 ± 9.9
≤ 2 years	163 (14.3 %)
≤ 5 years	356 (31.2 %)
Disease subtype^b
Diffuse	310 (27.2 %)
Limited	830 (72.8 %)
Overlap disease features present ever^c	267 (23.4 %)
Rheumatoid arthritis	22 (1.9 %)
Polymyositis	6 (0.5 %)
Dermatomyositis	1 (0.01 %)
Sjögren’s syndrome	21 (1.8 %)
SLE	9 (0.8 %)
Serological profile at recruitment
Anti-centromere ANA	517 (46.2 %)
Anti-Scl-70 antibodies	167 (15.2 %)
Anti-RNAP antibodies	84 (13.3 %)
Anti-U1 RNP antibodies	22 (2.0 %)
Anti-Ro antibodies	72 (6.6 %)
Anti-La antibodies	18 (1.6 %)
Anti-Sm antibodies	6 (0.6 %)
Anti-PM-Scl antibodies	15 (1.4 %)
Anti-dsDNA antibodies	26 (3.1 %)
Anti-Jo-1 antibodies	5 (0.5 %)
ANCA	134 (12.9 %)
MPO specificity	17 (1.6 %)
PR-3 specificity	22 (2.1 %)
Rheumatoid factor	288 (27.2 %)
Anti-phospholipid antibodies	272 (25.7 %)
Cardiolipin IgM	165 (65.0 %)
Cardiolipin IgG	105 (39.3 %)
Anti-β₂-glycoprotein antibody	84 (33.0 %)
Lupus anticoagulant	26 (3.1 %)

Abbreviations: ANA Anti-nuclear antibody, Anti-Scl-70 Anti-scleroderma-70 antibodies, Anti-U1 RNP Anti-ribonucleoprotein antibodies, Anti-Sm Anti-Smith antibodies, Anti-PM-Scl Anti-polymyositis scleroderma antibodies, Anti-dsDNA Anti-double-stranded DNA antibodies, Anti-RNAP Anti-RNA polymerase antibodies, ANCA Anti-neutrophil cytoplasmic antibodies, MPO Myeloperoxidase, PR-3 Proteinase-3
^aSince onset of first non-Raynaud’s phenomenon disease manifestation
^bDisease subtype based on extent of skin involvement, with limited disease being confined to the extremities distal to elbows and knees, as well as the face
^cActual overlap disease features specified for only a proportion of patients classified by the treating physician as having ‘SSc overlap syndrome’

ISSN: 1478-6362