Table 1

Patient characteristics

Patient characteristicsAdult DM
(n=21)
Juvenile DM
(n=17)
AS
(n=19)
IMNM
(adult +juvenile)
(n=8)
IBM
(n=9)
Control 1:
Overlap (adult +juvenile)
(n=22)
Control 2:
SLE
(n=30)
Control 3:
Healthy individuals
(n=19)
Female, n (%)10 (47.6)9 (53)10 (52.6)3 (37.5)6 (66.6)20 (90.9)26 (86.67)10 (52.63)
Age at diagnosis, years, mean (range)52.3 (20–84)9 (2–16)53.3 (17–77)56.9 (6–86)67 (52–79)39.5 (10–77)41.7 (19–70)ND (18–62)
Time since first diagnosis*, n (%)
 <3 months10 (47.6)7 (41.2)6 (31.6)4 (50)08 (36.4)14 (46.7)NA
 3–12 months3 (14.3)2 (11.8)5 (26.3)2 (25)1 (11)3 (13.7)3 (10)NA
 >12 months8 (38)8 (47.1)8 (42.1)2 (25)8 (89)11 (50)13 (43.3)NA
SIGLEC1 expression, mAb/cell, median (IQR)*5876 (1211–10282)5272 (1200–12691)1580 (1200–3390)1246 (1200–1853)1949 (1306–4602)1661 (1200–6915)7947 (3695–11924)1200 (1200–1200)
CK, U/l, median (IQR)*109 (74.5–442.5), NR=1218.5 (116.3–1988), NR=1627 (102.3–2173), NR=12118 (445.8–4353)497 (322.5–988.5), NR=1421 (68–962.3), NR=462.5 (45.4–97.3)ND
CRP, mg/L, median (IQR)*4.95 (0.7–24), NR=10.8 (0.3–3.3), NR=25.5 (1.9–29.1), NR=12.75 (0.68–11.3), NR=23.3 (1.3–33), NR=13.0 (0.9–7.4), NR=22.4 (0.7–17.3)ND
Biopsy-confirmed IIM diagnosis/performed biopsies14/156/77/96/79/90/10NANA
Definite’ or ‘probable’ IIM as per EULAR/ACR criteria, n (%)19 (90.5)13 (82.4)17 (89.5)5 (62.6)9 (100%)NANANA
PGA, mean (range)*6 (2–10)4.4 (0–8)5.4 (2–9)4.9 (2–8)4.22 (3-6)4.5 (3–9), NR=7NANA
CMAS, mean (range)†NA35 (2–52), NR=4NANANANANANA
SLEDAI-2k, mean (range)*NANANANANANA6.6 (0–24)NA
Prednisolone, no of patients (mean in mg/day on visit 1)12 (36.1 mg/day)9 (8.3 mg/day), NR=116 (13.3 mg/day)4 (13.1 mg/day)3 (7.5 mg/day)9 (6.9 mg/day), NR=117 (NR)NA
Other medication*, n (%)
 Hydroxychloroquine/chloroquine1 (4.8)2 (11.8)3 (15.8)3 (13.7)10 (33.3)NA
 Intravenous immunoglobulin2 (9.5)2 (11.8)1 (5.3)1 (12.5)1 (11.1)NA
 Methotrexate1 (4.8)6 (35.3)3 (15.8)1 (12.5)1 (11.1)4 (18.2)1 (3.3)NA
 Rituximab2 (10.5)1 (11.1)NA
 JAK Inhibitor3 (14.3)NA
 MMF/CsA/Cyc/AZA5 (23.8)3 (17.6)5 (26.3)2 (25)3 (13.7)6 (20)NA
 No medication8 (38.1)7 (41.2)3 (15.8)4 (50)5 (55.6)10 (45.5)13 (43.3)19 (100)
  • *On first visit with assessment of SIGLEC1.

  • †On first visit with assessment of SIGLEC1 and CMAS.

  • ACR, American College of Rheumatology; AS, antisynthetase syndrome; AZA, azathioprine; CK, creatine kinase; CMAS, Childhood Myositis Assessment Scale; CRP, C reactive protein; CsA, ciclosporin A; Cyc, cyclophosphamide; DM, dermatomyositis; IBM, inclusion body myositis; IIM, idiopathic inflammatory myopathies; IMNM, immune-mediated necrotising myopathy; JAK, Janus Kinase; Mab, monoclonal antibody; MCTD, mixed connective tissue disease; MMF, mycophenolate mofetil; n, absolute value; NA, not applicable; ND, not determined; NR, not reported; PGA, physician global assessment; SIGLEC1, sialic acid binding Ig-like lectin 1; SLE, systemic lupus erythematosus; SLEDAI-2k, Systemic Lupus Erythematosus Disease Activity Index 2000.