Patient characteristics | Adult 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 months | 10 (47.6) | 7 (41.2) | 6 (31.6) | 4 (50) | 0 | 8 (36.4) | 14 (46.7) | NA |
3–12 months | 3 (14.3) | 2 (11.8) | 5 (26.3) | 2 (25) | 1 (11) | 3 (13.7) | 3 (10) | NA |
>12 months | 8 (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=1 | 218.5 (116.3–1988), NR=1 | 627 (102.3–2173), NR=1 | 2118 (445.8–4353) | 497 (322.5–988.5), NR=1 | 421 (68–962.3), NR=4 | 62.5 (45.4–97.3) | ND |
CRP, mg/L, median (IQR)* | 4.95 (0.7–24), NR=1 | 0.8 (0.3–3.3), NR=2 | 5.5 (1.9–29.1), NR=1 | 2.75 (0.68–11.3), NR=2 | 3.3 (1.3–33), NR=1 | 3.0 (0.9–7.4), NR=2 | 2.4 (0.7–17.3) | ND |
Biopsy-confirmed IIM diagnosis/performed biopsies | 14/15 | 6/7 | 7/9 | 6/7 | 9/9 | 0/10 | NA | NA |
‘Definite’ or ‘probable’ IIM as per EULAR/ACR criteria, n (%) | 19 (90.5) | 13 (82.4) | 17 (89.5) | 5 (62.6) | 9 (100%) | NA | NA | NA |
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=7 | NA | NA |
CMAS, mean (range)† | NA | 35 (2–52), NR=4 | NA | NA | NA | NA | NA | NA |
SLEDAI-2k, mean (range)* | NA | NA | NA | NA | NA | NA | 6.6 (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=1 | 16 (13.3 mg/day) | 4 (13.1 mg/day) | 3 (7.5 mg/day) | 9 (6.9 mg/day), NR=1 | 17 (NR) | NA |
Other medication*, n (%) | ||||||||
Hydroxychloroquine/chloroquine | 1 (4.8) | 2 (11.8) | 3 (15.8) | – | – | 3 (13.7) | 10 (33.3) | NA |
Intravenous immunoglobulin | 2 (9.5) | 2 (11.8) | 1 (5.3) | 1 (12.5) | 1 (11.1) | – | – | NA |
Methotrexate | 1 (4.8) | 6 (35.3) | 3 (15.8) | 1 (12.5) | 1 (11.1) | 4 (18.2) | 1 (3.3) | NA |
Rituximab | – | – | 2 (10.5) | – | 1 (11.1) | – | – | NA |
JAK Inhibitor | 3 (14.3) | – | – | – | – | – | – | NA |
MMF/CsA/Cyc/AZA | 5 (23.8) | 3 (17.6) | 5 (26.3) | 2 (25) | – | 3 (13.7) | 6 (20) | NA |
No medication | 8 (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.