Table 1.
Demographic data and baseline characteristics of patients and controls.
| IIM (n = 37) |
p-Value | SSc (n = 17) |
p-Value | RA (n = 10) |
p-Value | HC (n = 7) |
|
|---|---|---|---|---|---|---|---|
| Female, n (%) | 26 (71.3) |
0.41 | 16 (94.1) |
0.52 | 8 (80) |
0.78 | 6 (85.7) |
| Age, years (range) |
59.0 (51.0–71.0) |
0.75 | 70.0 (55.0–75.0) |
0.13 | 69.0 (55.5–76.8) |
0.16 | 57 (56.5–60.0) |
| Disease duration, months (range) |
16 (7–84) |
60 (34–288) |
53 (14–177) |
- | |||
| Untreated, n (%) | 14 (37.8) |
6 (35.3) |
0 (0) |
- | |||
| ILD, n (%) | 27 (72.9) |
10 (58.8) |
3 (30) |
- | |||
| CK, mean (S.D.), U/L | 1520 (3955) |
n.d. | n.d. | n.d. | |||
| KL-6, U/mL (range) |
506 (289–687) |
533 (371–1144) |
271 (212–372) |
n.d. | |||
| %VC, % (range) |
79.6 (65.1–96.8) |
76.7 (67.0–84.5) |
100.9 (77.5–132.6) |
n.d. | |||
| %DLCO, % (range) |
74.7 (64.3–90.8) |
80.4 (71.0–93.1) |
82.4 (72.6–92.2) |
n.d. | |||
| IIM (n = 37) |
N (%) |
SSc (n = 17) |
N (%) |
RA (n = 10) |
N (%) |
||
| Autoantibody profile, n (%) | ARS | 14 (37.8) | Scl-70 | 6 (35.3) | RF | 9 (90) | |
| Jo-1 | 5 (13.5) | Centromere | 9 (52.9) | ACPA | 9 (90) | ||
| PL-7 | 3 (8.1) | RNA polymerase III | 2 (11.8) | ||||
| PL-12 | 1 (2.7) | ||||||
| EJ | 2 (5.4) | ||||||
| Unknown | 3 (8.1) | ||||||
| MDA-5 | 9 (24.3) | ||||||
| TIF-1γ | 1 (2.7) | ||||||
| Mi-2 | 3 (8.1) | ||||||
| SRP | 1 (2.7) | ||||||
| HMG-CR | 1 (2.7) | ||||||
| M2 | 2 (5.4) | ||||||
| Negative | 6 (16.2) | ||||||
Data are reported as median (IQR) unless stated otherwise. n.d.: no data. p values were calculated using Fisher’s exact test to assess the proportion of females, and unpaired t tests were used to assess differences in age between healthy controls and patients in each disease group. Disease duration was defined as the duration from the diagnosis of IIM to the serum sample collection. IIM: idiopathic inflammatory myopathy; SSc: systemic sclerosis; RA: rheumatoid arthritis; HC: healthy controls; ILD: interstitial lung disease; CK: creatine kinase; KL-6: Sialylated carbohydrate antigen Krebs von den Lungen-6; VC: vital capacity; DLCO: carbon monoxide diffusing capacity; ARS; aminoacyl-tRNA synthetases; MDA5: melanoma differentiation-associated gene 5 protein; TIF1-ɤ: transcriptional intermediary factor 1ɤ; SRP: signal recognition particle; HMGCR: 3-hydroxy-3-methyl coenzyme A reductase protein; M2: mitochondrial M2; RF: rheumatoid factor; ACPA: anti-cyclic citrullinated peptide antibody; IQR: interquartile range.