Table 1 Clinical and laboratory characteristics between different of subgroups of patients

Age of onset (years)

54 (49, 60)

24 (19, 37)

23.1 ± 9.8

< 0.0001

< 0.0001

0.190

Age of visit (years)

55 (49, 61)

33.6 ± 13.2

29.4 ± 13.7

< 0.0001

< 0.0001

0.297

Disease duration (months)*

4 (2, 12)

36 (20, 89)

36 (24, 102)

< 0.0001

< 0.0001

0.657

Sex, female (n, %)

48, 66.2%

14, 58.3%

12, 54.5%

0.623

0.326

> 0.9999

Cervical extensor

weakness (n, %)

21, 29.6%

1, 4.2%

2, 9.5%

0.011

0.086

0.592

Cervical flexor

weakness (n, %)

31, 43.7%

1, 4.2%

1, 4.8%

0.0003

0.0006

> 0.9999

Myalgia (n, %)

14, 19.7%

2, 8.3%

3, 13.6%

0.343

0.753

0.652

Bulbar symptoms (n, %)

10, 14.1%

0

0

0.061

0.109

—

Distal weakness (n, %)

31, 43.7%

9, 37.5%

9, 42.9%

0.640

> 0.9999

0.767

CK (U/L)

3470 (1869, 7613)

6921 (3605, 10266)

3247 (1727, 5043)

0.022

0.375

0.002

Synchronous Mb (ng/ml)

982 (729, 1566) (n = 20)

335 (191, 773) (n = 8)

315 (241, 395) (n = 7)

0.016

0.0004

0.694

Ratio of Mb to CK

0.264 (0.207, 0.384)

0.113 ± 0.040

0.116 ± 0.038

< 0.0001

< 0.0001

0.884