Table 2 Presence of perifascicular atrophy and RIG-I staining in the muscle biopsies of patients with DM and non-DM (1) and sensitivity and specificity of atrophy and RIG-I positivity to diagnose DM (2)

PFA^{#, a}

PFA (2 rows)^b

RIG-I^c

 DM (N; %)

16 (36%)

11 (25%)

22 (50%)

 No DM (N; %)

13 (21%)

5 (8%)

7 (11%)

 p*

0.09

0.02

<0.001

p (a vs b)^**

p (a vs c)^**

p (b vs c)^**

 Sensitivity

36%

25%

50%

0.06

0.08

0.005

 Specificity

79%

92%

88%

<0.01

0.08

0.7

 Reproducibility (κ)^***

0.37

0.51