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)

1)
	PFA#, a	PFA (2 rows)b	RIG-Ic
DM (N; %)	16 (36%)	11 (25%)	22 (50%)
No DM (N; %)	13 (21%)	5 (8%)	7 (11%)
p*	0.09	0.02	<0.001
2)
				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

Healthy controls were excluded from this analysis. DM dermatomyositis, PFA perifascicular atrophy. ^#Perifascicular atrophy includes one or more rows of atrophic muscle fibers. ^*Association between bivariate variables was perfomed using Fisher’s exact test. ^**Sensitivity and specificity were compared using the McNemar test. ^***Reproducibility was assessed using Cohen’s kappa coefficient (κ).