IFIH1 and clinically amyopathic dermatomyositis: RP-ILD was more frequent in patients with CADM, both in the anti-MDA5 positive group (7 of 8 CADM versus 1 of 6 DM; P < 0.05) and in the overall cohort (8 of 15 CADM patients versus 3 of 102 DM patients; P < 0.05).