Table 2

Extent of thigh MRI findings among clinical subsets

IMNMIBM (n=153)PM (n=176)DM (n=219)CADM (n=17)Total (n=666)
Total (n=101)HMGCR (n=50)SRP (n=22)
Mean (SD)Mean (SD)Mean (SD)Mean (SD)Mean (SD)Mean (SD)Mean (SD)Mean (SD)
Oedema55.5 (32.2)***58.9 (31.8)65.8 (28.9)48.1 (24.6)***29.4 (30.5)***30.1 (36.7)***6.1 (18.5)***37.3 (33.5)
Atrophy23.2 (28.7)**21.7 (28.9)*38.2 (30.2)*32.2 (26.7)***12.7 (24.6)*5.7 (16.7)***2.5 (7.4)*16.2 (25.5)
Fatty replacement38.0 (33.1)*34.4 (30.9)49.1 (31.2)50.1 (27.3)***28.3 (31.1)17.5 (27.0)***7.1 (12.8)**30.7 (31.6)
Fascial oedema6.2 (15.1)*5.1 (15.2)6.0 (12.2)6.0 (12.0)**5.8 (11.8)**16.5 (24.3)***8.6 (17.0)9.5 (18.1)
  • Mean percentage of each major clinical group (IMNM, IBM, PM, DM and CADM) compared with the rest of the sample using Student’s t-test. In separate analyses, patients with anti-HMGCR and anti-SRP were compared to each other only.

  • *<0.05; **<0.01; ***<0.001.

  • CADM, clinically amyopathic dermatomyositis; DM, dermatomyositis; HMGCR, HMG-CoA reductase; IBM, inclusion body myositis; IMNM, immune-mediated necrotising myopathy; PM, polymyositis; SRP, signal recognition particle.