. 2015 Jan 13;129(5):611–624. doi: 10.1007/s00401-015-1384-5

Table 1.

The ENMC IBM Research Diagnostic Criteria 2011 [83]

Clinical and laboratory features	Classification	Pathological features
Duration >12 months	Clinico-pathologically defined IBM	All of the following:
Age at onset >45 years		Endomysial inflammatory infiltrate
Age at onset >45 years		Rimmed vacuoles
Knee extension weakness ≥hip flexion weakness and/or finger flexion weakness >should abduction weakness		Protein accumulation^a or 15–18 nm filaments
CK no greater than 15 × ULN		Protein accumulation^a or 15–18 nm filaments
Duration >12 months	Clinically defined IBM	One or more, but not all, of:
Age at onset >45 years		Endomysial inflammatory infiltrate
Knee extension weakness ≥hip flexion weakness and finger flexion weakness >should abduction weakness		Up-regulation of MHC-I
		Rimmed vacuoles
		Protein accumulation^a or 15–18 nm filaments
CK no greater than 15 × ULN		Protein accumulation^a or 15–18 nm filaments
Duration >12 months	Probable IBM	One or more, but not all, of:
Age at onset >45 years		Endomysial inflammatory infiltrate
Knee extension weakness ≥hip flexion weakness or finger flexion weakness >should abduction weakness		Up-regulation of MHC-I
		Rimmed vacuoles
		Protein accumulation^a or 15–18 nm filaments
CK no greater than 15 × ULN		Protein accumulation^a or 15–18 nm filaments

^aDemonstration of amyloid or other protein accumulation by established methods (e.g. for amyloid Congo red, crystal violet, thioflavin T/S, for other proteins p62, SMI-31, TDP-43). Current evidence favours p62 in terms of sensitivity and specificity but the literature is limited and further work required