Table 2.

Classification of statin-related myotoxic phenotypes (modified from Alfirevic et al., https://doi.org/10.1038/clpt.2014.121, [60]).

SRM Classification	Phenotype	Definition
SRM 0	Asymptomatic	Elevations of <4× upper normal limit in serum creatine kinase (CK)
SRM 1	Myalgia, tolerable	Muscle aches, cramps and/or weakness with no elevation of CK
SRM 2	Myalgia, intolerable	Muscle aches, cramps and/or weakness with < 4× upper normal limit of CK
SRM 3	Myopathy	CK levels > 4× but < 10× upper normal limit of CK
SRM 4	Severe myopathy	CK levels >10× but < 50× upper normal limit
SRM 5	Rhabdomyolysis	Either CK > 10× upper normal limit, muscle symptoms and renal impairment, or CK > 50× upper normal limit
SRM 6	Autoimmune-mediated, necrotizing myositis	HMGCR antibodies, HMGCR expression in muscle biopsy, incomplete resolution after statin discontinuation

CK, creatine kinase; HMGCR, 3-hydroxy-3-methylglutaryl-coenzyme A reductase; SRM, statin-related myotoxicity.