Table 4.

Performance of the EULAR/ACR classification criteria for idiopathic inflammatory myopathies (IIM) and existing classification and diagnostic criteria for IIM

PERFORMANCE (%)	The EULAR/ACR classification criteria for IIM^*		Bohan and Peter^† [7, 8]	Tanimoto et al. [10]	Targoff et al.^† [11]	Dalakas and Hohlfeld^† [14]	ENMC Hoogendijk et al.^† [15]
PERFORMANCE (%)	Without muscle biopsy	With muscle biopsy	Bohan and Peter^† [7, 8]	Tanimoto et al. [10]	Targoff et al.^† [11]	Dalakas and Hohlfeld^† [14]	ENMC Hoogendijk et al.^† [15]

Mean (95% CI)
Sensitivity	87 (84–90)	93 (89–95)	98 (96–99)	96 (94–97)	93 (90–95)	6 (5–8)	52 (48–55)
Specificity	82 (77–87)	88 (83–93)	55 (50–61)	31 (25–37)	89 (84–92)	99 (98–100)	97 (95–98)

Mean
Positive predictive value	90	94	85	80	95	92	96
Negative predictive value	79	85	90	73	85	43	57
Correctly classified	86	91	86	79	91	45	70

CORRECT CLASSIFICATION OF IIM PER SUBGROUP^‡ (%)

Amyopathic dermatomyositis	94	60	25	14	0	0	0
Dermatomyositis	96	98	100	96	99	7	83
Hypomyopathic dermatomyositis	83	100	80	40	67	0	20
Immune-mediated necrotizing myopathy	100	100	100	100	100	0	10
Inclusion body myositis	58	94	97	97	91	1	1
Juvenile dermatomyositis	97	96	100	96	98	5	86
Polymyositis	79	86	95	100	85	11	9

Cutoff for probability: 55%

^†

Definite and probable polymyositis and dermatomyositis

^‡

Classification as idiopathic inflammatory myopathy per subgroup out of total number of cases per subgroup, expressed as mean

IIM, idiopathic inflammatory myopathies; ENMC, European Neuromuscular Centre; CI, confidence interval