External validation of EULAR/ACR classification criteria for idiopathic inflammatory myopathies

We have read with great interest the article published by Jinnin et al , which was an external validation of sensitivity and specificity of the EULAR/ACR (European League Against Rheumatism / American College of Rheumatology) classification criteria for idiopathic inflammatory myopathies with a Japanese cohort. The title and article claim that this is the first external validation study. While this may be true for a Japanese cohort, our intention is to alert the readers to the earlier published validation studies that preceded this and help highlight the complete body of evidence that should be considered. The idiopathic inflammatory myopathies (IIMs) are a group of uncommon disorders with a potential for significant mortality and morbidity. Progress in the understanding and management of these disorders has been …