PT  - JOURNAL ARTICLE
AU  - Masatoshi Jinnin
AU  - Akiko Ohta
AU  - Shoichiro Ishihara
AU  - Hirofumi Amano
AU  - Tatsuya Atsumi
AU  - Manabu Fujimoto
AU  - Takashi Kanda
AU  - Yasushi Kawaguchi
AU  - Atsushi Kawakami
AU  - Akio Mimori
AU  - Tsuneyo Mimori
AU  - Toshihide Mimura
AU  - Yoshinao Muro
AU  - Hajime Sano
AU  - Jun Shimizu
AU  - Tsutomu Takeuchi
AU  - Yoshiya Tanaka
AU  - Kazuhiko Yamamoto
AU  - Takayuki Sumida
AU  - Hitoshi Kohsaka
ED  - ,
TI  - First external validation of sensitivity and specificity of the European League Against Rheumatism (EULAR)/American College of Rheumatology (ACR) classification criteria for idiopathic inflammatory myopathies with a Japanese cohort
AID  - 10.1136/annrheumdis-2019-215488
DP  - 2020 Mar 01
TA  - Annals of the Rheumatic Diseases
PG  - 387--392
VI  - 79
IP  - 3
4099  - http://ard.bmj.com/content/79/3/387.short
4100  - http://ard.bmj.com/content/79/3/387.full
SO  - Ann Rheum Dis2020 Mar 01; 79
AB  - Objective To externally validate the performance of the new European League Against Rheumatism (EULAR)/American College of Rheumatology (ACR) classification criteria set for idiopathic inflammatory myopathies (IIM) with a Japanese cohort.Methods This study included 420 IIM and 402 non-IIM cases. Probability of having IIM in each patient was calculated using the collected data set. The cut-off probability was set at 55%, as recommended by EULAR/ACR. Patients classified as IIM by the criteria were further subclassified with classification trees.Results When the probability cut-off was set at 55%, the sensitivity/specificity of the new criteria to diagnose IIM were 89.3%/91.0% in the total cohort, 88.1%/95.1% without muscle biopsy data and 90.4%/65.5% with biopsy data. The cohort included 12 overlap syndrome patients with biopsy data, who were included as non-IIM cases in accordance with traditional Japanese methods. When they were included in the IIM cases, the specificity in patients with biopsy increased to 74.4%. The sensitivity/specificity of the new criteria to diagnose polymyositis/dermatomyositis (PM/DM) plus juvenile and amyopathic DM in the Japanese cohort was 87.4%/92.4%, which were greater than those of the Tanimoto’s criteria revised to enable classification of amyopathic DM (ADM) (71.2%/87.8%) and were comparable with those of Bohan & Peter’s criteria to diagnose those diseases except for ADM (88.4%/88.3%).Conclusions Our study externally validated high specificity of the new criteria for the first time, although with several limitations, including low percentage of child patients. The new criteria have higher sensitivity and/or specificity in classification of PM/DM than the previously reported criteria, demonstrating its usefulness for interethnic patients.