Validation of the 2019 ACR/EULAR classification criteria of systemic lupus erythematosus in 100 Japanese patients: a real-world setting analysis

The objective of the study is to evaluate the sensitivity of the new criteria for the classification of systemic lupus erythematosus (SLE), when applied to real SLE cases. We retrospectively reviewed the electronic medical records of 100 consecutive patients who visited St. Luke's International Hospital. Patients were included if they were clinically diagnosed as having SLE and excluded if they had other autoimmune disease or if they were less than 18 years old. Each patient was evaluated if they satisfied the American College of Rheumatology (ACR) 1997 classification criteria (1997 criteria), 2012 Systemic Lupus International Collaborating Clinics criteria (2012 criteria), or 2019 ACR/European League Against Rheumatism (EULAR) criteria. Among the 100 patients, the sensitivity of the 1997, 2012, and 2019 criteria was, 97, 99, and 92%, respectively. The total patient score with the 2019 criteria ranged from 12 to 44 (mean, 27.3). All patients who were classified as non-SLE with the 2019 criteria had an anti-nuclear antibody (ANA) titre of < 1:80. The 2019 criteria for SLE accomplished modestly high sensitivity in the real-world practice, but not as high as the 1997 and 2012 criteria. They possibly misclassify the real SLE cases as non-SLE, especially if patients have a low titre (< 1:80) of ANA.