Performance of the 2019 European League Against Rheumatism/American College of Rheumatology classification criteria for systemic lupus erythematosus in Asian patients: a single-centre retrospective cohort study in Korea

Objectives To evaluate the performance of the 2019 European League against Rheumatism/American College of Rheumatology (EULAR/ACR) classification criteria for systemic lupus erythematosus (SLE) in Asian patients. Methods We conducted an electronic medical chart review of patients with SLE and defined rheumatic diseases. Classification criteria of the 1997 ACR, 2012 Systemic Lupus International Collaborating Clinics (SLICC), and 2019 EULAR/ACR were examined based on sensitivity, specificity, positive predictive value, negative predicted value, and accuracy using clinical diagnosis as the gold standard. Results A total of 335 SLE patients and 337 non-SLE patients were analysed. Non-SLE patients included rheumatoid arthritis (RA) (n=92), anti-phospholipid syndrome (APS) (n=57), mixed connective tissue disease (n=52), systemic sclerosis (n=43), primary Sjogren's syndrome (SS) (n=39), undifferentiated connective tissue disease (n=28), RA with secondary SS (n=24), dermatomyositis (n=1), and spondyloarthropathy (n=1). The sensitivity was 97.6% (95% confidence interval (CI): 0.954-0.989) for the 2019 EULAR/ACR criteria, 98.5% (95% CI: 0.966-0.995) for the 2012 SLICC criteria and 95.5% (95% CI: 0.927-0.975) for the 1997 ACR criteria. The specificity was 91.4% (95% CI: 0.879-0.942) for the 2019 EULAR/ACR criteria, 92.6% (95% CI: 0.892-0.951) for the 2012 SLICC criteria 93.8% (95% CI: 0.906-0.961) for the 1997 ACR criteria. Conclusions The 2019 EULAR/ACR criteria for SLE had comparable performance to the 2012 SLICC criteria regarding diagnostic sensitivity and specificity in Korean population of SLE and other rheumatic diseases. However, the new criteria could not reach higher specificity than the 2012 SLICC criteria.