I12 EULAR/ACR SLE classification criteria: 5 years later

Objective To review lessons learned since the 2019 publication of the European League Against Rheumatism/American College of Rheumatology (EULAR/ACR) classification criteria for systemic lupus erythematosus (SLE). Methods A literature review was performed for manuscripts in English language on the EULAR/ACR criteria for SLE, which were published since the publication of the criteria. Results A total of 28 different studies worldwide externally validated the EULAR/ACR criteria since their publication. These included 8,800 patients with SLE and 5,492 patients with other diseases. Cohorts differed, and included pediatric SLE and early disease (table 1). In the combined SLE population, data on anti-nuclear antibodies (ANA) could be analyzed for 7,393 patients, and 97,2% (7,185/7,393) had positive ANA. The EULAR/ACR criteria had a combined sensitivity of 93.3% (8,207/8,800) and a specificity of 93.7% (5,143/5,492). These data are close to the validation cohort data of the EULAR/ACR criteria with a sensitivity of 96.1% and a specificity of 93.4%. The slightly lower sensitivity in early SLE cohorts is in line with data from the EULAR/ACR criteria cohort, showing a sensitivity of 89% in the first year, increasing to 97% for years 1 to 3. The percentage of ANA positive patients and EULAR/ACR classification criteria sensitivity were significantly correlated (Spearman r=0.52, p=0.0041). EULAR/ACR criteria specificity relies on correctly applying their attribution rule, that items must not be attributed to SLE if there is a more likely alternative diagnosis. In Chung et al, specificity increased from 85.8% to 95.0% when attribution was correctly done. Data from the EULAR/ACR cohort show that this may be particularly relevant for lupus arthritis, were the misattribution of rheumatoid arthritis would have significant impact. Conclusions The EULAR/ACR classification criteria have been extensively validated by groups worldwide, and the data support both their performance and their structure with ANA as an obligatory entry criterion. Acknowledgements The development of the SLE classification criteria was jointly supported by EULAR and the ACR.