EULAR/ACR classification criteria for SLE

Supported by both the European League Against Rheumatism (EULAR) and the American College of Rheumatology (ACR) from the beginning, a large transatlantic, and in many phases worldwide, project has led to new classification criteria for systemic lupus erythematosus (SLE). The project had ambitious goals, particularly maintaining the high specificity of the ACR criteria, while reaching a sensitivity close to the Systemic Lupus International Collaborating Clinics (SLICC) 2012 criteria. The validation data suggest that the new criteria reached this goal, with a specificity of 93% (as for the ACR criteria) and a sensitivity of 96% (vs 97% for the SLICC criteria). The new EULAR/ACR classification criteria use positive antinuclear antibodies (ANA) as an entry criterion and have weighted items, ranging from 2 (for delirium, non-infectious fever and anti-phospholipid antibodies) to 10 (for class III or IV lupus nephritis). The cut-off for classification is 10, reached by class III/IV nephritis alone. Items are organized in domains, within which only the highest item is to be counted. Instead of many defined exclusions, one rule is used for all, namely that items are to be attributed to SLE and counted only if there is no more likely alternative diagnosis. These criteria are now expected to be externally validated in various other cohorts. The team spirit and collegiality characteristic for this EULAR/ACR criteria effort will hopefully facilitate future international projects on SLE.