Assessing the EULAR/ACR classification criteria for patients with systemic lupus erythematosus.

Overall, external validation supports the concepts and performance of the new SLE criteria. Variation in specificity in part appears to be related to incomplete application of the attribution rule of the criteria, under which items should only be counted for SLE if there were no more likely alternative explanation. Scientific uncertainty, and a lack of worldwide consensus, on the borderline between disease entities, e.g. between SLE and isolated cutaneous lupus erythematosus (CLE), also affected variation in estimates. For sensitivity, the performance of tests for ANA is critical.