In this study, the aim is to develop and validate a new index, SLEDAI-2K Glucocorticosteroid Index (SLEDAI-2KG). It is very challenging to evaluate improvement in drug trials in the context of the standard of care treatment which includes corticosteroids. This novel index, SLEDAI-2KG, will help to overcome the confounding effect of corticosteroids and to allow for more accurate description of disease improvement and thus facilitate accurate investigations of new therapeutic agents.