['To determine whether the Systemic Lupus Erythematosus Disease Activity Index 2000 (SLEDAI-2K) is valid in identifying patients who had a clinically important overall improvement with no worsening in other descriptors/systems.', 'Consecutive patients with systemic lupus erythematosus with active disease who attended the Lupus Clinic between 2000 and 2012 were studied. Based on the change in the total SLEDAI-2K scores on last visit, patients were grouped as improved, flared/worsened, and unchanged. Patients showing improvement were evaluated for the presence of new active descriptors at last visit compared with baseline visit.', 'Of the 158 patients studied, 109 patients had improved, 38 remained unchanged, and 11 flared/worsened at last visit. In the improved group, 11 patients had a new laboratory descriptor that was not present at baseline visit. In those 11 patients, this new laboratory descriptor was not clinically significant and did not require a change in disease management.'] Does sLEDAI-2K Conceal Worsening in a Particular System When There Is Overall Improvement?