Increased circulating apoptotic endothelial cells (CD146AnnV+) predict vascular impairment. Patients with SLE were subdivided into 2 subgroups on the basis of their levels of circulating apoptotic ECs per milliliter, using a cutoff of 85 cells/mL which corresponded to the 75th percentile among the patients with lupus. Therefore, 85 cells/mL or more is designated as a high number of circulating CD146^AnnV+ cells, and less than 85 cells/mL is designated as low CD146^AnnV+; *P = .0026 by t test. FMD indicates flow-mediated vasodilation.