Svenungsson E, Gustafsson JT, Grosso G, et al. - Researchers tried to find out if platelet C4d (PC4d) adds additional value to traditional and known lupus-associated risk factors when distinguishing SLE patients with vascular disease. A cross-sectional study was designed to include 308 well-characterized SLE patients and 308 matched general population controls. Flow cytometry was applied to evaluate PC4d deposition. Compared with population controls, SLE patients had increased PC4d deposition. The results showed that PC4d+ is correlated with vascular events in SLE, independently of traditional and SLE-associated risk factors. It was noted that concurrent presence of PC4d and LA appear to interact to additional improve the odds for vascular events. Prospective studies should evaluate if the aPL/PC4d combination can enhance prognostication of vascular events in SLE and/or APS.