Antiphospholipid syndrome (APS) is an autoimmune disorder characterized by thrombosis and pregnancy morbidity in patients with persistently positive antiphospholipid antibodies (aPLs). However, large-scale research on general population with persistent aPLs has been lacking. This project proposes to establish the first multicenter cohort of patients with persistently positive aPLs in China and conduct a comprehensive clinical phenotyping study. Based on traditional phenotypes of thrombotic and pregnancy events, the focus will be on extra-standard clinical phenotypes and prospective assessment of event risk and prognosis in aPL-positive population. A prospective analysis of extra-standard antibodies will also be conducted to recommend detection criteria for extra-standard antibody application in China and to assess their clinical significance.