Recurrent miscarriage and thrombosis in Asian antiphospholipid syndrome: a systematic review

Antiphospholipid syndrome (APS) is an autoimmune prothrombotic state defined by vascular thrombosis and adverse pregnancy outcomes, most notably recurrent miscarriage. While APS epidemiology is well characterized in Western populations, comprehensive data from Asia remain fragmented. This systematic review (PRISMA-compliant) synthesized evidence from 22 studies across eight Asian countries, encompassing over 40,000 individuals, including nationwide registries, APS cohorts, and high-risk groups such as systemic lupus erythematosus (SLE), recurrent pregnancy loss (RPL), and malignancy. Population-based studies from South Korea and Taiwan reported an APS incidence of 0.50-0.82 per 100,000 person-years and prevalence of 5-7 per 100,000, with female predominance. Among women with RPL, APS prevalence ranged from 5% to 22.9%; Japanese studies identified an aPL-positive rate of 8.7% in 5708 women and a novel anti-β2GPI-HLA-DR autoantibody in 22.9% of RPL patients, while a Chinese cohort reported APS in 10.3% of women with fetal death. In obstetric APS cohorts, antithrombotic therapy was consistently associated with improved live birth rates. Beyond pregnancy morbidity, more than half of APS patients experienced thrombotic events, with comparable frequencies of venous and arterial thrombosis; ischemic stroke was particularly prominent in SLE-associated APS. Catastrophic APS occurred in 1-5% of patients, with annual thrombosis recurrence of 4-10%. These findings demonstrate that although APS is rare at the population level in Asia, it carries a disproportionately high burden of both recurrent miscarriage and thrombotic events. From a reproductive immunology perspective, systematic aPL screening in women with unexplained RPL represents a high-yield strategy to improve pregnancy outcomes in Asian populations.