Thrombotic Antiphospholipid Syndrome: A Long Term Follow‐up of Patients With Recurrent Pregnancy Loss and Antiphospholipid Antibodies From the APS 1994 Study

PROBLEM: There is a paucity of studies on the incidence and predictors of thrombotic antiphospholipid syndrome (APS) after pregnancy in patients with recurrent pregnancy loss (RPL) and antiphospholipid antibodies (aPL). This prospective study aimed to assess the long-term prognosis, including the occurrence of thrombosis and associated risk factors, in patients with aPL-positive RPL and related obstetric APS manifestations. METHOD OF STUDY: We examined patients with RPL and related obstetric APS manifestations who were positive for lupus anticoagulant (LA) based on APTT, Russell's viper venom time (RVVT), or β2glycoprotein I-dependent anticardiolipin antibody (β2GPIaCL) IgG and visited Nagoya City University Hospital from 1994 to 2019. A survey was conducted in 2024 in which patients were asked to complete a questionnaire on the development of APS manifestations based on the American College of Rheumatology/European Alliance of Associations for Rheumatology classification criteria. RESULTS: Data of 259 of 285 patients (90.5%) who responded to the questionnaire were analysed. The median follows-up duration was 17 (4.6-31.1) years. Cumulatively, 9.6% (25/259) of patients with aPLs and 15.7% (18/114) of those with obstetric APS experienced thrombotic APS. LA-APTT, LA-RVVT, and β2GPIaCL IgG were independent predictors of thrombotic APS, with area under the curve values of 0.85 (0.73-0.97), 0.93 (0.87-0.99), and 0.80 (0.68-0.93), respectively. A history of intrauterine foetal death, early-onset preeclampsia, no live birth, thrombosis and complications of systematic lupus erythematosus, and persistent aPL were predictive of thrombotic APS. CONCLUSION: Patients with RPL and aPL who exhibit the identified risk factors should undergo subsequent follow-up after pregnancy. Further research is required to investigate the potential for thrombosis prevention.