Longitudinal observation of thrombotic events in patients with obstetric antiphospholipid syndrome.

Abstract

ObjectiveWe aimed to investigate the long-term thrombotic outcomes in patients with obstetric antiphospholipid syndrome (OAPS) who initially presented without thrombosis and to identify clinical features associated with late thrombotic events.MethodsFemale patients with antiphospholipid syndrome (APS) and obstetric manifestations diagnosed at Hokkaido University Hospital between 2004 and 2024 were retrospectively analyzed. Patients were first compared cross-sectionally according to the presence or absence of a history of thrombosis at diagnosis. Among those without prior thrombosis, individuals were further analyzed in a nested case-control study comparing patients who developed new thrombotic events with those who remained event-free for more than 10 years.ResultsOf 47 female APS patients complicated with obstetric manifestations, 23 had a history of thrombosis but not in 24 patients. The prevalence of SLE was higher in the thrombotic group (74%) compared with 40% in the non-thrombotic group (p = 0.019, Fisher's exact test). During long-term follow-up, 4 of the 24 patients in the absence of prior thrombosis developed a first thrombotic event median of 16 years after the diagnosis. Of the remaining 20 OAPS patients, 9 patients who were observed for more than 10 years without any thrombotic events served as the control group and 11 patents with less than 10 years of follow-up were excluded. The presence of triple antiphospholipid antibodies (aPLs) and accumulation of conventional thrombotic risk factors were more frequent among the cases than the controls.ConclusionThrombotic events may occur in OAPS patients even decades after diagnosis of OAPS, particularly in those with high-risk aPL profiles and conventional thrombotic risk factors. These findings underscore the importance of long-term vigilance and individualized prevention strategies in OAPS management.