Comparative study between obstetric antiphospholipid syndrome and obstetric morbidity related with antiphospholipid antibodies

Background and objectives: To compare clinical, laboratory, treatment and live birth rate data between women with aPL-related obstetric complications (OMAPS) not fulfilling the Sydney criteria and women fulfilling them (OAPS). Materials and methods: Retrospective and prospective multicentre study. Data comparison between groups from The European Registry on Antiphospholipid Syndrome included within the framework of the European Forum on Antiphospholipid Antibody projects. Results: 338 women were analysed: 247 fulfilled the Sydney criteria (OAPS group) and 91 did not (OMAPS group). In the OMAPS group, 24/91 (26.37%) fulfilled laboratory Sydney criteria (subgroup A) and 67/91 (74.63%) had a low titre and/or non-persistent aPL-positivity (subgroup B). Overall, aPL laboratory categories in OAPS vs. OMAPS showed significant differences: 34% vs. 11% (p < 0.0001) for category I, 66% vs. 89% (p < 0.0001) for category II. No differences were observed when current obstetric complications were compared (p = 0.481). 86.20% of OAPS women were treated vs. 75.82% of OMAPS (p = 0.0224), particularly regarding the LDA + LMWH schedule (p = 0.006). No differences between groups were observed in live births, gestational, puerperal arterial and/or venous thrombosis. Conclusions: Significant differences were found among aPL categories between groups. Treatment rates were higher in OAPS. Both OAPS and OMAPS groups had similarly good foetal-maternal outcomes when treated. The proposal to modify OAPS classification criteria, mostly laboratory requirements, is reinforced by these results.