CO102 | VARIABILITY IN ANTIPHOSPHOLIPID ANTIBODY TESTING AND TREATMENT STRATEGIES IN OBSTETRIC ANTIPHOSPHOLIPID SYNDROME: RESULTS FROM THE OAPS-CARE SURVEY, ON BEHALF OF THE EUROPEAN FORUM ON ANTIPHOSPHOLIPID ANTIBODIES

A. Hoxha^1|2, E. Esteve-Valverde^3|4, G. Gobbo^1|2, F. Miró-Mur⁴, M. Radin⁵, S. De Carolis⁶, C. Trilla^7|8|9|10, A. Tincani^11|12, R. Cervera^13|14, J. Alijotas-Reig^3|15|16 | ¹Department of Medicine - DIMED, University of Padua, Padova, Italy; ²Internal Medicine Unit, Thrombosis and Bleeding Disorder, University Hospital of Padua, Padova, Italy; ³Systemic Autoimmune Diseases Unit. Department of Internal Medicine, Hospital Sant Camil, Consorci Sanitari Alt-Penedes-Garraf, Sant Pere de Ribas, Barcelona, Spain; ⁴Systemic Autoimmune Disease Research Unit. Vall d'Hebron Institut de Recerca (VHIR), Barcelona, Spain; ⁵Center of Research of Immunopathology and Rare Diseases - Coordinating Center of Piemonte and Valle d'Aosta Network for Rare Diseases, SCDU Nephrology and Dialysis, School of Specialization of Clinical Pathology, Department of Clinical and Biological Sciences, S. Giovanni Bosco Hospital, University of Turin, Torino, Italy; ⁶Fondazione Policlinico Universitario A. Gemelli IRCCS, Dipartimento di Scienze per la salute della Donna e del Bambino e di Sanità Pubblica, Roma, Italy; ⁷Hospital de la Santa Creu i Sant Pau, Barcelona, Spain; ⁸Universitat Autònoma de Barcelona, Barcelona, Spain; ⁹Spanish Network in Maternal, Neonatal, Child and Developmental Health Research (RICORS-SAMID, RD24/0013/0001), Instituto de Salud Carlos III, 28040 Madrid, Spain; ¹⁰Women and Perinatal Health Research Group, Institut de Recerca (IR SANT PAU), Sant Quintí 77-79, 08041 Barcelona, Spain; ¹¹Rheumatology and Clinical Immunology Unit - ERN ReCONNET, ASST Spedali Civili, Brescia, Italy; ¹²Department of Clinical and Experimental Sciences, University of Brescia, Brescia, Italy; ¹³Department of Autoimmune Diseases, Hospital Clínic, University of Barcelona, Barcelona, Catalonia, Spain; ¹⁴August Pi i Sunyer Biomedical Research Institute (IDIBAPS), Barcelona, Catalonia, Spain; ¹⁵Department of Medicine. Universitat Autonoma de Barcelona, Barcelona, Spain; ¹⁶Systemic Autoimmune Disease Unit, Department of Internal Medicine, Vall d’Hebron University Hospital, Barcelona, Spain

Background and aims. Obstetric antiphospholipid syndrome (OAPS) is a major cause of pregnancy morbidity characterized by placental insufficiency, fetal loss, and recurrent miscarriage in association with persistent antiphospholipid antibodies (aPL). Despite international classification criteria and therapeutic recommendations, substantial variability remains in real-world practice. To address this gap, the Obstetric Antiphospholipid Syndrome: Clinical Assessment and Reproductive Evaluation (OAPS-CARE) survey was developed within the European Forum on Antiphospholipid Antibodies framework to document international, real-world practices for assessing and managing OAPS.
Methods. The OAPS-CARE study was designed as an international, cross-sectional, internet-based survey to assess current clinical practices in the diagnosis and management of OAPS. The survey was formulated by a multidisciplinary steering committee comprising rheumatologists, internists, obstetricians, and clinical immunologists with specialized knowledge on APS and pregnancy morbidity. The 60-item questionnaire addressed definitions of obstetric morbidity, indications, timing, interpretation of aPL testing, use of classification criteria, and treatment strategies across pregnancy scenarios.
Results. A total of 152 clinicians from 24 countries participated, of whom 123 (81%) completed the survey. The majority were rheumatologists (46.3%) and obstetricians/gynecologists (22.0%), mostly practicing in tertiary care centers. Recurrent miscarriage (93.5%), placental insufficiency (65.9%), and preeclampsia (56.1%) were the most frequently associated obstetric manifestations. Although lupus anticoagulant (98.2%), anticardiolipin (96.3%), and anti-β2-glycoprotein I antibodies (89.9%) were widely tested, variability emerged in timing, interpretation, and repeat testing practices. While most respondents recommended low-dose aspirin plus low-molecular-weight heparin in confirmed OAPS, management strategies diverged substantially between double/single aPL positivity and non-criteria scenarios. Adjunctive therapies, such as hydroxychloroquine, were inconsistently administered. In cases of refractory OAPS and high-risk pregnancies, most clinicians prefer to escalate treatment rather than continue the same regimen. Nearly half (46.1%) of practitioners would increase to therapeutic-dose LMWH plus LDA, while almost two-thirds (64.7%) would add HCQ from preconception, making HCQ the most recommended adjunctive strategy.
Conclusions. Our findings indicate that contemporary OAPS management operates in a hybrid space between classification-driven precision and phenotype-driven pragmatism. The predominance of small effect sizes across many comparisons indicates encouraging international alignment; however, the consistent variability in lower-risk and refractory scenarios reveals areas where guidance remains insufficiently operationalized. Future international recommendations should (i) harmonize obstetric definitions, (ii) standardize laboratory thresholds across assay platforms, and (iii) formalize risk-adapted escalation pathways integrating antibody profile, obstetric phenotype, and prior treatment response.