Investigators from the Antiphospholipid Syndrome Alliance for Clinical Trials and International Networking (APS ACTION) presented new research findings in antiphospholipid syndrome (APS) at the American College of Rheumatology (ACR) Convergence 2024, the ACR’s annual meeting. 

Hospital for Special Surgery (HSS), one of the leading centers in the United States providing care for adults and children with APS, is the lead coordinating center for APS ACTION, an international research network of 47academic institutions dedicated to advancing the understanding and management of APS. APS ACTION conducts large, multicenter clinical studies and trials in patients with positive antiphospholipid antibodies (aPL). 

APS is a systemic autoimmune disorder characterized by the production of aPL, which attacks proteins binding the cell walls of blood cells located on the inner layer of veins and arteries. APS increases the risk of dangerous blood clots, strokes, heart attacks and pregnancy complications. 

APS ACTION created the APS ACTION Clinical Database and Repository (APS ACTION Registry) to study the natural course of disease in patients with persistently positive aPL, with or without other systemic autoimmune diseases. Investigators worldwide collect blood samples and clinical data annually and follow patients for at least 10 years. As of November 2023, the registry included samples and data for about 1,200 patients. 

“Since the registry began in 2010, APS ACTION investigators have published 32 studies in peer-reviewed journals and delivered 71 podium and poster presentations at international congresses,” said Doruk Erkan, MD, MPH, a physician-scientist at the Barbara Volker Center for Women and Rheumatic Diseases and rheumatologist at HSS. Dr. Erkan is also a founding member of APS ACTION and the current chair of its Executive Committee. “We are thrilled to see seven new APS ACTION studies presented at ACR Convergence 2024, which will further advance our understanding of APS and it’s complexities.” 

Three of These Studies Based on APS ACTION Registry Clinical Data: 

Antiphospholipid Antibody-related Clinical Manifestations Presenting During Childhood versus Adulthood: Descriptive Results from the APS ACTION Registry

Antiphospholipid syndrome (APS) in pediatric patients remains largely understudied due to the rarity of APS in children. This APS ACTION study investigates the initial presentation of antiphospholipid antibody-positive patients, and compares the clinical characteristics of pediatric- (0-17 year old) versus adult-(18-75 year-old) onset disease. Unlike adults who often experience vascular events such as blood clotting, pediatric-onset patients show a notably higher frequency of non-vascular events, such as autoimmune hemolytic anemia or autoimmune thrombocytopenia (low platelet counts), at the time of diagnosis. The findings reveal that autoimmune blood disorders are common in children with APS at diagnosis. This study is important for helping physicians diagnose APS in children, highlighting the need to pay closer attention to non-vascular events, which may be often overlooked as diagnostic features of APS.

Clinical and Biologic Predictors of Thrombosis in Persistently Antiphospholipid Antibody Positive Patients: Prospective Analysis of the APS ACTION Registry

While antiphospholipid antibodies increase the risk of thrombosis, it is important to note that many of the individuals who have them do not experience a blood clot in a given year. This research aims to identify which patients carrying these antibodies are a high risk for blood clotting. The findings reveal that a history of blood clotting and autoimmune blood disorders such as autoimmune hemolytic anemia or autoimmune thrombocytopenia (low platelet counts) approximately doubles the risk of experiencing a new clotting event in patients with these antibodies. This study helps physicians in determining which patients are at higher risk of thrombosis, enabling more targeted monitoring and management strategies.

Natural History and Clinical Implications of Lupus Autoantibodies in Primary Antiphospholipid Antibody Positive Patients: Results from the APS ACTION Registry

While antibodies play a crucial role in our immune defense against infection, autoantibodies – found in autoimmune diseases – can mistakenly target the body’s own cells and tissues, leading to inflammation and, in the case of antiphospholipid antibodies, an increased risk of blood clots. In this study, patients with antiphospholipid antibodies were tested for other autoantibodies that are typically linked to lupus. Although it is known that many lupus patients also have antiphospholipid antibodies, less is understood about whether patients with only antiphospholipid antibodies (but no lupus diagnosis) may also have lupus-related antibodies. This study found that the prevalence of lupus autoantibodies in these patients ranged from 0% to 18%, depending on the specific autoantibody type, with anti-dsDNA, ANA and anti-SSA being the most common, while anti-Sm antibodies were not present. Patients with both antiphospholipid and lupus autoantibodies were more likely to have certain autoimmune blood disorders (low platelet counts or anemia), or microvascular disease. This research points to an important subgroup of patients who may need careful monitoring for potential complications.