Real world application of the 2023 ACR/EULAR antiphospholipid antibody syndrome classification criteria in a pharmacist directed anticoagulation clinic

OBJECTIVES: To determine the number of patients that met classification for antiphospholipid antibody syndrome (APS) after applying the 2023 American College of Rheumatology and the European Alliance for Associations of Rheumatology (ACR/EULAR) classification criteria, to identify reasons patients did not meet the new criteria, and determine the number of patients who were single, double, or triple positive based on laboratory criteria. METHODS: A single center, retrospective chart review of patients with APS on anticoagulation managed by ambulatory care clinical pharmacists. Data collected included patient demographics, type of anticoagulation, and clinical and laboratory criteria for APS as defined by the 2023 ACR/EULAR criteria. Data is presented using descriptive statistics. RESULTS: A total of 51 patients previously diagnosed with APS were included. There were 42 patients on warfarin (82.3%), 4 patients on direct oral anticoagulants (19%), 3 patients on low molecular weight heparin (5.8%), and 2 patients on fondaparinux (3.9%). Of the 51 patients, 12 (23.5%) met classification criteria, 33 (64.7%) did not meet classification criteria and 6 (11.7%) had insufficient data. Of the 27 patients that did not meet criteria, 13 patients did not meet the laboratory criteria (39.4%), 6 patients did not meet the clinical criteria (18.2%) and 14 patients did not meet both laboratory and clinical criteria (42.4%). Of the 12 patients that met classification criteria, 2 patients were triple positive (16.7%), 3 were double positive (25%), and 7 were single positive (58.3%). CONCLUSIONS: Results from this study indicate that APS continues to be a complex disease state with challenges in diagnosis and classification. Since only a small number of patients in our clinic continued to meet the classification criteria, opportunities for patient re-evaluation of management strategies at our institution could be considered.