Background/Purpose: APS ACTION Registry was created to study the natural course of disease over 10 years in persistently antiphospholipid antibody (aPL)-positive patients. Previously, based on five new thrombotic events, we reported the one-year first and recurrent thrombosis risk in persistently aPL-positive patients as 0% and 1.7%, respectively (Erkan et al. Arthritis Rheumatol. 2015; 67 [suppl 10]). The objective was to report additional thrombotic events based on one-, two-, and three-year follow-up visits.

Methods: A web-based data capture system is used to store patient demographics, aPL-related history, and medications. The inclusion criteria are positive aPL based on the Updated Sapporo Classification Criteria at least twice within one year prior to enrollment. Patients are followed every 12±3 months; they also receive advice on cardiovascular disease and thrombosis prevention at each visit. We report the new events in a descriptive fashion.

Results: As of April 2016, 627 patients included in the APS ACTION Registry (aPL/APS without any other autoimmune disease: 410, and aPL/APS associated with another autoimmune disease: 217). Of 627 patients, 432 (67.7%), 244 (38.2%), and 43 (6.7%) completed their one-, two-, and three-year follow-up visits, respectively. Mean follow up times were 1.67 years (505 patient-years) and 1.65 years (215 patient-years) for those with and without a history of thrombosis, respectively. Based on a total of 12 recurrent (7 events during the 1^st year; 3 during the 2^nd year; and 2 during the 3^rd year) and four initial (2 events during the 1^st year; 1 during the 2^nd year; and 1 during the 3^rd year) events since the inception of the registry (Table), the incident thrombosis risk was 2.37 and 1.86 per 100 patient-years in patients with and without history of thrombosis, respectively. The annual thrombosis risk was 2.38% and 1.86% in patients with and without history of thrombosis, respectively.

Conclusion: The incident thrombosis risk is relatively low and commonly associated with lupus anticoagulant and/or triple aPL-positivity as well as non-aPL thrombosis risk factors in our multi-center international cohort. Annual and risk stratified analysis of APS ACTION registry will better determine the risk of thrombosis in persistently aPL-positive patients based on different risk profiles.  

*   At the time of recurrence ** Duration between the last thrombosis and recurrence in parenthesis *** History of recurrent thromboses ^ Patient with new events since the last analysis   AIDx: autoimmune disease; ASA: aspirin; CVD: cardiovascular disease; DM: diabetes mellitus; DVT: deep vein thrombosis; F: female; HL: Hyperlipidemia; HTN; hypertension; Immob/Sx: immobilization & postsurgical; INR: international randomization ratio: M: male; MI: Myocardial Infarction; PE: pulmonary embolism; PFO: patent foremen ovale; RF: renal failure defined as GFR < 60 ml/min; SLE: systemic lupus erythematosus., VT: Venous Thrombosis