Clin Exp Rheumatol. 2025 Jul 21. doi: 10.55563/clinexprheumatol/t0xgtk. Online ahead of print.
ABSTRACT
OBJECTIVES: To assess risk factors for rethrombosis, the intensity and maintenance of anticoagulation in primary antiphospholipid syndrome (APS).
METHODS: We retrospectively included 81 patients with thrombotic APS under VKAs with ≥4 INR determinations per year in at least 1 year. We defined an index period as the time between the first available INR value and the next thrombotic event, or the time between the first and last available INR if rethrombosis-free. We recorded demographic and clinical/serologic variables, mean INR, mean INR-AUC, and anticoagulation intensity (INR<2.5, INR 2.5-3.5, and INR>3.5). For the statistical analysis we used Cox survival analysis, hazard function (H(t)) curves and AUC.
RESULTS: The median follow-up time was 6.4 years. 64 patients had no rethrombosis, whereas 17 did (15 arterial, 2 venous). The risk factors for rethrombosis were number of previous rethrombosis (RR 7.3 95% CI 2.3-322.7, p=0.007) and INR intensity (RR 0.03, 95% CI 0.002-0.367, p=0.001). Results were similar when only arterial events were analysed. At the H(t) curves, the cumulative risk was higher in patients with an INR <2.5 than those in an INR of 2.5-3.5. A mean INR of 2.2 identified patients at risk of rethrombosis (SE=0.82, SP=0.20, AUC=0.42).
CONCLUSIONS: The number of previous thrombotic events and the intensity of anticoagulation are rethrombosis risk factors. An INR ranging 2.5-3.5 protects against re-thrombosis, including arterial events.
PMID:40693427 | DOI:10.55563/clinexprheumatol/t0xgtk
