Background/Purpose: Primary thrombosis prophylaxis among asymptomatic antiphospholipid antibody (aPL) carriers is challenging. The presence of aPL does not always lead to thromboembolic events. Additional factors are needed to potentiate thrombus formation. A risk stratification tool to guide primary thrombosis prophylaxis among aPL positive carriers does not yet exist. Our study aims to evaluate the role of ASCVD score in primary thrombosis prophylaxis among asymptomatic aPL carriers.

Methods: This study included a convenience cohort of 198 persistent aPL positive patients who attended clinic at University of Texas Southwestern Medical Center. All patients had persistent high titer (≥99 percentiles) aPL. LA was tested by dilute Russell’s viper venom time, partial thromboplastin time–LA and silica clotting time, with appropriate cut-offs established in the laboratory. ASCVD is calculated based on patients’ age, total cholesterol, HDL, most recently documented systolic blood pressure, diabetes status, and smoking status. Pearson Chi-squared analysis was used to determine the association between increased ASCVD>10 and various thromboembolic events. Non-parametric comparison of ASCVD as a continuous variable was performed among different groups.

Results: Of the 198 aPL positive patients, 38 (19.2%) patients had arterial thrombosis, 72 (36.3%) had venous thrombosis, 7 had both arterial and venous thrombosis, and 95 (48.0%) were asymptomatic. Significantly higher 10-year CVD risk was seen among aPL patients with arterial thrombosis compared to asymptomatic carriers (P<0.0001). When comparing thrombotic APS patients to asymptomatic aPL positive carriers, 10-year CVD risk >7.5% (OR= 2.202, 95% CI 1.043–4.556, P=0.042) and 10-year CVD risk >10% (OR= 2.321, 95% CI 1.089-5.153, P=0.029) were significantly associated with arterial thrombosis but not venous thrombosis or any thrombosis. There were no significant CVD risk differences observed between aPL patients with venous thrombosis/or any thrombosis and asymptomatic carriers.

Conclusion: Increased 10 year cardiovascular disease risk determined by ASCVD among aPL positive patients is significantly associated with arterial thrombosis but not venous thrombosis. Since the protective effect of aspirin against incident thrombosis in all aPL carriers is not supported by randomized controlled data, our result suggests that ASCVD may be useful in identifying a subgroup of aPL carriers who benefit from aspirin.

ACR Meeting Abstracts - https://acrabstracts.org/abstract/assessing-the-role-of-ascvd-score-in-primary-thrombosis-prophylaxis-strategy-among-asymptomatic-antiphospholipid-antibody-carriers/