Primary Thrombosis Prophylaxis in Antiphospholipid Antibody–Positive Patients: Where Do We Stand?

Persistently positive antiphospholipid antibodies (aPLs) with thrombosis and/or pregnancy morbidity are the hallmark of the antiphospholipid syndrome. However, aPL-positive patients with no prior history of thrombosis exist. On the basis of a limited number of studies that predominantly included systemic lupus erythematosus patients, aPL-positive patients without previous thrombosis have a 0% to 3.8% annual incident thrombosis risk. Given that every positive aPL test is not clinically significant and every aPL-positive patient does not have the same thrombosis risk, risk stratification (based on aPL profile, age, systemic autoimmune diseases, and traditional cardiovascular disease or venous thrombosis risk factors) is crucial to determine the first thrombosis risk in aPL-positive patients. The optimal primary thrombosis prevention strategy in patients with clinically significant aPL profiles should include 1) regular monitoring and elimination of non-aPL thrombosis risk factors, 2) aggressive management of clinical and subclinical systemic autoimmune disease activity, and 3) patient counseling and education. The protective effect of low-dose aspirin against incident thrombosis in patients with clinically significant aPL profiles is not supported by randomized controlled data; general population cardiovascular disease risk prediction tools and prevention guidelines formulated based on risk–benefit calculations should play a role in the decision whether to recommend low-dose aspirin. The effectiveness of hydroxychloroquine, statins, or their combination remains to be determined by well-designed randomized controlled trials.