**3.4 Does the pattern of antibody positivity influence the likelihood of stroke?**

As outlined in **Table 7**, some aPL are associated with a higher risk of ischemic stroke than others. Isolated LA positivity induces the greatest individual antibody risk for ischemic stroke [58]. Anti- β2-GPI were also associated with increased risk but to a lesser degree [58]. aCL and antiprothrombin antibodies have been reported variably with some studies showing no increased risk as an independent risk factor [27] while others reported to be independent risk when considering young patients exclusively [58]. As mentioned, triple positivity with positive LA, β2-GPI antibodies and aCL antibodies confers the highest risk [58].


**Table 7.**

*Risk for cerebrovascular event based on serologic profile. Adapted [58].*

## **3.5 Does the presence of other risk factors for cerebrovascular events increase the risk in patients with APS?**

Traditional cardiovascular risk factors also play a role in outcomes for patients with APS. Studies reveal that hypertension and smoking are the risk factors most associated with repeat thrombotic arterial events [59]. Combinations of risk factors have also been shown to increase the risk of repeat events [60]. Prospective studies evaluating the results of risk factor control have yet to be reported.

The RATIO study (Risk of Arterial Thrombosis In relation to Oral contraceptives) identified that the use of oral contraceptives (OCPs) and smoking carried an extremely high risk for women with APS in terms of risk for myocardial infarction and ischemic stroke [28]. The data revealed that the relative risk for ischemic stroke was higher in those who were smoking and in women with OCPs. The odds ratio for ischemic stroke was 43.1 (95%CI 12.2–152.0), which increased to 201.0 (95%CI 22.1–1828.0) in women who used oral contraceptives and 87.0 (14.5–523.0) in those who smoked. In women who had anti- β2-GPI, the risk of ischemic stroke was 2.3 (95%CI 1.4–3.7), but the risk of myocardial infarction was not increased (OR 0.9, 95%CI 0.5–1.6). Neither aCL nor anti-prothrombin antibodies affected the risk of myocardial infarction or ischemic stroke [28].
