Supplementary Material for: Prevalence and outcome of cerebral microbleeds in antiphospholipid syndrome

Introduction: Antiphospholipid syndrome (APS) is an acquired autoimmune disease characterized by arterial and venous thrombosis. Acute ischemic stroke (AIS) and transient ischemic attack (TIA) are common neurological manifestations in APS patients. Cerebral microbleeds (CMB) are indicators for cerebral small vessel disease and associated with intracerebral hemorrhage (ICH) and AIS. In the present study, we aimed to look at the association and clinical significance of CMB in patients with APS. Methods: This is a retrospective cohort study that utilized data obtained from health service data of more than 5 million patients. We included patients aged 18 and older diagnosed with APS who underwent brain MRI between January 2014 and April 2020 and an age-matched control group with negative APS laboratory results. APS diagnosis was confirmed by positive laboratory findings from two separate tests conducted at least 12 weeks apart. The first available brain MRI was assessed for the presence of CMB. We compared the prevalence of CMB between patients with APS and controls. Among APS patients, we assessed the association between CMB and future AIS/TIA or ICH during 48-months follow-up using cox proportional hazards models. Results: The study included 276 patients, of which 195 were in the APS group and 81 in the control group. Patients with APS exhibited a higher prevalence of CMB (16% vs. 4%, p<0.01). Among the APS group, those with CMB had a significantly higher risk of subsequent AIS/TIA (Hazard ratio = 8.5, 95% CI 3.1-23, cumulative incidence 30% (95% CI, 13%-50%). None of the patients with APS had ICH during follow-up. Conclusion: Patients with APS have a higher prevalence of CMB compared with non-APS individuals, and the presence of CMB in APS patients is associated with an increased risk of AIS/TIA.