A Postmarketing Study of Lecanemab for the Treatment of Participants With Alzheimer's Disease

The primary purpose of this study is to evaluate the safety of lecanemab-irmb in the real-world clinical setting as reported by events of amyloid-related imaging abnormalities (ARIA)-edema (ARIA-E), ARIA-hemosiderin deposition (ARIA-H), symptomatic ARIA-E, symptomatic ARIA-H, and intracerebral hemorrhage (ICH) greater-than 1 cm in participants treated with lecanemab-irmb. The secondary purpose of this study is to: Evaluate the safety of lecanemab-irmb in the real-world clinical setting as reported by events of seizures, anaphylaxis, central nervous system (CNS) ischemic event, and death. Assess the safety of lecanemab-irmb when stratified by baseline characteristics including apolipoprotein E (APOE) genotype, baseline magnetic resonance imaging (MRI) findings consistent with a high risk for cerebral amyloid angiopathy (CAA), prior Alzheimer's Disease (AD) treatments, and antithrombotic therapy. Assess the risk of safety outcomes (ARIA-E, ARIA-H, ICH greater than 1 cm, seizures, anaphylaxis, CNS ischemic event, and death) associated with APOE genotype, baseline MRI findings consistent with high risk for CAA, prior AD treatment, and antithrombotic therapy within participants exposed to lecanemab-irmb in ALZ-NET. Assess the risk of safety outcomes (ARIA-E, ARIA-H, ICH greater than 1 cm, seizures, anaphylaxis, CNS ischemic event, and death) between participants exposed to lecanemab-irmb in ALZ-NET and subjects exposed to lecanemab irmb in Study 301. Assess the risk of safety outcomes (ARIA-E, ARIA-H, ICH greater than 1 cm, seizures, anaphylaxis, CNS ischemic event,and death) between participants exposed to lecanemabirmb in ALZ-NET and subjects exposed to placebo (PBO) in Study 301. Assess the risk of safety outcomes (ARIA-E, ARIA-H, ICH greater than 1 cm, seizures, anaphylaxis, CNS ischemic event, and death) between participants exposed to lecanemab-irmb in ALZ-NET and participants not exposed to anti-amyloid therapies in ALZ-NET. Assess whether the risk of safety outcomes associated with APOE genotype, baseline MRI findings consistent with high risk for CAA, prior Alzheimer's Disease treatments, and antithrombotic therapy differs between participants exposed to lecanemab-irmb in ALZ-NET versus those not exposed to anti-amyloid therapies in ALZ-NET.