Study design of SEASON registry: prospective Surveillance of cardiovascular Events in an Antiplatelet-treated arterioSclerosis Obliterans patients in JapaN )SEASON).

Antiplatelet therapy is widely performed for arteriosclerosis obliterans (ASO) to relieve ischemic symptoms and prevent cardiovascular events. However, the overall rate of cardiovascular events in patients with ASO under treatment with antiplatelet agents has not been fully investigated in Japan. The SEASON registry is a nationwide observational prospective cohort study designed to compile data from over 2,000 institutions across Japan, whose aims are to (1) understand the current status for the management of ASO and clarify the incidence of cardiovascular events in patients with ASO undergoing antiplatelet therapy, and (2) compare the effectiveness of sarpogrelate, a 5-HT(2A) receptor antagonist, in decreasing the event rate with those of other antiplatelet agents [UMIN ID: UMIN000003385]. The registry will recruit approximately 10,000 patients receiving antiplatelet therapy (8,000 patients for sarpogrelate and 2,000 for other antiplatelet agents), and the patients will be followed every 6 months during a two-year follow-up period. The investigators plan to report all cardiovascular events and exacerbations of ASO. Analysis focusing on the sarpogrelate-treated subgroup will also be performed. Exploratory analysis will be performed to determine the clinical characteristics of the patients and to elucidate the relationships between risk factors and cardiovascular events. The SEASON registry is the first attempt to create a nationwide database regarding the incidence of cardiovascular events in 10,000 ASO patients in Japan. In addition, it ultimately may enable us to conclude that sarpogrelate prevents cardiovascular events. Information on the severity and risk factors in ASO patients in the clinical settings will be applicable to epidemiological analysis.