Vascular Function in Hiroshima Atomic Bomb Survivors

Between August 2010 and June 2021, a total of 131 atomic bomb survivors were recruited for vascular function measurement from subjects who attended the outpatient clinic at Hiroshima University Hospital, and 3,966 control subjects who were not exposed to the atomic bomb were recruited from the Hiroshima University Hospital Vascular Registry. All of the atomic bomb survivors who participated in the study consented to the measurement and study participation, and those who did not consent were excluded. An atomic bomb survivor was defined as an individual who was formally issued an Atomic Bomb Health Handbook based on the law concerning assistance for atomic bomb survivors and who met one or more of the following conditions: having been directly exposed within a few kilometers of the hypocenter of the atomic bomb, having entered within two kilometers of the hypocenter within 2 weeks after the bombing, having been engaged in rescue or other related activities, and having been exposed in utero. The cohort of Atomic Bomb Survivors in Hiroshima (ABS) included about 290,000 atomic bomb survivors in Hiroshima who were issued an Atomic Bomb Health Handbook. ABS was a cohort study that was started in 1971 by the Research Institute for Radiation Biology and Medicine of Hiroshima University. Details of the ABS study methods were described previously (22 (link)). Of the 3,966 control subjects, 2,813 subjects who were less than 65 years old were excluded because this study was started 65 years after the atomic bombing and the youngest age of the atomic bomb survivors was 65 years. Finally, 1,153 control subjects were enrolled in this study. Diabetes mellitus was defined according to the criteria provided by the American Diabetes Association or a previous diagnosis of diabetes (23 (link), 24 (link)). The definition of dyslipidemia was based on the third report of the National Cholesterol Education Program (25 (link)).
All measurements were done in the morning, after overnight fasting, in a quiet, dark, air-conditioned room (constant temperature of 22–25°C) during the study. FMD, NID, baPWV, and brachial artery IMT were measured, after maintaining the supine position for 30 min. The observers masked the clinical characteristics of the subjects and the aim of the study. All methods were carried out according with the Declaration of Helsinki and relevant guidelines and regulations. The study was approved by the Ethics Review Board of Hiroshima University. Written informed consent was obtained from all subjects.