RP 7-09

Study of Arteriosclerosis in the Adult Health Study Population (Part 1. Physiological Indices of Arteriosclerosis)

Summary

Past studies have reported significant association between radiation exposure and atherosclerotic disease mortality/morbidity among A-bomb survivors. Atherosclerosis comprises two aspects: atherosis (fatty degeneration) and sclerosis (acceleration of arterial stiffness), both of which are semi-independently related to atherosclerotic disease. In this study, measures pertaining to atheroma include the ankle-brachial index (ABI), toe-brachial index (TBI), and intima-media thickness (IMT), while those used for arterial stiffness include the augmentation index (AI) and brachial-ankle pulse wave velocity (baPWV). Although acceleration of arterial stiffness might be caused by structural changes in arterial walls, the association of radiation and radiation-induced injury and repair of arterial walls has not been fully investigated.

In this study, we hypothesize that radiation exposure is a significant risk factor for arterial stiffing. We propose to conduct a cross-sectional study to obtain measurements of atherosclerosis and arterial stiffness. The study cohort will comprise about 4,000 Adult Health Study (AHS) subjects, including the expanded AHS group of younger subjects. The associations of radiation and the aforementioned arteriosclerosis indices will be analyzed using the generalized estimating equations (GEE) model to account for correlation among the indices, with due consideration paid to atheromatous disease indices (ABI/TBI, IMT, etc.) and arteriosclerosis risk factors (Framingham risk scores; FRS).

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