Fasting and non-fasting triglycerides and risk of ischemic cardiovascular disease in Japanese men and women: The Circulatory Risk in Communities Study (CIRCS)
Introduction
Although the impact of total and LDL-cholesterols on ischemic cardiovascular disease has been well established [1], the impact of triglycerides has remained controversial. Large meta-analyses, primarily performed in western countries [2], [3], [4], but not all [5], have identified moderate and statistically significant associations between triglycerides and risk of ischemic heart disease, stroke, or cardiovascular events, even after adjustment for cardiovascular risk factors including body mass index, diabetes mellitus and HDL-cholesterol. The evidence for Asian populations is limited, but a previous study of ours [6], [7] and a meta-analysis by Asia Pacific Cohort Studies Collaboration [8] detected an independent relationship between triglycerides and risk of coronary heart disease. Furthermore, emerging evidence from western countries supports the notion that non-fasting triglycerides, a postprandial state of lipid profile, is an even better predictor of ischemic cardiovascular disease [9], [10], [11], [12].
High levels of non-fasting triglycerides reflect increased residues from chylomicrons and very low density lipoproteins. These cholesterol-containing and triglyceride-rich lipoprotein residues penetrate the arterial intima and are trapped within the arterial wall, leading to the development of atherosclerosis [13], [14], [15]. It remains to be determined, however, whether populations such as Japanese, with lower levels of total- or LDL-cholesterol and triglycerides, run a similar potential risk of high postprandial triglyceride levels.
Associations between non-fasting and fasting triglycerides and risk of incident cardiovascular disease in Asian countries have not been investigated systematically in any cohort studies. We hypothesized that non-fasting triglycerides constitute a better predictor for ischemic cardiovascular disease than fasting triglycerides in Asian populations whose prevalence of dyslipidemia is lower than that in western populations. To test our hypothesis, we examined the data of the Circulatory Risk in Communities Study (CIRCS), community-based prospective study of approximately 10,000 middle-aged Japanese men and women.
Section snippets
Study population
The surveyed population comprised 11,370 residents aged 40–69 years in four communities: Ikawa town (a rural community in Akita Prefecture in northwestern Japan), the Minami-Takayasu district in Yao City (a southwestern suburb in Osaka Prefecture), Noichi town, (a rural community in Kochi Prefecture in southwestern Japan) and Kyowa town (a rural community in Ibaraki Prefecture in central Japan) [16], [17]. The baseline surveys were conducted in 1975–1980, 1975–1984, 1975–1980, and 1981–1986,
Results
Table 1 lists sex-specific, age-adjusted mean values and prevalence of selected cardiovascular risk factors at baseline in relation to serum triglyceride quintiles and stratified by fasting status. For both fasting and non-fasting status, triglyceride levels were positively associated with body mass index, systolic and diastolic blood pressure levels, antihypertensive medication, hypertension, serum total cholesterol levels and serum glucose levels, and inversely associated with HDL-cholesterol
Discussion
For our large, long-term prospective cohort of Japanese middle-aged residents, we found that, independent of other major cardiovascular risk factors, serum triglycerides levels were positively associated with risk of ischemic cardiovascular disease, and of either ischemic heart disease or ischemic stroke. These associations were more marked for ischemic heart disease than for ischemic stroke. When stratified by fasting status, these associations did not differ substantially between fasting and
Author contributions
The authors made the following contributions: H.I.(first author) researched data, conducted the analyses and drafted the manuscript; H.I. (second author) researched data, contributed to the discussion and edited the manuscript; K.Y. researched data, coordinated the implementation of research at Kyowa and contributed to the discussion; T.Ohira, R.C., H.N., T.Okada, S.H., T.T. researched data and contributed to the discussion; S.S. researched data, coordinated the implementation of research at
The CIRCS Investigators
Yoshinori Ishikawa, Akihiko Kitamura, Masahiko Kiyama, Masakazu Nakamura, Takeo Okada, Masakazu Nakamura, Masatoshi Ido, Kenji Maeda, Mitsumasa Umesawa, Isao Muraki, Yuji Shimizu, Takashi Shimamoto, Minoru Iida and Yoshio Komachi, Osaka Medical Center for Health Science and Promotion; Shinichi Sato, Chiba Prefectural Institute of Public Health; Yoshihiko Naito, Mukogawa Women's University; Hideki Ozawa, Oita University Faculty of Medicine; Kazumasa Yamagishi, Choy-Lye Chei and Tomoko Sankai,
Competing interest
None declared.
Acknowledgments
This study was supported in part by a Grant-in-Aid for Scientific Research A [grant number 04304036], Scientific Research B [grant numbers 02454209, 50223053, 06454234, 08457125, 10470103 and 12470092], Scientific Research C [grant numbers 19590629 and 19590663], and Exploratory Research [grant number 15659146] from the Japan Society for the Promotion of Science.
The authors wish to thank the research staff of the Osaka Medical Center for Health Science and Promotion (presently, Osaka Center for
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