Details of a Researcher - Okamura, Tomonori

Papers - Okamura, Tomonori

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Marital status and cardiovascular risk factors among middle-aged Japanese male workers

Kamon Yuko, Okamura Tomonori, Tanaka Taichiro, Hozawa Atsushi, Yamagata Zentaro, Takebayashi Toru, Kusaka Yukinori, Urano Sumio, Nakagawa Hideaki, Kadowaki Takashi, Miyoshi Yuji, Yamato Hiroshi, Okayama Akira, Ueshima Hirotsugu

Journal of Occupational Health 50 ( 4 ) 348 - 356 2008.07

ISSN 1341-9145

Marital status is related to cardiovascular disease (CVD) risk factors in Western countries. However, few studies have addressed the relationship between marital status and CVD risk factors in other populations. We investigated lifestyle and CVD risk factors relative to marital status among middle-aged Japanese men. We analyzed baseline data of 40-59-yr-old male workers who participated in the high-risk and population strategy for occupational health promotion (HIPOP-OHP) study. We compared lifestyle and CVD risk factors between men who were married (Group M; n=1,419, mean age 47.9 ±5.1 yr) and those who had never married (Group N; n=163, mean age 46.7 ±4.3 yr). Men in Group N were more likely to skip breakfast, work more shifts and exercise less. Current smoking rates, as well as average values of diastolic blood pressure (DBP), serum total cholesterol and fasting plasma glucose were also higher in Group N than in Group M. The proportion of participants with three or more CVD risk factors, namely smoking, hypertension, hypercholesterolemia and hyperglycemia was higher in Group N, than in Group M (12.9% vs. 5.0%, p<0.01). The difference between Groups M and N was more evident in the subgroup of living with others, than in the subgroup of living alone. Since men who have never married might be at higher risk for CVD, effort should be made to educate this population about decreasing lifestyle-related risk factors.

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Relationship between BMI and all-cause mortality in Japan

Hozawa Atsushi, Okamura Tomonori, Oki Izumi, Murakami Yoshitaka, Kadowaki Takashi, Nakamura Koshi, Miyamatsu Naomi, Hayakawa Takehito, Kita Yoshikuni, Nakamura Yosikazu, Nakamura Yasuyuki, Abbott Robert D., Okayama Akira, Ueshima Hirotsugu, Iimura Osamu, Omae Teruo, Ueda Kazuo, Yanagawa Hiroshi, Horibe Hiroshi, Kodama Kazunori, Kasagi Fumiyoshi, Tanihara Shinichi, Saito Shigeyuki, Sakata Kiyomi, Kakuno Fumihiko, Takeuchi Toshihiro, Hasebe Mitsuru, Kusano Fumitsugu, Kawamoto Takahisa, Minowa Masumi, Iida Minoru, Hashimoto Tsutomu, Tanaka Shigemichi, Terao Atsushi, Kawaminami Katsuhiko, Sawai Koryo, Shibata Shigeo

Obesity 16 ( 7 ) 1714 - 1717 2008.07

ISSN 1930-7381

As body composition in Asian populations is largely different from Western populations, a healthy BMI could also differ between the two populations. Thus, further study is needed to determine whether a healthy BMI in Asians should be lower than Western populations, as recommended by the World Health Organization (WHO). We investigated the relationship between BMI and mortality in a sample of 8,924 Japanese men and women without stroke or heart disease. During 19 years of follow-up, 1,718 deaths were observed. We found a U-shaped relationship between BMI and fatal events. Risk of total mortality was highest in participants with BMI <18.5 kg/m² and lowest in participants with BMI 23.0-24.9 kg/m². These findings persisted even after excluding the first 5 years of follow-up with a focus on healthy participants who never smoked, were aged <70 years, and had total cholesterol (TC) levels ≥4.1 mmol/l (N = 3712). For both the full sample and healthy participants, all-cause mortality risk did not differ between BMI ranges 21.0-22.9 and 23.0-24.9 kg/m². Our findings do not support the recent WHO implications that BMIs <23.0 kg/m² is healthy for Asians. Therefore, further studies are needed to identify an optimal BMI range for Asia. © 2008 The Obesity Society.

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Erratum

Hayashino Y., Fukuhara S., Okamura T., Yamato H., Tanaka H., Tanaka T., Kadowaki T., Ueshima H.

Diabetes Care 31 ( 7 ) 1471 2008.07

ISSN 0149-5992

Relation of blood pressure and all-cause mortality in 180 000 japanese participants pooled analysis of 13 cohort studies

Murakami Yoshitaka, Hozawa Atsushi, Okamura Tomonori, Ueshima Hirotsugu

Hypertension 51 ( 6 ) 1483 - 1491 2008.06

ISSN 0194-911X

Hypertension is a leading cause of death because of cardiovascular disease and predominantly affects total mortality. To reduce avoidable deaths from hypertension, we need to collect blood pressure data and assess their impact on total mortality. To examine this issue, a meta-analysis of 13 cohort studies was conducted in Japan. Poisson regression was used for estimating all-cause mortality rates and ratios. In the model, blood pressure data were treated as continuous (10-mm Hg increase) and categorical (every 10 mm Hg) according to recommendations of the Seventh Joint National Committee on Prevention, Detection, Evaluation, and Treatment of Hypertension. Potential confounders included body mass index, smoking, drinking, and cohort. The impact of hypertension was measured by the population-attributable fraction. After excluding participants with cardiovascular disease history, 176 389 participants were examined in the analysis. Adjusted mortality rates became larger as the blood pressure increased, and these were more distinct in younger men and women. Hazard ratios also showed the same trends, and these trends were more apparent in younger men (hazard ratio [unit: 10-mm Hg increase] aged 40 to 49 years: systolic blood pressure 1.37 (range: 1.15 to 1.62); diastolic blood pressure 1.46 [range: 1.05 to 2.03]) than older ones (hazard ratio: aged 80 to 89 years: systolic blood pressure 1.09 [range: 1.05 to 1.13]and diastolic blood pressure 1.12 [range: 1.03 to 1.22]). Population-attributable fraction of hypertension was ≈20% when the normal category was used as a reference level and was 10% when we included the prehypertension group in the reference level. In conclusion, high blood pressure raised the risk of total mortality, and this trend was higher in the younger Japanese population. © 2008 American Heart Association, Inc.

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A prospective study of passive smoking and risk of diabetes in a cohort of workers

Hayashino Yasuaki, Fukuhara Shunichi, Okamura Tomonori, Yamato Hiroshi, Tanaka Hideo, Tanaka Taichiro, Kadowaki Takashi, Ueshima Hirotsugu

Diabetes Care 31 ( 4 ) 732 - 734 2008.04

ISSN 0149-5992

OBJECTIVE - We investigated the impact of active smoking and exposure to passive smoke on the risk of developing diabetes. RESEARCH DESIGN AND METHODS - Data were analyzed from a cohort of participants in the High-Risk and Population Strategy for Occupational Health Promotion Study (HIPOP-OHP) conducted in Japan from 1999 to 2004. Active and passive smoking status in the workplace was evaluated at baseline. RESULTS - Of 6,498 participants (20.9% women), a total of 229 diabetes cases were reported over a median 3.4 years of follow-up. In the workplace, compared with zero-exposure subjects, the multivariable-adjusted hazard ratios of developing diabetes were 1.81 (95% CI 1.06-3.08, P = 0.028) for present passive subjects and 1.99 (1.29-3.04, P = 0.002) for present active smokers. CONCLUSIONS - In this cohort, exposure to passive smoke in the workplace was associated with an increased risk of diabetes after adjustment for a large number of possible confounders. © 2008 by the American Diabetes Association.

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Relationship of elevated casual blood glucose level with coronary heart disease, cardiovascular disease and all-cause mortality in a representative sample of the Japanese population. NIPPON DATA80

Kadowaki S., Okamura T., Hozawa A., Kadowaki T., Kadota A., Murakami Y., Nakamura K., Saitoh S., Nakamura Y., Hayakawa T., Kita Y., Okayama A., Ueshima H.

Diabetologia 51 ( 4 ) 575 - 582 2008.04

ISSN 0012-186X

Aims/hypothesis: High fasting blood glucose is one of the well-known risk factors for CHD. However, in certain settings, patients cannot always be expected to fast. For example, community screenings for cardiovascular disease (CVD) risk factors in Japan are performed under non-fasting conditions to achieve high participation rates. Thus, we examined a representative cohort of the Japanese population (n=9,444, follow-up period 17.3 years) to clarify whether high casual blood glucose (CBG) can predict CVD mortality. Methods: We defined CBG groups as follows: high CBG≥11.1 mmol/l or participants with a history of diabetes mellitus; borderline high, 7.77≤CBG<11.1 mmol/l; higher normal, 5.22≤CBG<7.77 mmol/l); and lower normal, CBG<5.22 mmol/l. The multivariate-adjusted hazard ratios (HRs) for CHD, CVD and all-cause mortality were calculated. Results: The crude CHD mortality rate was 0.84 per 1,000 person-years. Age- and sex-adjusted HRs for CHD mortality were high among participants with CBG levels ≥7.77 mmol/l, regardless of time since last meal. Multivariate-adjusted HRs (95% CI) of CHD mortality in high and borderline high CBG groups were 2.62 (1.46-4.67) and 2.43 (1.29-4.58), respectively. Similar results were observed for both CVD and all-cause mortality. Even within the normal blood glucose range, each 1 mmol/l increase in CBG was associated with a statistically significant increase in the HR for CVD mortality (1.12, 95% CI 1.02-1.22). Population-attributable fractions of the combined groups of high and borderline high CBG for CHD, CVD and all-cause mortality were 12.0, 4.9 and 3.5%, respectively. Conclusions/interpretation: Increases in CBG, even within the normal range, predict CVD mortality. © 2007 Springer-Verlag.

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Difference in Carotid Intima-Media Thickness Between Korean and Japanese Men

Choo Jina, Ueshima Hirotsugu, Jang Yangsoo, Sutton-Tyrrell Kim, El-Saed Aiman, Kadowaki Takashi, Takamiya Tomoko, Okamura Tomonori, Ueno Yoshiki, Nakamura Yasuyuki, Sekikawa Akira, Curb J. David, Kuller Lewis H., Shin Chol

Annals of Epidemiology 18 ( 4 ) 310 - 315 2008.04

ISSN 1047-2797

Purpose: Koreans are recently at higher risk for coronary heart disease than are the Japanese. We aimed to evaluate levels of carotid intima-media thickness (IMT) and coronary risk factors in Korean and Japanese men in the post-World War II birth cohort. Methods: We conducted a population-based study of 352 randomly selected healthy men 40 to 49 years of age: 102 Koreans in Ansan City, Gyeonggi-do, Korea and 250 Japanese in Kusatsu City, Shiga, Japan. Imaging carotid IMT by ultrasonography and other procedures were standardized. Analyzing blood samples and reading carotid IMT were performed at the University of Pittsburgh. Results: Despite more favorable or similar features in coronary risk factors as compared to Japanese men, the Korean men had a higher crude IMT level than the Japanese men (mean ± standard error, 0.655 ± 0.008 mm vs 0.616 ± 0.005 mm, respectively, p < 0.0001). The difference in the levels of carotid IMT significantly remained after adjusting for metabolic and conventional risk factors (0.654 ± 0.008 mm vs. 0.616 ± 0.005 mm, respectively; p < 0.0001). Conclusions: Among men 40 to 49 years of age, Koreans had significantly higher levels of carotid IMT than the Japanese. Factors that underlie the different susceptibility to subclinical atherosclerosis need to be explored. © 2008 Elsevier Inc. All rights reserved.

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Effect of a 4-year workplace-based physical activity intervention program on the blood lipid profiles of participating employees

Naito Mariko, Nakayama Takeo, Okamura Tomonori, Miura Katsuyuki, Yanagita Masahiko, Fujieda Yoshiharu, Kinoshita Fujihisa, Naito Yoshihiko, Nakagawa Hideaki, Tanaka Taichiro, Ueshima Hirotsugu

Atherosclerosis 197 ( 2 ) 784 - 790 2008.04

ISSN 0021-9150

Individuals who are physically fit or engage in regular physical activity have a lower incidence of cardiovascular disease and risk of mortality. We conducted a large-scale controlled trial of interventions to decrease cardiovascular risk factors, during which we assessed the effect of a workplace-based intervention program, which was part of a population strategy for promoting long-term increases in physical activity, on the blood lipid profiles of participating employees. Data were collected from 2929 participants and this report presents the results of a survey conducted in five factories for the intervention group and five factories for the control group at baseline and year 5. The absolute/proportional changes in HDL-cholesterol were 2.7 mg/dL (4.8%) in the intervention group and -0.6 mg/dL (-1.0%) in the control group. The differences between the two groups in the change in serum levels of HDL-cholesterol were highly significant (p < 0.001) in each analysis of covariance, in which the number of cigarettes smoked was included or excluded. In the intervention group, the daily walking time increased significantly (p < 0.001) when compared between baseline and year 5, whereas no significant difference was observed in daily walking time in the control group over the identical period. Our results show that an intervention program promoting physical activity raises serum HDL-cholesterol levels of middle-aged employees. Increased awareness of the benefits of physical activity, using environmental rearrangement and health promotion campaigns, which especially target walking, may have contributed to a beneficial change in serum HDL-cholesterol levels in the participants. © 2007 Elsevier Ireland Ltd. All rights reserved.

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Lower levels of serum albumin and total cholesterol associated with decline in activities of daily living and excess mortality in a 12-year cohort study of elderly Japanese

Okamura Tomonori, Hayakawa Takehito, Hozawa Atsushi, Kadowaki Takashi, Murakami Yoshitaka, Kita Yoshikuni, Abbott Robert D., Okayama Akira, Ueshima Hirotsugu

Journal of the American Geriatrics Society 56 ( 3 ) 529 - 535 2008.03

ISSN 0002-8614

OBJECTIVES: To examine the association between levels of serum albumin and total cholesterol (TC) and risk of subsequent mortality and future decline in activities of daily living (ADLs) in elderly people. DESIGN: Population-based cohort study. SETTING: National Integrated Project for Prospective Observation of Non-Communicable Disease and Its Trends in the Aged, 1980. PARTICIPANTS: One thousand eight hundred forty-four Japanese individuals aged 60 to 74 randomly selected throughout Japan and followed for 12.4 years. MEASUREMENTS: Decline in ADLs and mortality. RESULTS: After adjusting for other covariates, the multivariable odds ratios (ORs) of impaired ADLs were highest in the lowest albumin quartile (≤40 g/L) for women. The multivariable OR of having a composite outcome of death or impaired ADL for the lowest albumin quartile compared with the highest was 1.56 (95% confidence interval (CI)=1.94-2.57) for men and 3.06 (95% CI=1.89-4.95) for women. Serum albumin was significantly and inversely associated with a composite outcome of death or impaired ADLs in the group below the median of TC in both sexes (multivariable OR for 1-g/L increase in serum albumin=0.88 for men (95% CI=0.79-0.97) and 0.79 for women (95% CI=0.72-0.87)), which was not significantly associated in the group with TC at or above the median. CONCLUSION: In the Japanese general population, low-normal serum albumin and TC levels are associated with loss of activity during old age, especially for women. © 2007, Copyright the Authors.

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Intima-media thickness of the carotid artery and the distribution of lipoprotein subclasses in men aged 40 to 49 years between whites in the United States and the Japanese in Japan for the ERA JUMP study

Sekikawa Akira, Ueshima Hirotsugu, Sutton-Tyrrell Kim, Kadowaki Takashi, El-Saed Aiman, Okamura Tomonori, Takamiya Tomoko, Ueno Yoshiki, Evans Rhobert W., Nakamura Yasuyuki, Edmundowicz Daniel, Kashiwagi Atsunori, Maegawa Hiroshi, Kuller Lewis H.

Metabolism: Clinical and Experimental 57 ( 2 ) 177 - 182 2008.02

ISSN 0026-0495

In men in the post-World War II birth cohort, that is, men aged 40 to 49 years, whites in the United States had significantly higher levels of intima-media thickness of the carotid arteries (IMT) than the Japanese in Japan (Electron-Beam Tomography and Risk Assessment Among Japanese and US Men in the Post World War II Birth Cohort [ERA JUMP] study). The difference remained after adjusting for traditional risk factors. Primary genetic effects are unlikely, given the degree to which IMT is increased in the Japanese who migrated to the United States. We investigated whether the differences in the distributions of lipoprotein subclasses explain the difference in IMT between the 2 populations. We examined population-based samples of 466 randomly selected men aged 40 to 49 years (215 whites from Allegheny County, Pennsylvania, and 241 Japanese from Kusatsu, Shiga, Japan). Lipoprotein subclasses were determined by nuclear magnetic resonance (NMR) spectroscopy. The whites had significantly higher levels of large very low-density lipoprotein particles and significantly lower levels of large high-density lipoprotein particles than the Japanese, whereas the 2 populations had similar levels of small low-density lipoprotein particles. The 2 populations had similar associations of IMT with NMR lipoproteins. Adjusting for NMR lipoproteins did not attenuate the significant difference in IMT between the 2 populations (0.671 ± 0.006 mm for the whites and 0.618 ± 0.006 mm for the Japanese, P = .01, mean ± SE). Differences in the distributions of NMR lipoproteins between the 2 populations did not explain the higher IMT in the whites. © 2008 Elsevier Inc. All rights reserved.

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Effects of the Y chromosome on cardiovascular risk factors in Japanese men

Hiura Yumiko, Fukushima Yasue, Kokubo Yoshihiro, Okamura Tomonori, Goto Yoichi, Nonogi Hiroshi, Takahashi Rie, Iwai Naoharu

Hypertension Research 31 ( 9 ) 1687 - 1694 2008

ISSN 0916-9636

Excess cardiovascular risk in men compared with women has been suggested to be partly explained by effects of the Y chromosome. However, inconsistent results have been reported on the Y chromosome's genetic influence on blood pressure and lipid levels. The purpose of the present study was to settle the question whether genetic variants of the Y chromosome influence cardiovascular risk factors using a large epidemiological cohort, the Suita study. Possible influences of the Y chromosome polymorphisms (Y chromosome Alu insertion polymorphism [YAP], M175 and SRY+465) on cardiovascular risk factors were assessed in 974 Japanese men. The frequency of the YAP(+) allele in our study sample was 0.31. The prevalence of hypertension tended to be higher in YAP(+) than in YAP(-) men, and this tendency was found to be stronger among men aged 65 years or older. Men with the YAP(+) genotype had higher levels of high density lipoprotein (HDL) cholesterol compared with those with the YAP(-) genotype, even after adjustment for age, body mass index, and daily ethanol and cigarette consumption (57.0±14.6 mg/dL vs. 54.2±14.2 mg/dL, nominal p=0.011, adjusted p=0.0062). However, these observed nominal associations disappeared after adjusting for multiple testing (Bonferroni). No association was detected between the YAP genotype and myocardial infarction. Similarly, none of the associations with M175 and SRY+465 attained significance when multiple testing was taken into account. In conclusion, Y chromosome polymorphisms (YAP, M175 and SRY+465) do not appear to be associated with cardiovascular risk factors in Japanese men. Studies using much larger sample sizes and/or additional independent samples will be required for definitive conclusions.

Relationships between family histories of stroke and of hypertension and stroke mortality

Kadota Aya, Okamura Tomonori, Hozawa Atsushi, Kadowaki Takashi, Murakami Yoshitaka, Hayakawa Takehito, Kita Yoshikuni, Okayama Akira, Nakamura Yasuyuki, Ueshima Hirotsugu

Hypertension Research 31 ( 8 ) 1525 - 1531 2008

ISSN 0916-9636

A family history of stroke seems to be related with increased risk of stroke although the relationship is not always significant. Increased risk of stroke is strongly associated with hypertension, which might be also associated with family history. However, investigations into the relationship between family history of hypertension and stroke mortality are scarce. We investigated whether a family history of stroke and that of hypertension evaluated using a simple questionnaire could predict stroke mortality in Japanese. We obtained parental histories of stroke and of hypertension from 8,037 randomly selected general Japanese without history of cardiovascular disease and followed them for 19 years. The multivariate adjusted hazard ratios (HRs) for total stroke mortality, intra-cerebral hemorrhage mortality and for cerebral infarction mortality according to family history were estimated using the Cox proportional hazards model. The prevalences of family histories of stroke and of hypertension were 20.6% and 31.1%, respectively. A family history of stroke was not related to total stroke mortality, intra-cerebral hemorrhage mortality or to cerebral infarction mortality. Meanwhile, a family history of hypertension was positively related to total stroke mortality among women aged less than 60 years and men aged 60 or more years (women: HR=3.41, 95% confidence interval [CI]: 1.49-7.81; men: HR=1.50, 95% CI: 1.00-2.24) even after adjustment for systolic blood pressure. In conclusion, a family history of stroke could not predict total stroke mortality. However, a family history of hypertension might predict an increased risk for total stroke.

Impact of metabolic syndrome components on the incidence of cardiovascular disease in a general urban Japanese population

Kokubo Yoshihiro, Okamura Tomonori, Yoshimasa Yasunao, Miyamoto Yoshihiro, Kawanishi Katsuyuki, Kotani Yasushi, Okayama Akira, Tomoike Hitonobu

Hypertension Research 31 ( 11 ) 2027 - 2035 2008

ISSN 0916-9636

Abdominal obesity is a prerequisite for some definitions of metabolic syndrome (MetS). We investigated the impact of MetS defined by two different criteria, which either did or did not require abdominal obesity as a prerequisite, on cardiovascular disease (CVD) incidence in an urban Japanese cohort study. We studied 5,332 Japanese (aged 30-79 years, without CVD at baseline), who completed a baseline survey (September 1989 to March 1994) and were followed up through December 2005. MetS was defined by the NCEP-ATPIII (modified by Asian obesity criteria) and the Japanese criteria. After 61,846 person-years of follow-up, we documented 317 CVD incidences. The MetS frequencies of the Japanese and of the modified NCEP-ATPIII criteria were 17.7% and 25.1% for men and 5.0% and 14.3% for women, respectively. The multivariate hazard ratios (HRs; 95% confidence intervals [CI]) of CVD incidence for MetS by the modified NCEP-ATPIII criteria were 1.75 (1.27-2.41) in men and 1.90 (1.31-2.77) in women, and those for MetS by the Japanese criteria were 1.34 (0.96-1.87) in men and 2.20 (1.31-3.68) in women. The multivariate HRs of CVD incidence for MetS for the Japanese and for the modified NCEP-ATPIII criteria were 2.92 (1.54-5.55) and 1.94 (0.98-3.82) in men under 60 years old, respectively. The CVD incidence risks increased according to the number of MetS components. The risks were similar among participants with the same number of MetS components, regardless of abdominal obesity. In conclusion, the number of MetS components (modified NCEP-ATPIII criteria) may be more strongly associated with CVD incidence than the abdominal obesity essential criteria (the Japanese criteria) in a general urban Japanese population.

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Low-risk profile for cardiovascular disease and mortality in Japanese

Yamamoto Takako, Nakamura Yasuyuki, Hozawa Atsushi, Okamura Tomonori, Kadowaki Takashi, Hayakawa Takehito, Murakami Yoshitaka, Kita Yoshikuni, Okayama Akira, Abbott Robert D., Ueshima Hirotsugu

Circulation Journal 72 ( 4 ) 545 - 550 2008

ISSN 1346-9843

Background: Some studies focusing on low-risk profiles for cardiovascular disease have been reported in Western countries. Yet, few reports have examined, with substantial longevity, the low-risk profile for cardiovascular disease in the Japanese population. This study examines whether having a favorable risk factor profile yields lower all-cause mortality and whether the proportion of those with a low-risk profile is larger in the Japanese population. Methods and Results: A total of 8,339 men and women aged 30-69 years without a history of cardiovascular diseases for 19 years, who had participated in the 1980 National Survey on Circulatory Disorders after being randomly selected from throughout Japan, were followed. Low risk was defined as having all of the following baseline characteristics: blood pressure (BP) <120/80 mmHg; no antihypertensive medication; serum cholesterol 160-240 mg/dl (4.14-6.22 mmol/L); no history of diabetes; and non-smoker. The long-term mortality of the low-risk group was compared with that of others using the Cox proportional hazard model. The prevalence of low risk was 9.4% of all participants. The multivariate-adjusted hazard ratios for low-risk individuals compared with others were as follows: 0.33 (95% confidence intervals (CI), 0.15-0.74) for cardiovascular disease and 0.63 (95% CI, 0.46-0.88) for all-cause mortality. The most attributable risk factor for all-cause mortality was high BP (≥120/80 mmHg). Conclusion Japanese individuals with favorable cardiovascular disease risk profiles had lower mortality from cardiovascular disease and all-causes than those without.

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The relationship between white blood cell count and risk of hypertension in populations with high prevalence of smoking

Okamura Tomonori, Watanabe Makoto

Hypertension Research 31 ( 7 ) 1279 - 1281 2008

ISSN 0916-9636

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Association of lipoprotein-associated phospholipase A2 with coronary calcification among American and Japanese men

El-Saed Aiman, Sekikawa Akira, Zaky Riad Wahid, Kadowaki Takashi, Takamiya Tomoko, Okamura Tomonori, Edmundowicz Daniel, Kita Yoshikuni, Kuller Lewis H., Ueshima Hirotsugu

Journal of Epidemiology 17 ( 6 ) 179 - 185 2007.12

ISSN 0917-5040

Background: We have previously reported that the prevalence of coronary artery calcification (CAC) was substantially lower among Japanese than American men despite a less favorable profile of many traditional risk factors in Japanese men. To determine whether lipoprotein-associated phospholipase A2 (Lp-PLA2) levels are related to the difference in the prevalence of CAC between the two populations. Methods: A total of 200 men aged 40-49 years were examined: 100 residents in Allegheny County, Pennsylvania, United States, and 100 residents in Kusatsu City, Shiga, Japan. Coronary calcium score (CCS) was evaluated by electron-beam tomography, Lp-PLA2 levels, nuclear magnetic resonance (NMR) lipoprotein subclasses, and other factors were assessed in 2001-2002. Results: Lp-PLA2 levels were higher among American than Japanese men (Mean ± standard deviation 301.7 ± 82.6 versus 275.9 ± 104.7 ng/mL, respectively, p=0.06). Among all Japanese men and those with low density lipoprotein (LDL) cholesterol ≥130 mg/dL, there was an inverse association of the prevalence of CCS>0 with the tertile groups of Lp-PLA2 levels (p=0.08 and p=0.03, respectively). American men did not have any association between CCS>0 with the tertile groups of Lp-PLA2 (p=0.62). Although Lp-PLA2 among both populations correlated positively with LDL and total cholesterol, American and Japanese men had different correlations with NMR lipoprotein subclasses. Reported high odds ratio for CCS>0 among American compared to Japanese men was not reduced after adjusting for Lp-PLA2 levels. Conclusion: Lp-PLA2 may have different mechanisms of action among American and Japanese men. Lp-PLA2 levels can not explain the observed CAC differences between the two populations. Copyright © 2007 by the Japan Epidemiological Association.

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Erratum

Hayashino Y., Fukuhara S., Suzukamo Y., Okamura T., Tanaka T., Ueshima H.

Acta Diabetologica 44 ( 4 ) 241 2007.12

ISSN 0940-5429

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Coronary artery calcification in Japanese men in Japan and Hawaii

Abbott Robert D., Ueshima Hirotsugu, Rodriguez Beatriz L., Kadowaki Takashi, Masaki Kamal H., Willcox Bradley J., Sekikawa Akira, Kuller Lewis H., Edmundowicz Daniel, Shin Chol, Kashiwagi Atsunori, Nakamura Yasuyuki, El-Saed Aiman, Okamura Tomonori, White Roger, Curb J. David

American Journal of Epidemiology 166 ( 11 ) 1280 - 1287 2007.12

ISSN 0002-9262

Explanations for the low prevalence of atherosclerosis in Japan versus the United States are often confounded with genetic variation. To help remove such confounding, the authors compared coronary artery calcification (CAC), a marker of subclinical atherosclerosis, between Japanese men in Japan and Japanese men in Hawaii. Findings were based on risk factors and CAC measured from 2001 to 2005 in 311 men in Japan and 300 men in Hawaii. Men were aged 40-50 years and without cardiovascular disease. After age adjustment, there was a threefold excess in the odds of prevalent CAC scores of ≥10 in Hawaii versus Japan (relative odds = 3.2, 95% confidence interval: 2.1, 4.9). Whereas men in Hawaii had a generally poorer risk factor profile, men in Japan were four times more likely to smoke cigarettes (49.5% vs. 12.7%, p < 0.001). In spite of marked risk factor differences between the samples, none of the risk factors explained the low amounts of CAC in Japan. After risk factor adjustment, the relative odds of CAC scores of ≥10 in Hawaii versus Japan was 4.0 (95% confidence interval: 2.2, 7.4). Further studies are needed to identify factors that protect against atherosclerosis in Japanese men in Japan. © The Author 2007. Published by the Johns Hopkins Bloomberg School of Public Health. All rights reserved.

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Joint impact of smoking and hypertension on cardiovascular disease and all-cause mortality in Japan

Hozawa Atsushi, Okamura Tomonori, Murakami Yoshitaka, Kadowaki Takashi, Nakamura Koshi, Hayakawa Takehito, Kita Yoshikuni, Nakamura Yasuyuki, Abbott Robert D., Okayama Akira, Ueshima Hirotsugu

Hypertension Research 30 ( 12 ) 1169 - 1175 2007.12

ISSN 0916-9636

Hypertension and smoking are major risk factors for death to cardiovascular disease (CVD). These attributions for CVD mortality should be higher in the countries where obesity-related conditions are uncommon. However, the joint effect of these risk factors on CVD and all-cause mortality have not been described. We followed a representative 8,912 Japanese men and women without a history of stroke and heart disease. Participants were categorized into 4 groups as follows: a group of individuals who neither smoked nor had hypertension (HT), a group of current smokers, a group with HT, and a group of current smokers with HT. We further calculated population-attributable fractions (PAF) of CVD and all-cause mortality based on relative hazards assessed by proportional hazard regression models. After 19 years of follow-up, we observed 313 and 291 CVID and 948 and 766 all-cause deaths for men and women, respectively. The PAF of CVD mortality due to smoking or HT were 35.1 % for men and 22.1 % for women. The PAF of CVID mortality was higher in participants <60 years of age (57.4% for men and 40.7% for women) vs. those who were older (26.3% for men and 18.1% for women). Aggressive aftempts to discourage smoking and to curb HT could yield large health benefits in Japan and throughout Asia, particularly for those aged <60 years. Efforts to warn about the adverse consequence of HT and smoking during adolescence and youth could yield the greatest health benefits, since positive behaviors adopted early are more easily continued into middle adulthood and later life.

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Is weak association between cigarette smoking and cardiovascular disease mortality observed in Japan explained by low total cholesterol? - NIPPON DATA80

Hozawa Atsushi, Okamura Tomonori, Kadowaki Takashi, Murakami Yoshitaka, Nakamura Koshi, Hayakawa Takehito, Kita Yoshikuni, Nakamura Yasuyuki, Okayama Akira, Ueshima Hirotsugu

International Journal of Epidemiology 36 ( 5 ) 1060 - 1067 2007.10

ISSN 0300-5771

Background: An international comparison has indicated that the association between smoking and cardiovascular disease (CVD) differs according to total cholesterol (TC) levels. However, little has been published about the relationship between smoking and CVD mortality among populations with various cholesterol levels. Methods: We calculated the adjusted relative hazard (RH) of smoking for CVD mortality among 8912 Japanese individuals without a history of stroke or heart disease, who were separated according to TC levels of ≥5.40, 4.81-5.39, 4.26-4.80 and <4.25 mmol/l into groups Q4, Q3, Q2 and Q1, respectively. The P-values for multiple interactions between TC and smoking status for CVD mortality were calculated using TC as a continuous variable, dichotomized smoking status (never vs current), and by including cross-product terms in the regression models. Results: After 19 years of follow-up, 313 men and 291 women died of CVD. The RH of CVD mortality among men who currently smoked compared with those who never smoked was increased with higher TC (RH = 2.36 in Q4) and decreased in those with lower TC (RH = 0.85 in Q1) (interaction, P = 0.01). The profiles for coronary heart disease (CHD) mortality and ischaemic CVD (composite endpoint of CHD and ischaemic stroke) in men and for ischaemic CVD mortality in women were identical. The interaction might be explained by a biological mechanism and by frailty of those who have never smoked with lower TC. Conclusions: Counteractive measures should be implemented against smoking targeted towards Japanese with elevated TC levels. © The Author 2007; all rights reserved.

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