Details of a Researcher - Okamura, Tomonori

Papers - Okamura, Tomonori

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Hypertension and medical expenses

Nakamura Koshi, Okamura Tomonori, Ueshima Hirotsugu

Nihon Naika Gakkai zasshi. The Journal of the Japanese Society of Internal Medicine 96 ( 1 ) 101 - 105 2007.01

ISSN 0021-5384

Relation of adult height with stroke mortality in Japan NIPPON DATA80

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

Stroke 38 ( 1 ) 22 - 26 2007.01

ISSN 0039-2499

BACKGROUND AND PURPOSE - The age-adjusted stroke mortality rate in Japan was the highest in the world from 1950 to the 1970s, but it started to dramatically decrease after 1965. In addition to improved management of high blood pressure, the increase in average height might also contribute to this reduction. The present study investigates whether height is an independent risk for stroke mortality in Japan. METHODS - Among participants of the National Survey on Cardiovascular Diseases in 1980 who were randomly selected from the Japanese population, we followed up 3969 and 4955 Japanese men and women without prior cardiovascular disease for a maximum of 19 years and observed 158 and 132 stroke deaths. RESULTS - Height was inversely correlated with age and with crude stroke mortality. The relationship was attenuated in men when we adjusted for age or other possible confounders (multivariate adjusted relative hazards of a 5-cm increase of height for stroke mortality: 0.92, 95% CI: 0.79 to 1.08). For women, the inverse relationship (relative hazard: 0.77: 95% CI: 0.64 to 0.91) remained after multivariate adjustment. These relationships persisted when we stratified participants by age. CONCLUSIONS - Height is inversely related to stroke mortality and the relationship is statistically significant among Japanese women. © 2007 American Heart Association, Inc.

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The relationship between serum total cholesterol and all-cause or cause-specific mortality in a 17.3-year study of a Japanese cohort

Okamura Tomonori, Tanaka Hideo, Miyamatsu Naomi, Hayakawa Takehito, Kadowaki Takashi, Kita Yoshikuni, Nakamura Yasuyuki, Okayama Akira, Ueshima Hirotsugu

Atherosclerosis 190 ( 1 ) 216 - 223 2007.01

ISSN 0021-9150

No study has shown a positive relationship between hypercholesterolemia and all-cause mortality in the Japanese population. Therefore, a cohort study of 17.3 years' duration was conducted on 9216 participants aged 30 years or older, selected randomly from throughout Japan. In both the lowest (<4.14 mmol/L, 160 mg/dl) and highest (≥6.71 mmol/L, 260 mg/dl) total cholesterol (TC) groups, there was a positive association between TC and risk of all-cause mortality (hazard ratio (HR) 1.19; 95% confidence interval (CI), 1.03-1.37 and 1.36 (95% CI, 1.05-1.77), respectively). The lowest TC group had an increased risk of liver disease (HR 3.03; 95% CI, 1.70-5.43), whereas the highest TC group had an increased risk of coronary heart disease (HR 3.81; 95% CI, 1.70-5.43). After exclusion of deaths due to liver disease during the entire follow-up period and all-cause deaths within the first 5 years of follow-up, the increased HR in the lowest TC group disappeared (HR 1.05; 95% CI, 0.89-1.24). Although the cut-off point seemed to be higher than that for Western populations, hypercholesterolemia was shown to be positively associated with all-cause mortality in Japan. © 2006 Elsevier Ireland Ltd. All rights reserved.

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Associations of obesity measures with metabolic risk factors in a community-based population in Japan

Nakamura Yasuyuki, Turin Tanvir C., Kita Yoshikuni, Tamaki Shinji, Tsujita Yasuyuki, Kadowaki Takashi, Murakami Yoshitaka, Okamura Tomonori, Ueshima Hirotsugu

Circulation Journal 71 ( 5 ) 776 - 781 2007

ISSN 1346-9843

Background: The association of obesity measures (ie, body mass index (BMI), waist circumference (WC) and waist-to hip ratio (WHR)) with metabolic risk factors in community-based populations has not been well studied. Methods and Results: In the present study 759 men and 1,255 women aged between 30 and 79 years, without histories of stroke or coronary heart diseases, were dichotomized at the medians of BMI-WHR, WC-WHR and BMI-WC. The accumulation of 4 metabolic risk factors (risk _ sum) were examined: high blood pressure (≥130/85 mmHg or on antihypertensive therapy); high triglycerides (≥170 mg/dl); low high-density lipoprotein-cholesterol (<40 mg/dl); and impaired glucose tolerance (hemoglobin A1c ≥5.6% or on antidiabetic therapy). BMI and WC correlated well in both men (r=0.871) and women (r=0.874). All 3 obesity measures related with the metabolic risk factors. The area under the receiver-operating characteristic curve for BMI, WC and WHR to predict the risk sum ≥2 for men was 0.683, 0.709, and 0.700, respectively, and 0.715, 0.739, and 0.746, respectively, for women. Conclusions: BMI may be used instead of WC if the latter is not available. When WC is measured, hip circumference also should be measured because the WHR may be the most valuable measure of obesity.

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Mortality risk attributable to atrial fibrillation in middle-aged and elderly people in the Japanese general population - Nineteen-year follow-up in NIPPON DATA80

Ohsawa Masaki, Okayama Akira, Okamura Tomonori, Itai Kazuyoshi, Nakamura Motoyuki, Tanno Kozo, Kato Karen, Yaegashi Yumi, Onoda Toshiyuki, Sakata Kiyomi, Ueshima Hirotsugu

Circulation Journal 71 ( 6 ) 814 - 819 2007

ISSN 1346-9843

Background: The extent to which atrial fibrillation (AF) contributes to mortality in the Japanese general population has not been clarified. Methods and Results: A randomly sampled general population from all over Japan (4,154 men, 5,329 women; age ≥30 years) was enrolled. Single electrocardiogram recordings were taken in the baseline survey. Stroke death, cardiovascular deaths and all-cause deaths during the subsequent 19 years were analyzed by the presence of AF at baseline. Cox's regression analysis was carried out to estimate the hazard ratios (HRs) of each cause of death attributable to AF after adjusting for other risk factors. Prevalence of AF was 0.64% in the study. The observed person-years were 162,980 among persons without AF and 699 among persons with AF. There were 1,919 deaths. Multivariate adjusted HRs for stroke death, cardiovascular death and all-cause death were 2.69, 2.76 and 1.88, respectively (p<0.05). These HRs were 14.7, 9.63 and 4.00 among persons aged 64 years or younger (p<0.05). Conclusion: AF affects stroke mortality, cardiovascular mortality and all-cause mortality in the Japanese general population. Careful attention should be paid to persons with AF in order to prevent future cardiovascular events.

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Discussion

Crabb David W., Yin Shih Jiun, Apte Minoti V., Emery Peter, Preedy Victor R., Peter Eriksson C. J., Salaspuro Mikko, Quertemont Etienne, Deitrich Richard A., Okamura Tomonori

63 - 68 2007

Effect of combined cardiovascular risk factors on individual and population medical expenditures - A 10-year cohort study of National Health Insurance in a Japanese population

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

Circulation Journal 71 ( 6 ) 807 - 813 2007

ISSN 1346-9843

Background: Although obesity is required for some criteria defining metabolic syndrome, clustering of other risk factors also indicates an increased risk of cardiovascular disease. Whether the relationship between cardiovascular risk factor clustering and medical expenditures differs with body mass index (BMI) requires investigation, especially in a population with a low prevalence of obesity such as that in Japan. Methods and Results: A 10-year cohort study of 4,478 Japanese National Health Insurance beneficiaries aged 40-69 years in a community between 1990 and 2001 was carried out in the present study. The clustering of cardiovascular risk factors showed a positive and graded relationship to personal medical expenditures in participants who are overweight (BMI ≥25.0) and normal weight (BMI <25.0). The individual medical expenditures per month were 1.7-fold higher for participants with 2 or 3 risk factors and overweight than for those without these factors (26,782 vs 15,377 Japanese yen). Differences in the geometric means were similarly significant after adjustment for other confounding factors. However, the excess medical expenditures by risk clustering of normal weight categories within the total medical expenditures were higher than those of overweight categories because more participants were of normal weight. Conclusions: Cardiovascular risk factor clustering and being overweight can be a useful predictor of medical expenditures in a Japanese population.

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Cardiovascular risk clustering with obesity

Okamura Tomonori

Circulation Journal 71 ( 10 ) 1667 2007

ISSN 1346-9843

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Discussion

Seitz Helmut K., Deitrich Richard A., Peter Eriksson C. J., Apte Minoti V., Preedy Victor R., Morris John B., Albano Emanuele, Worrall Simon, Emery Peter, Ren Jun, Crabb David W., Salaspuro Mikko, Quertemont Etienne, Thornalley Paul J., Rao Radhakrishna K., Aranda Agustin, Okamura Tomonori, Shukla Shivendra D., Niemelä Onni, Jamal Mostofa

40 - 51 2007

Discussion

Preedy Victor R., Peter Eriksson C. J., Morris John B., Salaspuro Mikko, Emery Peter, Thornalley Paul J., Seitz Helmut K., Rao Radhakrishna K., Worrall Simon, Apte Minoti V., Okamura Tomonori, Yin Shih Jiun

256 - 260 2007

White blood cell count and risk of all-cause and cardiovascular mortality in nationwide sample of Japanese - Results from the NIPPON DATA90

Tamakoshi Koji, Toyoshima Hideaki, Yatsuya Hiroshi, Matsushita Kunihiro, Okamura Tomonori, Hayakawa Takehito, Okayama Akira, Ueshima Hirotsugu

Circulation Journal 71 ( 4 ) 479 - 485 2007

ISSN 1346-9843

Background: The association of white blood cell (WBC) count with all-cause and cardiovascular disease (CVD) mortality were examined in the National Integrated Project for Prospective Observation of Non-communicable Disease and Its Trends in the Aged (NIPPON DATA) 90. Methods and Results: A total of 6,756 Japanese residents (2,773 men and 3,983 women) throughout Japan without a history of CVD were followed for 9.6 years. A Cox proportional hazards regression model was used to estimate the relative risk (RR) and 95% confidence interval (CI). We documented 576 deaths with 161 deaths from CVD. Overall, after adjusting for several confounders including age, sex, body mass index at baseline, smoking status, alcohol consumption, regular exercise, diastlic blood pressure, total cholesterol, high-density lipoprotein-cholesterol and hemoglobin A1c, a graded association between WBC count and higher risk of allcause mortality was observed (WBC of 9,000-10,000 cells/mm³ vs WBC of 4,000-4,900: RR =1.61, 95% CI: 1.07-2.40, p for trend=0.02). Elevated WBC count was almost significantly associated with high risk of CVD mortality (WBC of 9,000-10,000 vs WBC of 4,000-4,900: RR=1.79, 95% CI: 0.97-3.71). These associations strengthened among women. Stratified by smoking status, never-smokers with WBC counts of 9,000-10,000 had a 3.2 fold elevated risk for CVD death compared with those with WBC counts of 4,000-4,900. Conclusions: The WBC count may have potential as a predictor for all-cause mortality, particularly CVD mortality.

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Relation between sleep quality and quantity, quality of life, and risk of developing diabetes in healthy workers in Japan

Hayashino Yasuaki, Fukuhara Shunichi, Suzukamo Yoshimi, Okamura Tomonori, Tanaka Taichiro, Ueshima Hirotsugu

BMC Public Health 7 2007

Background. The effect of sleep on the risk of developing diabetes has not been explored in an Asian population. The objective of this study is to investigate the effect of self-reported sleep duration and sleep quality on the risk of developing diabetes in a prospective cohort in Japan. Methods. Data were analyzed from the cohort of participants in a High-risk and Population Strategy for Occupational Health Promotion Study (HIPOP-OHP), conducted in Japan from the year 1999 until 2004. A Cox proportional hazard model was used to evaluate the association between sleep duration or sleep quality and the risk of diabetes. Results. Of 6509 participants (26.1% of women, 19-69 years of age), a total of 230 type 2 diabetes cases were reported over a median 4.2 years of follow-up. For participants who often experienced difficulty in initiating sleep, the multivariate-adjusted hazard ratios for diabetes were 1.42 (95%CI, 1.05-1.91) in participants with a medium frequency of difficulty initiating sleep, and 1.61 (95%CI, 1.00-2.58) for those with a high frequency, with a statistically significant linear trend. Significant association was not observed in the association between difficulty of maintaining sleep or duration of sleep, and risk of diabetes. Conclusion. Medium and high frequencies of difficulty initiating sleep, but not difficulty in maintaining sleep or in sleep duration, are associated with higher risks of diabetes in relatively healthy Asian workers, even after adjusting for a large number of possible further factors. © 2007 Hayashino et al; licensee BioMed Central Ltd.

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Higher levels of adiponectin in American than in Japanese men despite obesity

Kadowaki Takashi, Sekikawa Akira, Okamura Tomonori, Takamiya Tomoko, Kashiwagi Atsunori, Zaky Wahid R., Maegawa Hiroshi, El-Saed Aiman, Nakamura Yasuyuki, Evans Rhobert W., Edmundowicz Daniel, Kita Yoshikuni, Kuller Lewis H., Ueshima Hirotsugu

Metabolism: Clinical and Experimental 55 ( 12 ) 1561 - 1563 2006.12

ISSN 0026-0495

Levels of adiponectin are inversely associated with obesity levels. We examined the levels of adiponectin in American (n = 98) and Japanese (n = 92) men aged 40 to 49 years. Contrary to our expectations, the American men had higher levels of adiponectin than the Japanese men (13.3 ± 5.8 vs 7.3 ± 4.2 (μg/mL) despite higher levels of obesity. Smaller areas of visceral adipose tissue in American than in Japanese men may have resulted in the higher levels of adiponectin. © 2006 Elsevier Inc. All rights reserved.

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Relationship between metabolic syndrome and Trp64Arg polymorphism of the β3-adrenergic receptor gene in a general sample

Tamaki Shinji, Nakamura Yasuyuki, Tabara Yasuharu, Okamura Tomonori, Kita Yoshikuni, Kadowaki Takashi, Tsujita Yasuyuki, Horie Minoru, Miki Tetsuro, Ueshima Hirotsugu

Hypertension Research 29 ( 11 ) 891 - 896 2006.11

ISSN 0916-9636

It has been reported that the β3-adrenergic receptor gene (ADRB3) is associated with abnormal metabolic risk factors. Therefore, we examined whether the Trp64Arg polymorphism of ADRB3 affects the occurrence of metabolic syndrome (MS). The participants were 2,395 subjects who underwent a medical examination in Shigaraki in Shiga, Japan. Among them, 1,416 subjects who gave informed consent for genetic analysis and were not receiving treatment for hypertension, diabetes, or hyperlipidemia were enrolled in this study. MS was diagnosed in 86 (16.0%) of 537 men, and 8 (0.9%) of 879 women. There was no significant relationship between ADRB3 polymorphism and the frequency of MS. Multiple logistic regression analysis including smoking, sex, and age as confounding factors showed no interaction between MS and ADRB3 polymorphism (odds ratio: 0.94; 95% confidence interval: 0.59-1.49; p=0.78). Subjects were also analyzed according to differences in the number of abnormal metabolic risk factors. However, there was no significant relationship between ADRB3 polymorphism and the number of such factors. In conclusion, in a general sample, the frequency of MS as 16.0% in men, and 0.9% in women. There was no relationship between ADRB3 polymorphism and MS.

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Medical costs of patients with hypertension and/or diabetes

Nakamura Koshi, Okamura Tomonori, Kanda Hideyuki, Hayakawa Takehito, Okayama Akira, Ueshima Hirotsugu

Journal of Hypertension 24 ( 11 ) 2305 - 2309 2006.11

ISSN 0263-6352

BACKGROUND AND METHODS: A cohort study investigating medical costs associated with the combination of hypertension and diabetes was conducted. The participants included 4535 community-dwelling Japanese individuals, aged 40-69 years, who were classified into the following four categories: 'Neither hypertension nor diabetes', 'Hypertension alone', 'Diabetes alone' or 'Both hypertension and diabetes'. Medical costs per person per month were compared among the four categories. RESULTS AND CONCLUSION: Of the study population, 1.3% had both hypertension and diabetes. During the 10-year follow-up period, participants with both hypertension and diabetes incurred higher medical costs, as compared with those without hypertension, diabetes or their combination, even after adjustment for other confounding factors. © 2006 Lippincott Williams & Wilkins, Inc.

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Body mass index and risk of stroke mortality among a random sample of Japanese adults

Oki Izumi, Nakamura Yosikazu, Okamura Tomonori, Okayama Akira, Hayakawa Takehito, Kita Yoshikuni, Ueshima Hirotsugu, Iimura Osamu, Omae Teruo, Ueda Kazuo, Yanagawa Hiroshi, Horibe Hiroshi, Kodama Kazunori, Kasagi Fumlyoshi, Tanihara Shinichi, Saito Shigeyuki, Sakata Kiyomi, Kakuno Fumihiko, Takeuchi Toshihiro, Hasebe Mitsuru, Kusano Fumitsugu, Kawamoto Takahisa, Minowa Masumi, Kawaminami Katsuhiko, Choudhury Sohel R., Kiyohara Yutaka, Iida Minoru, Hashimoto Tsutomu, Terao Atsushi, Sawai Koryo, Shibata Shigeo

Cerebrovascular Diseases 22 ( 5-6 ) 409 - 415 2006.10

ISSN 1015-9770

Background: The relationship between body mass index (BMI) and stroke mortality remains unclear. The aim of the present study was to elucidate the relationship between BMI and stroke death in a representative cohort of Japanese men and women. Methods: We analyzed a database of 9,526 men and women aged 30 years and older who were randomly selected throughout Japan in 1980. These individuals had no history of stroke and were followed for 19 years. Hazard ratios (HR) and their 95% confidence intervals (CI) of deaths due to total stroke, cerebral infarction, and intracerebral hemorrhage were examined using Cox's proportional hazards regression models of BMI levels. Results: A U-shaped association between BMI and cerebral infarction mortality was observed. Participants with the highest BMI category (BMI ≥ 30.0) showed a significantly highest HR for cerebral infarction (HR 2.46, 95% CI 1.01-5.99). The excess risk at the lower extreme of the BMI was confined to men. These associations did not change after excluding deaths occurring in the first 2 years of follow-up. Conclusions: In the Japanese general population, a U-shaped association between BMI and cerebral infarction mortality was found and the excess risk at the lower extreme of the BMI was confined to men. Copyright © 2006 S. Karger AG.

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Erratum

Nakamura Koshi, Okamura Tomonori, Hayakawa Takehito, Kadowaki Takashi, Kita Yoshikuni, Okayama Akira, Ueshima Hirotsugu

Hypertension Research 29 ( 10 ) 833 2006.10

ISSN 0916-9636

Continuation of smoking cessation and following weight change after intervention in a healthy population with high smoking prevalence

Kadowaki Takashi, Watanabe Makoto, Okayama Akira, Hishida Kayoko, Okamura Tomonori, Miyamatsu Naomi, Hayakawa Takehito, Kita Yoshikuni, Ueshima Hirotsugu

Journal of Occupational Health 48 ( 5 ) 402 - 406 2006.09

ISSN 1341-9145

Smoking prevalence among males is conspicuously high in Asian countries including Japan. There are few prospective intervention studies on the duration of smoking cessation within regions with a high prevalence of smokers, such as Asia. We investigated the extent to which subjects continued abstaining from smoking after receiving smoking cessation support provided for all smokers in an occupational setting, regardless of their willingness to quit smoking. The subjects were 251 male workers who were smokers and had received a smoking cessation intervention in 1997 in an occupational setting. Smoking cessation rates and body mass index (BMI) at 10, 18, 30, 42, 54, and 66 months after the initial intervention were confirmed during annual health check-ups. Those who quit smoking following the intervention and continuously abstained from smoking throughout the study period were separately examined for BMI. After five years, 10.6% of the smokers continued smoking cessation. Of the abstainers who quit following the intervention, the abstinence rate decreased in the first and second year, but it stabilized at approximately 45% after the third year. High nicotine dependence and a selfreported lack of willingness to quit smoking did not lower long-term abstinence rates. Abstainers initially gained 1.55 BMI on average, but decreased the weight gain to 0.96 BMI over six years. Introducing smoking cessation support without nicotine replacement therapy is an effective long-term strategy in a healthy population with a high smoking prevalence. Abstainers maintain their smoking cessation if they refrain from smoking for three years.

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Alcohol Consumption and Coronary Artery Calcium in Middle-Aged Japanese Men

Okamura Tomonori, Kadowaki Takashi, Sekikawa Akira, Murata Kiyoshi, Miyamatsu Naomi, Nakamura Yasuyuki, El-Saed Aiman, Kashiwagi Atsunori, Maegawa Hiroshi, Nishio Yoshihiko, Takamiya Tomoko, Kanda Hideyuki, Mitsunami Kenichi, Kita Yoshikuni, Edmundowicz Daniel, Tamaki Shinji, Tsujita Yasuyuki, Kuller Lewis H., Ueshima Hirotsugu

American Journal of Cardiology 98 ( 2 ) 141 - 144 2006.07

ISSN 0002-9149

Epidemiologic studies have investigated the relation between alcohol intake and coronary calcification, with controversial results. Furthermore, the influence of heavy drinking has not been well elucidated. In the present study, a random sample of community-based Japanese men aged 40 to 49 years without a history of cardiovascular disease (n = 245) were examined for coronary artery calcium (CAC) determined by electron-beam computed tomography and drinking status. There was a J-shaped association between alcohol intake and CAC. There was an increase of CAC in heavy drinkers (≥46 g/day), and participants who were drinking ≥69 g/day showed a significant increase in CAC compared with never drinkers after adjusting for other cardiovascular risk factors. © 2006 Elsevier Inc. All rights reserved.

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Japanese men have larger areas of visceral adipose tissue than Caucasian men in the same levels of waist circumference in a population-based study

Kadowaki T., Sekikawa A., Murata K., Maegawa H., Takamiya T., Okamura T., El-Saed A., Miyamatsu N., Edmundowicz D., Kita Y., Sutton-Tyrrell K., Kuller L. H., Ueshima H.

International Journal of Obesity 30 ( 7 ) 1163 - 1165 2006.07

ISSN 0307-0565

Visceral adipose tissue (VAT) is an independent risk factor for metabolic and cardiovascular disorders. There has been no study that demonstrated different abdominal fat distribution between Asian and Caucasian men. As the Japanese are less obese but more susceptible to metabolic disorders than Caucasians, they may have larger VAT than Caucasians at similar levels of obesity. We compared the abdominal fat distribution of the Japanese (n=239) and Caucasian-American (n=177) men aged 40-49 years in groups stratified by waist circumference in a population-based sample. We obtained computed tomography images and determined areas of VAT and subcutaneous adipose tissue (SAT). We calculated VAT to SAT ratio (VSR). The Japanese men had a larger VAT and VSR in each stratum, despite substantially less obesity overall. In multiethnic studies, difference in abdominal fat distribution should be considered in exploring factors related to obesity. © 2006 Nature Publishing Group All rights reserved.

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