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Dive into the research topics where Masato Nagai is active.

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Featured researches published by Masato Nagai.


Psychiatry and Clinical Neurosciences | 2016

Three-year trend survey of psychological distress, post-traumatic stress, and problem drinking among residents in the evacuation zone after the Fukushima Daiichi Nuclear Power Plant accident [The Fukushima Health Management Survey].

Misari Oe; Satoshi Fujii; Masaharu Maeda; Masato Nagai; Mayumi Harigane; Itaru Miura; Hirooki Yabe; Tetsuya Ohira; Hideto Takahashi; Yuriko Suzuki; Seiji Yasumura; Masafumi Abe

Prolonged periods of instability in terms of living environment can lead to a serious increase in mental health issues among disaster‐affected individuals. The aim of this study was to assess long‐term trends in mental health among adult residents in a nuclear‐disaster‐affected area.


British Journal of Nutrition | 2014

Low-carbohydrate diets and cardiovascular and total mortality in Japanese: a 29-year follow-up of NIPPON DATA80.

Yasuyuki Nakamura; Nagako Okuda; Tomonori Okamura; Aya Kadota; Naoko Miyagawa; Takehito Hayakawa; Yoshikuni Kita; Akira Fujiyoshi; Masato Nagai; Naoyuki Takashima; Takayoshi Ohkubo; Katsuyuki Miura; Akira Okayama; Hirotsugu Ueshima

Long-term safety of consuming low-carbohydrate diets (LCD) in Asian populations, whose carbohydrate intake is relatively high, is not known. In the present study, the association of LCD with CVD and total mortality was assessed using data obtained in the NIPPON DATA80 (National Integrated Project for Prospective Observation of Non-communicable Disease and Its Trends in the Aged 1980) during 29 years of follow-up. At baseline in 1980, data were collected from study participants aged ≥ 30 years from randomly selected areas in Japan. LCD scores were calculated based on the percentage of energy as carbohydrate, fat and protein, estimated by 3 d weighed food records. A total of 9200 participants (56% women, mean age 51 years) were followed up. During the follow-up, 1171 CVD deaths (52% in women) and 3443 total deaths (48% in women) occurred. The multivariable-adjusted hazard ratio (HR) for CVD mortality using the Cox model comparing the highest v. lowest deciles of LCD score was 0·60 (95% CI 0·38, 0·94; P(trend) = 0·021) for women and 0·78 (95% CI 0·58, 1·05; P(trend) = 0·079) for women and men combined; the HR for total mortality was 0·74 (95% CI 0·57, 0·95; P(trend) = 0·029) for women and 0·87 (95% CI 0·74, 1·02; P(trend) = 0·090) for women and men combined. None of the associations was statistically significant in men. No differential effects of animal-based and plant-fish-based LCD were observed. In conclusions, moderate diets lower in carbohydrate and higher in protein and fat are significantly inversely associated with CVD and total mortality in women.


Hypertension Research | 2015

Secular trends of the impact of overweight and obesity on hypertension in Japan, 1980–2010

Masato Nagai; Takayoshi Ohkubo; Yoshitaka Murakami; Naoyuki Takashima; Aya Kadota; Naoko Miyagawa; Yoshino Saito; Nobuo Nishi; Nagako Okuda; Yutaka Kiyohara; Hideaki Nakagawa; Yoshikazu Nakamura; Akira Fujiyoshi; Robert D. Abbott; Tomonori Okamura; Akira Okayama; Hirotsugu Ueshima; Katsuyuki Miura

The prevalence of overweight (body mass index (BMI)=25.0–29.9 kg m−2) and obesity (⩾30.0 kg m−2) has been increasing over the last several decades in Japan. We examined trends of the impact of overweight and obesity on hypertension (systolic/diastolic blood pressure ⩾140/90 mm Hg or antihypertensive drugs use) using four national surveys in Japan, from which the participants were randomly sampled from the entire population. Study participants aged 30–79 years were selected for each survey (10 370 in 1980, 8005 in 1990, 5327 in 2000 and 2547 in 2010). The results showed that the impact of overweight and obesity on hypertension had increased significantly (P=0.040 and 0.006 in men and women, respectively). From 1980 to 2010, the multivariable-adjusted odds ratios for hypertension, comparing overweight and obesity with normal weight (BMI =18.5–24.9 kg m−2), went from 1.94 (95% confidence intervals: 1.64, 2.28) to 2.82 (2.07, 3.83) in men, and from 2.37 (2.05, 2.73) to 3.48 (2.57, 4.72) in women. Most of the association was observed in overweight participants, as only 3% of the Japanese were obese. In addition to the relationship between excessive BMI and other adverse health conditions, the rise in the association with hypertension increases the urgency in addressing weight control. We need to address the overweight and obesity epidemic.


Journal of Atherosclerosis and Thrombosis | 2016

Serum Uric Acid and Mortality Form Cardiovascular Disease: EPOCH-JAPAN Study.

Wen Zhang; Hiroyasu Iso; Yoshitaka Murakami; Katsuyuki Miura; Masato Nagai; Daisuke Sugiyama; Hirotsugu Ueshima; Tomonori Okamura

AIM To investigate the relationship between serum uric acid levels and cardiovascular disease in Asians. METHODS We examined the above relationship using the data of Evidence for Cardiovascular Prevention from Observational Cohorts in Japan (EPOCH-JAPAN Study). The data of 36,313 subjects (15,628 men and 20,685 women aged 35-89 years without histories of stroke, coronary heart disease, or cancer at baseline) were used for the analyses. Sex-specific hazard ratios (HRs) of mortality from cardiovascular disease were estimated according to the quintiles of serum uric acid using Cox hazard models stratified by cohorts. RESULTS During 441,771 person-years of follow-up, we documented 1,288 cardiovascular deaths. A J- or U-shaped relationship between serum uric acid level and cardiovascular disease mortality was observed. Compared with the lowest quintile of serum uric acid levels, the highest quintile was associated with an increased cardiovascular disease mortality in men [HR: 1.28; 95% confidence interval (CI): 1.01-1.63] and women (HR: 1.51; 95% CI: 1.14-1.99). However, there was no significant association with mortality from stroke, coronary heart disease or heart failure in both men and women. CONCLUSION This large pooled analysis in Japan suggested a J- or U-shaped relationship between serum uric acid levels and cardiovascular mortality. The highest quintile of serum uric acid levels was associated with increased cardiovascular disease mortality in both Japanese men and women.


Asia-Pacific Journal of Public Health | 2017

Changes in Cardiovascular Risk Factors After the Great East Japan Earthquake: A Review of the Comprehensive Health Check in the Fukushima Health Management Survey

Tetsuya Ohira; Hironori Nakano; Masato Nagai; Yui Yumiya; Wen Zhang; Mayu Uemura; Akira Sakai; Shigeatsu Hashimoto

The Great East Japan Earthquake occurred on March 11, 2011, and was followed by a nuclear accident at the Fukushima Daiichi Nuclear Power Plant. The government ordered a mandatory evacuation from the high radioactive concentration area in Fukushima. This evacuation may have forced many evacuees to change specific aspects of their lifestyles such as diet and physical activity, which in turn may lead to future incidence of lifestyle diseases such as cardiovascular diseases (CVDs). To address this concern, the association between the evacuation and changes in CVD risk factors before and after the disaster was examined in the Fukushima Health Management Survey. In the present study, we reviewed the results of longitudinal studies in the Fukushima Health Management Survey. The proportion of overweight/obese people and those with hypertension, diabetes mellitus, dyslipidemia, liver dysfunction, atrial fibrillation, and polycythemia increased after the disaster. Furthermore, the evacuation was associated with an increase of these cardiovascular risk factors. Therefore, evacuees may be more disposed to CVDs such as myocardial infarction and stroke after the disaster. The prevention of future CVDs among evacuees from Fukushima requires ongoing preventive programs for obesity, hypertension, diabetes mellitus, and dyslipidemia, in collaboration with local governments and communities.


Internal Medicine | 2016

Hypo-high-density Lipoprotein Cholesterolemia Caused by Evacuation after the Fukushima Daiichi Nuclear Power Plant Accident: Results from the Fukushima Health Management Survey.

Hiroaki Satoh; Tetsuya Ohira; Masato Nagai; Mitsuaki Hosoya; Akira Sakai; Tsuyoshi Watanabe; Akira Ohtsuru; Yukihiko Kawasaki; Hitoshi Suzuki; Atsushi Takahashi; Gen Kobashi; Kotaro Ozasa; Seiji Yasumura; Shunichi Yamashita; Kenji Kamiya; Masafumi Abe

Objective The Great East Japan Earthquake and the Fukushima Daiichi nuclear disaster forced the evacuation of residents and led to many changes in the lifestyle of the evacuees. A comprehensive health check was implemented to support the prevention of lifestyle-related disease, and we analyzed changes in lipid metabolism before and after these disasters. Methods Subjects included Japanese men and women living near the Fukushima Daiichi nuclear power plant in Fukushima Prefecture. Annual health checkups, focusing on metabolic syndromes, were conducted for persons ≥40 years of age by the Heath Care Insures. Results A total of 27,486 subjects underwent a follow-up examination after the disaster, with a mean follow-up of 1.6 years. Following the disaster, the prevalence of hypo-high-density lipoprotein (HDL) cholesterolemia increased significantly from 6.0% to 7.2%. In the hypo-HDL cholesterolemia group, the body mass index (BMI), blood pressure, and LDL-C level increased significantly in men after the disaster. On the other hand, in the normal HDL-C level group, the BMI, blood pressure, glucose and lipid metabolism, and liver function were adversely affected. The decrease in HDL-C was significantly greater in evacuees than non-evacuees in the normal HDL-C level group. Furthermore, a multivariate logistic regression analysis showed that the evacuation was significantly associated with the incidence of hypo-HDL cholesterolemia. Conclusion This is the first study to evaluate how the evacuation affected the incidence of hypo-HDL cholesterolemia and led to an increase in cardiovascular disease. This information may be important in the follow-up and lifestyle change recommendations for evacuees.


BMJ Open | 2016

Predictors of severe psychological distress trajectory after nuclear disaster: evidence from the Fukushima Health Management Survey

Misari Oe; Masaharu Maeda; Masato Nagai; Seiji Yasumura; Hirooki Yabe; Yuriko Suzuki; Mayumi Harigane; Tetsuya Ohira; Masafumi Abe

Objectives The Fukushima Daiichi Nuclear Power Plant accident, which occurred after the Great East Japan Earthquake and Tsunami in March 2011, may have a considerable long-term impact on the lives of area residents. The aims of this study were to determine the trajectories of psychological distress using 3-year consecutive data, and to find predictive factors of severe distress that may also prove useful for public health intervention. Methods Data were obtained on 12 371 residents who were registered in the municipalities categorised as complete evacuation areas for 3 years after the disaster and who completed an assessment in each of the 3 years. Results Using group-based trajectory modelling, we identified four trajectory patterns distinguished by the levels of psychological distress, which gradually improved over time in all trajectories. Subjective sleep insufficiency, problem drinking, poor social support and perception of radiation risk 3 years after the accident were associated with the severity of psychological distress, according to the multivariate analysis. Conclusions The identified factors may be useful for community-based mental healthcare over the long term following a nuclear disaster.


Journal of Atherosclerosis and Thrombosis | 2017

Influence of Post-disaster Evacuation on Incidence of Metabolic Syndrome

Shigeatsu Hashimoto; Masato Nagai; Shingo Fukuma; Tetsuya Ohira; Mitsuaki Hosoya; Seiji Yasumura; Hiroaki Satoh; Hitoshi Suzuki; Akira Sakai; Akira Ohtsuru; Yukihiko Kawasaki; Atsushi Takahashi; Kotaro Ozasa; Gen Kobashi; Kenji Kamiya; Shunichi Yamashita; Shunichi Fukuhara; Hitoshi Ohto; Masafumi Abe

Aim: After the Great East Japan Earthquake, over 160,000 residents near the Fukushima Daiichi Nuclear Power Plant were forced to evacuate due to a nuclear accident. Health problems in these evacuees have since become major issues. We examined the association between evacuation and incidence of metabolic syndrome (METS) among residents in Fukushima. Methods: We conducted a cohort study among residents aged 40–74 years without METS at the time of the disaster in Fukushima. Among 20,269 residents who met the inclusion criteria before the disaster, 8,547 residents (3,697 men and 4,850 women; follow-up proportion: 42.2%) remained available for follow-up examinations after the disaster by the end of March 2013. The main outcome was incidence of METS, defined by guidelines from the Japanese committee, using data from the Comprehensive Health Check before and after the disaster. We divided participants by evacuation status and compared outcomes between groups. Using a logistic regression model, we estimated the odds ratio for incidence of METS, adjusting for potential confounders, age, gender, waist circumference, exercise habit, and alcohol consumption. Results: Incidence of METS was higher in evacuees (men 19.2%, women 6.6%) than in non-evacuees (men 11.0%, women 4.6%). Evacuees had higher body mass index, waist circumference, triglycerides, and fasting plasma glucose after the disaster than non-evacuees. We found a significant association between evacuation and incidence of METS (adjusted odds ratio 1.72, 95% confidence interval; 1.46–2.02). Conclusion: This is the first study to demonstrate that evacuation after a disaster is associated with increased incidence of METS.


Psychiatry and Clinical Neurosciences | 2016

Diagnostic interview study of the prevalence of depression among public employees engaged in long‐term relief work in Fukushima

Masaharu Maeda; Yukiko Ueda; Masato Nagai; Senta Fujii; Misari Oe

The Great East Japan Earthquake and in particular, the Fukushima Daiichi Nuclear Power Plant accident, have had a serious psychological impact on not only residents, but also relief workers in Fukushima. Although public employees work in highly stressful situations and play a very important role in long‐term relief, their psychiatric features have yet to be clarified. The two aims of this study were to identify the current prevalence rate of depression and post‐traumatic stress disorder among public employees working in the disaster area using diagnostic interviews, and to speculate on the psychosocial factors affecting their mental condition.


Journal of Epidemiology | 2017

Effect of evacuation on liver function after the Fukushima Daiichi Nuclear Power Plant accident: The Fukushima Health Management Survey.

Atsushi Takahashi; Tetsuya Ohira; Mitsuaki Hosoya; Seiji Yasumura; Masato Nagai; Hiromasa Ohira; Shigeatsu Hashimoto; Hiroaki Satoh; Akira Sakai; Akira Ohtsuru; Yukihiko Kawasaki; Hitoshi Suzuki; Gen Kobashi; Kotaro Ozasa; Shunichi Yamashita; Kenji Kamiya; Masafumi Abe

Background The Great East Japan Earthquake and subsequent Fukushima Daiichi Nuclear Power Plant accident caused residents to switch from their normal lives to lives focused on evacuation. We evaluated liver function before and after this disaster to elucidate the effects of evacuation on liver function. Methods This study was a longitudinal survey of 26,006 Japanese men and women living near the Fukushima Daiichi Nuclear Power Plant. This study was undertaken using data from annual health checkups conducted for persons aged 40–90 years between 2008 and 2010. Follow-up examinations were conducted from June 2011 to the end of March 2013, with a mean follow up of 1.6 years. Changes in liver function before and after the disaster were compared among evacuees and non-evacuees. We also assessed groups according to alcohol drinking status. Results The prevalence of liver dysfunction significantly increased in all participants from 16.4% before to 19.2% after the disaster. The incidence of liver dysfunction was significantly higher in evacuees than in non-evacuees. Multivariate logistic regression analysis showed that evacuation was significantly associated with liver dysfunction among residents. Conclusions This is the first study to show that evacuation due to the Fukushima Daiichi nuclear power plant disaster was associated with an increase in liver dysfunction.

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Tetsuya Ohira

Fukushima Medical University

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Seiji Yasumura

Fukushima Medical University

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Masafumi Abe

Fukushima Medical University

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Hideto Takahashi

Fukushima Medical University

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Masaharu Maeda

Fukushima Medical University

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Akira Sakai

Fukushima Medical University

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Hirooki Yabe

Fukushima Medical University

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Mayumi Harigane

Fukushima Medical University

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Hironori Nakano

Fukushima Medical University

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