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Objective To estimate the average treatment effect of working past the current retirement age on the health of Japanese men. Methods We used publicly available data from the National Survey of Japanese Elderly, extracting a sample of 1288 men who were 60 years or older. Survey respondents were followed-up for at most 15 years for the onset of four health outcomes: death, cognitive decline, stroke and diabetes. By using the propensity score method, we adjusted for the healthy worker effect by incorporating economic, sociodemographic and health data in the form of independent variables. By calculating the differences in times to a health outcome between those in employment and those not employed, we estimated the average treatment effects on health of being in paid work past retirement age. Findings Compared with those not employed, those in employment lived 1.91 years longer (95% confidence interval, CI: 0.70 to 3.11), had an additional 2.22 years (95% CI: 0.27 to 4.17) before experiencing cognitive decline, and had a longer period before the onset of diabetes and stroke of 6.05 years (95% CI: 4.44 to 7.65) and 3.35 years (95% CI: 1.42 to 5.28), respectively. We also observed differences between employees and the self-employed: the self-employed had longer life expectancies than employees. In terms of years to onset of diabetes or stroke, however, we only observed significant benefits to health of being an employee but not self-employed. Conclusion Our study found that being in employment past the current age of retirement had a positive impact on health. [ABSTRACT FROM AUTHOR]

Background The relative and absolute risks of outcomes other than all-cause death (ACD) attributable to atrial fibrillation (AF) stratified age have not been sufficiently investigated. Methods A prospective study of 23,634 community dwellers aged 40 years or older without organic cardiovascular disease (AF = 335, non-AF = 23,299) was conducted. Multivariate-adjusted rates, rate ratios (RRs) and excess deaths (EDs) for ACD, cardiovascular death (CVD) and non-cardiovascular death (non-CVD), and sex- and age-adjusted RR and ED in middle-aged (40 to 69) and elderly (70 years or older) for ACD, CVD, non-CVD, sudden cardiac death (SCD), stroke-related death (Str-D), neoplasm-related death (NPD), and infection-related death (IFD) attributable to AF were estimated using Poisson regression. Results Multivariate-adjusted analysis revealed that AF significantly increased the risk of ACD (RR [95% confidence interval]:1.70 [1.23-2.95]) and CVD (3.86 [2.38-6.27]), but not non-CVD. Age-stratified analysis revealed that AF increased the risk of Str-D in middle-aged (14.5 [4.77-44.3]) and elderly individuals (4.92 [1.91-12.7]), SCD in elderly individuals (3.21 [1.37-7.51]), and might increase the risk of IFD in elderly individuals (2.02 [0.80-4.65], p = 0.098). The RR of CVD was higher in middle-aged versus elderly individuals (RRs, 6.19 vs. 3.57) but the absolute risk difference was larger in elderly individuals (EDs: 7.6 vs. 3.0 per 1000 person-years). Conclusions Larger absolute risk differences for ACD and CVD attributable to AF among elderly people indicate that the absolute burden of AF is higher in elderly versus middle-aged people despite the relatively small RR. [ABSTRACT FROM AUTHOR]

Background: We previously reported that egg consumption was related to age-adjusted serum total cholesterol (TCH), and all-cause mortality in the 1-2-eggs/wk group was significantly lower than that in the 1-egg/d group in women, whereas no such relations were noted in men, using 14 year follow-up of NIPPON DATA80. Re-evaluation of these relations in a different cohort is needed. Methods: We analyzed the relations of egg consumption to serum total cholesterol (TCH) and cause-specific and all-cause mortality by using the NIPPON DATA90 database with a 15-year follow-up. At the baseline in 1990, a nutritional survey was performed by using the food-frequency method, and data were collected on study participants, ages 30 years and over, from randomly selected areas in Japan. We followed 4,799 female participants without history of stroke or myocardial infarction (mean age 52.8 y) for 15 years. Results: The participants were categorized into 5 egg consumption groups on the basis of their responses to a questionnaire (seldom, 1-2/wk, 1/2 d, 1/d, and ≥2/d). There were 218, 1507, 1622, 1409, and 43 women in each of the 5 groups, respectively. Age-adjusted TCH was not related to egg consumption (206.4, 206.3, 207.0, 207.7, and 203.8 mg/dL in the 5 egg consumption categories, respectively, P=0.737, analysis of covariance). There were 199 cardiovascular disease (CVD), 221 cancer, and 642 all-cause mortality during follow-up. Cox analysis, adjusted for confounding factors, found that all-cause and cancer mortality in the ≥2/d group were significantly higher than that in the 1-egg/d group (HR in the ≥2/d vs the 1-egg/d group: all-cause, 1.88 [95%CI: 1.12-3.16]; cancer, 2.77 [1.32-5.80]), and that cancer mortality in the 1-2-eggs/wk group was significantly lower than that in the 1-egg/d group (0.70 [0.50-0.99]). Egg consumption was not associated with CVD mortality. Conclusions: Loss of the relation of egg consumption to TCH might be due to that hypercholesterolemic individuals avoided eating eggs. Positive association of egg consumption with cancer and all-cause mortality needs further evaluation, and it may indicate that limiting egg consumption has some health benefits, at least in women in Japan. [ABSTRACT FROM AUTHOR]

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 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 Conclusions Counteractive measures should be implemented against smoking targeted towards Japanese with elevated TC levels. [ABSTRACT FROM AUTHOR]

We investigated the relationship between smoking and the risk of nonnormal (≤ 0.99) ankle-brachial index (ABI) at rest and after ankle plantar flexion exercise in healthy male community dwellers. A cross-sectional study was performed including 228 Japanese men aged 40 to 64 years without a history of cardiovascular diseases. Participants were classified as never, ex-, and current smokers. We estimated the multivariate-adjusted odds ratios (ORs) for nonnormal ABI of ex- and current smokers in relation to never smokers after adjusting for age and other confounding factors. At rest, the prevalence of nonnormal ABI was not significantly different by smoking status. After exercise, the prevalence of nonnormal ABI increased from 1.8% to 11.5% in ex-smokers and from 3.8% to 17.0% in current smokers, while the prevalence did not significantly change in never smokers. The multivariate-adjusted OR for nonnormal ABI after ankle plantar flexion exercise, in relation to never smokers, was 3.85 (95% confidence interval [CI]: 0.79-18.9) for ex-smokers and 6.97 (95% CI: 1.32-36.7) for current smokers. Our results suggest that ABI after ankle plantar flexion exercise is useful for early detection of subclinical peripheral artery ischemia in male smokers without typical symptoms. [ABSTRACT FROM AUTHOR]

Aims: Although previous reports suggest that an elevated endogenous erythropoietin (EPO) level is associated with worse clinical outcomes in chronic heart failure (HF) patients, the prognostic implication of EPO in patients with acute decompensated HF (ADHF) and underlying mechanisms of the high EPO level in severe HF patients who have a poor prognosis remain unclear. Methods and results: We examined 539 consecutive ADHF patients with EPO measurement on admission from our registry. During a median follow-up period of 329 days, a higher EPO level on admission was independently associated with worse clinical outcomes [hazard ratio (HR) 1.25, 95% confidence interval (CI) 1.06-1.48, P = 0.008], and haemoglobin level was the strongest determinant of EPO level (P < 0.001), whereas estimated glomerular filtration rate (eGFR) was not significant in multivariate regression analysis. In the anaemic subgroup of 318 patients, a higher EPO level than expected on the basis of their haemoglobin level was related to increased adverse events (HR 1.63, 95% CI 1.05-2.49, P = 0.028). Moreover, estimated plasma volume excess rate was positively associated with EPO level (P = 0.003), and anaemic patients with a higher than expected EPO level tended to have a higher estimated plasma volume excess rate and plasma lactate level, and lower systemic oxygen saturation level with the preservation of the reticulocyte production index than those with a lower than expected EPO level. Conclusion: A high EPO level predicts long-term worse clinical outcomes in ADHF patients, independent of anaemia and impaired renal function. Anaemia and hypoxia due to severe congestion may synergistically contribute to a high EPO level in high-risk HF patients. [ABSTRACT FROM AUTHOR]

Background: The Seven Countries Study in the 1960s showed very low mortality from coronary heart disease (CHD) in Japan, which was attributed to very low levels of total cholesterol. Studies of migrant Japanese to the USA in the 1970s documented increase in CHD rates, thus CHD mortality in Japan was expected to increase as their lifestyle became Westernized, yet CHD mortality has continued to decline since 1970. This study describes trends in CHD mortality and its risk factors since 1980 in Japan, contrasting those in other selected developed countries.Methods: We selected Australia, Canada, France, Japan, Spain, Sweden, the UK and the USA. CHD mortality between 1980 and 2007 was obtained from WHO Statistical Information System. National data on traditional risk factors during the same period were obtained from literature and national surveys.Results: Age-adjusted CHD mortality continuously declined between 1980 and 2007 in all these countries. The decline was accompanied by a constant fall in total cholesterol except Japan where total cholesterol continuously rose. In the birth cohort of individuals currently aged 50-69 years, levels of total cholesterol have been higher in Japan than in the USA, yet CHD mortality in Japan remained the lowest: >67% lower in men and > 75% lower in women compared with the USA. The direction and magnitude of changes in other risk factors were generally similar between Japan and the other countries.Conclusions: Decline in CHD mortality despite a continuous rise in total cholesterol is unique. The observation may suggest some protective factors unique to Japanese. [ABSTRACT FROM AUTHOR]

Objective To determine whether serum concentrations of long chain n-3 polyunsaturated fatty acids (LCn3PUFAs) contribute to the difference in the incidence rate of coronary artery calcification (CAC) between Japanese men in Japan and white men in the USA. Methods In a population based, prospective cohort study, 214 Japanese men and 152 white men aged 40-49 years at baseline (2002-2006) with coronary calcium score (CCS)=0 were re-examined for CAC in 2007-2010. Among these, 175 Japanese men and 113 white men participated in the follow-up exam. Incident cases were defined as participants with CCS=10 at follow-up. A relative risk regression analysis was used to model the incidence rate ratio between the Japanese and white men. The incidence rate ratio was first adjusted for potential confounders at baseline and then further adjusted for serum LCn3PUFAs at baseline. Results Mean (SD) serum percentage of LCn3PUFA was >100% higher in Japanese men than in white men (9.08 (2.49) vs 3.84 (1.79), respectively, p<0.01). Japanese men had a significantly lower incidence rate of CAC compared to white men (0.9 vs 2.9/100 personyears, respectively, p<0.01). The incidence rate ratio of CAC taking follow-up time into account between Japanese and white men was 0.321 (95% CI 0.150 to 0.690; p<0.01). After adjusting for age, systolic blood pressure, low density lipoprotein cholesterol, diabetes, and other potential confounders, the ratio remained significant (0.262, 95% CI 0.094 to 0.731; p=0.01). After further adjusting for LCn3PUFAs, however, the ratio was attenuated and became non-significant (0.376, 95% CI 0.090 to 1.572; p=0.18). Conclusions LCn3PUFAs significantly contributed to the difference in the incidence of CAC between Japanese and white men. [ABSTRACT FROM AUTHOR]

The United States has a higher prevalence of metabolic syndrome (MS) and cardiovascular disease (CVD) mortality than Japan, but it is unknown how much of the difference in MS accounts for the mortality difference. The aim of this study was to examine the impact of MS on the excess CVD mortality in the United States compared with that in Japan. Data from the United States Third National Health and Nutrition Examination Survey (NHANES III; n = 12,561) and the Japanese National Integrated Project for Prospective Observation of Noncommunicable Disease and Its Trends in Aged (NIPPON DATA; n = 7,453) were analyzed. MS was defined as ≥3 of 5 risk factors (obesity, high blood pressure, decreased high-density lipoprotein cholesterol, elevated glycosylated hemoglobin, and elevated triglycerides). The results show that after a median of 13.8 years of follow-up in the United States, 1,683 patients died from CVD (11.75 per 1,000 person-years), and after a median of 15 years of follow-up in Japan, 369 patients died from CVD (3.56 per 1,000 person-years). The ageadjusted prevalence of MS was 26.7% in the United States and 19.3% in Japan. Of 5 MS factors, obesity, high blood pressure, elevated triglycerides, and glycosylated hemoglobin in the United States, and high blood pressure and elevated glycosylated hemoglobin in Japan were significant risk factors for CVD mortality. Estimates of 13.3% and 44% of the excess CVD mortality for the United States could be explained by the higher prevalence of MS and MS plus baseline CVD history than in Japan. In conclusion, the present study is the first to quantitatively demonstrate that MS and MS plus baseline CVD history may significantly contribute to the explanation of excess CVD mortality in the United States compared with Japan. [ABSTRACT FROM AUTHOR]

Background: Cigarette smoking is a risk factor of coronary heart disease. Vascular calcification such as coronary artery calcium (CAC) and aortic calcium (AC) is associated with coronary heart disease. The authors hypothesised that cigarette smoking is associated with coronary artery and aortic calcifications in Japanese and Koreans with high smoking prevalence. Methods: Random samples from populations of 313 Japanese and 302 Korean men aged 40-49 years were examined for calcification of the coronary artery and aorta using electron beam CT. CAC and AC were quantified using the Agatston score. The authors examined the associations of cigarette smoking with CAC and AC after adjusting for conventional risk factors and alcohol consumption. Current and past smokers were combined and categorised into two groups using median pack-years as a cut-off point in each of Japanese and Koreans. The never-smoker group was used as a reference for the multiple logistic regression analyses. Results: The ORs of CAC (score ≥10) for smokers with higher pack-years were 2.9 in Japanese (p<0.05) and 1.3 in Koreans (non-significant) compared with neversmokers. The ORs of AC (score ≥100) for smokers with higher pack-years were 10.4 in Japanese (p<0.05) and 3.6 in Koreans (p<0.05). Conclusion: Cigarette smoking with higher pack-years is significantly associated with CAC and AC in Japanese men, while cigarette smoking with higher pack-years is significantly associated with AC but not significantly with CAC in Korean men. [ABSTRACT FROM AUTHOR]

Objective. Despite considerable study, the relevance of leptin and adiponectin for atherosclerosis development is still unsettled. We investigated relations of serum leptin and adiponectin to serum C-reactive protein (CRP), using the INTERLIPID dataset on Japanese emigrants living in Hawaii and Japanese in Japan. Design and Methods. Serumleptin, adiponectin, and CRP were measured by standardized methods in men and women of ages 40 to 59 years from two population samples, one Japanese-American in Hawaii (83 men, 89 women) and the other Japanese in central Japan (111 men, 104 women). Participants with CRP >10mg/L were excluded. Results. Sex-specific multiple linear regression analyses, with log-transformed leptin and adiponectin (log-leptin, log-adipo), site (Hawaii = 1, Japan = 0), SBP, HbA1c, smoking (cigarettes/day), and physical activity index score of the Framingham Offspring Study as covariates, showed that log-leptin directly related and log-adipo inversely related to log-CRP for both sexes (Ps < 0.05 to <0.01). Addition to the model of BMI and interaction terms (BMI × log-leptin, BMI × log-adipo, SITE × log-leptin, SITE × logadipo) resulted in disappearance of statistical significance except for direct relation of log-leptin to log-CRP in men (P = 0.006). Conclusions. Leptin directly related to CRP independent of BMI and other confounding factors in men but not in women. [ABSTRACT FROM AUTHOR]

This study examines the differences in circulating levels of cytokines among Japanese in Japan (JJ), Japanese Americans (JA), and whites and their associations with obesity and marine n-3 fatty acids (FA) in a cross-sectional population-based study of 297 men aged 40–49 (100 JJ, 99 whites, and 98 JA). Experimental studies show that cytokines are associated with obesity positively and marine n-3 FA inversely. Serum interleukin-1α (IL-1α), IL-1 receptor agonist (IL-1ra), IL-4, IL-8, IL-10, inducible protein-10 (IP-10), tumor necrosis factor-α (TNF-α), monocyte chemoattractant protein-1 (MCP-1), and marine n-3 FA were determined. Body mass index (BMI), waist circumference, and computed tomography-measured visceral and subcutaneous adipose tissues were determined. The JJ had significantly lower levels of IL-1α, IL-4, IL-8, MCP-1, and TNF-α than whites and JA. Whites and JA had similar levels of IL-1α, IL-4, and IL-8 whereas whites had significantly higher levels of MCP-1 and TNF-α than JA. The JJ were least obese (BMI (kg/m2), mean ± standard deviation) 23.6 ± 2.8, 27.9 ± 4.6, and 27.9 ± 4.5 for JJ, whites, and JA, respectively. The JJ had marine n-3 FA about 100% higher than whites and JA (serum marine n-3 FA (%), median (interquartile range) 8.79 (7.41, 11.16), 3.47 (2.63, 4.83), and 4.44 (3.33, 6.01) for JJ, whites, and JA, respectively). Generally cytokines had weak and nonsignificant associations with indices of obesity and nonsignificant associations with marine n-3 FA. BMI had significant inverse associations with IL-1α, IL-4, and IL-8 in JA (P< 0.05). Marine n-3 FA had marginally significant inverse associations with IL-8 in JJ (P= 0.055) and TNF-α in whites (P= 0.076). The JJ had lower levels of many cytokines than whites and JA. Generally cytokines had weak and nonsignificant associations with indices of obesity and marine n-3 FA. Further investigation is needed to determine why JJ had lower circulating levels of cytokines. [ABSTRACT FROM AUTHOR]

Coronary heart disease incidence and mortality remain very low in Japan despite major dietary changes and increases in risk factors that should have resulted in a substantial increase in coronary heart disease rates (Japanese paradox). Primary genetic effects are unlikely, given the substantial increase in coronary heart disease in Japanese migrating to the United States. For men aged 40–49 years, levels of total cholesterol and blood pressure have been similar in Japan and the United States throughout their lifetimes. The authors tested the hypothesis that levels of subclinical atherosclerosis, coronary artery calcification, and intima-media thickness of the carotid artery in men aged 40–49 years are similar in Japan and the United States. They conducted a population-based study of 493 randomly selected men: 250 in Kusatsu City, Shiga, Japan, and 243 White men in Allegheny County, Pennsylvania, in 2002–2005. Compared with the Whites, the Japanese had a less favorable profile regarding many risk factors. The prevalence ratio for the presence of a coronary calcium score of ≥10 for the Japanese compared with the Whites was 0.52 (95% confidence interval: 0.35, 0.76). Mean intima-media thickness was significantly lower in the Japanese (0.616 mm (standard error, 0.005) vs. 0.672 (standard error, 0.005) mm, p < 0.01). Both associations remained significant after adjusting for risk factors. The findings warrant further investigations. [ABSTRACT FROM AUTHOR]

Aims: The association between carbohydrate intake and cardiovascular disease (CVD) risk has been investigated; however, it remains unclear. Carbohydrate quality is considered to be more important than its amount. Carbohydrate consists of fiber and available carbohydrate which includes starch and sugar. The aim of this study was to examine the relationship of each of carbohydrate, available carbohydrate, starch and fiber intake to the long-term CVD mortality risk in Japanese population. We also examined the relationship of the ratios of carbohydrate, available carbohydrate or starch-to-fiber to CVD risk. Methods: We prospectively followed 8,925 participants (3,916 men and 5,009 women) aged 30-79 years without CVD who participated in the National Nutrition Survey in 1980 from 300 randomly selected areas in Japan. The participants were followed for 24 years. To identify the cause of death, the National Vital Statistics database of Japan was used. Food intake survey using weighed food records over three days in each household was conducted. The nutrient intake reported for each household was proportionally allocated to each household member according to the mean consumption rate by age and sex in 1995. Ratios of carbohydrate, available carbohydrate or starch intake (g/day) divided by dietary fiber intake (g/day) were also calculated. Cox proportional hazards models were used to estimate multivariable-adjusted hazard ratios (HRs) for CVD mortality by sex-specific quartiles of fiber (g/1000kcal), carbohydrate (%kcal), available carbohydrate (%kcal), starch (%kcal) and their ratios. HRs were adjusted for age, sex, lifestyle factors (smoking status, drinking status, BMI, medication of hypertension, past history of diabetes mellitus), and dietary factors (intakes of sodium, saturated fatty acids and long-chain n-3 polyunsaturated fatty acids). Results: During 24-years of follow up, 823 CVD deaths were observed (419 men and 404 women). Adjusted HR for CVD mortality was lower in the highest quartile (Q4) of fiber intake (0.71, 95%CI: 0.57-0.89, P-trend 0.003) compared with the lowest (Q1). However, carbohydrate, available carbohydrate and starch intake were not associated with CVD mortality (Adjusted HR for Q4 compared with Q1: 1.00, 95%CI: 0.76-1.32, P-trend 0.875; 1.07, 0.82-1.40, 0.757; 0.92, 0.71-1.20, 0.619; respectively). The ratios of carbohydrate, available carbohydrate or starch-to-fiber were all positively associated with CVD mortality (Adjusted HR for Q4 compared with Q1: 1.40, 95%CI: 1.13-1.73, P-trend 0.003; 1.33, 1.08-1.64, 0.006; 1.23, 0.99-1.52, 0.032; respectively). Conclusions: Dietary fiber intake was inversely related to long-term CVD mortality risk in Japanese. The ratios of carbohydrate, available carbohydrate or starch-to-fiber were positively associated with long-term CVD mortality risk; they might be useful indexes to predict future CVD risk. [ABSTRACT FROM AUTHOR]

Objective: Obesity is an established risk factor for hypertension (HT), but it is still controversial which obesity-related indicator is superior in predictability. This study compared the predictability among three indicators, body mass index (BMI), waist circumference (WC) and waist-to-height ratio (WHtR), in the population-based prospective cohort study of Japan, the Suita study. Methods: Participants who had no HT at baseline (1,591 men and 1,973 women) aged 30-84 years were included in this study. The Cox proportional hazard model was used to estimate hazard ratios (HRs) of each indicator for incident HT with the adjustment for age, cigarette smoking and alcohol drinking. Harrell's C statistics were also estimated for comparison of indicators' accuracy. Results: During median follow-up of 7.2 years, 1,325 participants (640 men and 685 women) developed HT. HR (95% CI) of BMI, WC and WHtR for incident HT corresponding to a 1 SD increase was 1.25 (1.15-1.35), 1.21 (1.12-1.31) and 1.23 (1.14-1.34) in men while 1.32 (1.22-1.42), 1.27 (1.18-1.37) and 1.32 (1.21-1.44) in women, respectively. Also, C-statistic (95% CI) of BMI, WC and WHtR was 0.64 (0.62-0.66), 0.63 (0.61-0.65) and 0.63 (0.61-0.66) in men while 0.69 (0.67-0.71), 0.69 (0.67-0.71) and 0.69 (0.67-0.71) in women, respectively. Using 95% CI of each C-statistics, there were no statistical differences among three indicators in both men and women. Conclusion: In this study, we showed that all three indicators (BMI, WC and WHtR) were estimated similarly to predict the risk of developing HT in both Japanese men and women. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Background Fatigue is one of the most common symptoms encountered in medical practice. However, little is known about the causal relationship between change in lifestyle and fatigue. Aim To help prevent fatigue-related disorders, we investigated the association between changes in lifestyle and fatigue among employees. Methods We studied data sets from the High-risk and Population Strategy for Occupational Health Promotion study for employees at 10 workplaces in Japan. The baseline survey was done in 1999 and the follow-up survey in 2003 via a questionnaire which examined lifestyle and fatigue variables using the vitality domain scale of the SF-36 Health Survey. The lifestyle factors focused on were diet, smoking and alcohol habits and working conditions. Four-year changes in lifestyle that predicted the vitality domain score in the follow-up survey were examined by analysis of covariance Results Of the 6284 participants in the baseline survey, 4507 replied to the follow-up survey, of whom 3498, with a mean age of 37 (SD 18) years, returned valid responses. A low vitality score at follow-up was predicted by a change in lifestyle factors such as an increase in overtime work, change to non-sedentary work and increased frequency of eating between meals (P < 0.01, P < 0.01 and P = 0.02, respectively). Conclusion Fatigue in salaried workers as measured by the vitality domain of the SF-36 is predicted by an increase in overtime work, change to non-sedentary work and an increase in the frequency of eating between meals. [ABSTRACT FROM AUTHOR]