Kazunori Kayaba

Correlation between lipoprotein(a) and aortic valve sclerosis assessed by echocardiography (the JMS Cardiac Echo and Cohort Study)

An elevated serum level of lipoprotein(a) (Lp[a]) may be an independent risk factor for atherosclerotic disease, but the relation of Lp(a) to aortic valve (AV) sclerosis has not been determined. We measured serum concentrations of Lp(a) and investigated their relation to the presence of echocardiographic AV sclerosis in residents of a rural village in Japan. We measured serum Lp(a) levels in 347 men and 437 women aged 35 to 90 years (mean +/- SD: 62 +/- 11 years) who participated in mass screening examinations in Wara village, Gifu, Japan. AV sclerosis was assessed by long- and short-axis 2-dimensional echocardiographic views and continuous-wave Doppler echocardiography. AV sclerosis was graded as follows: 0 = normal AV; 1 = increased echo density; 2 = thickening or calcific deposits > or = 3 mm; and 3 = same as 2 with mildly restricted motion (pressure gradient < 16 mm Hg). Lp(a) levels ranged from < 1 mg/dl to 153 mg/dl. The 25th, 50th, and 75th percentile values were 7, 16, and 28 mg/dl, respectively. Lp(a) levels were significantly higher in women than in men (p < 0.01), and did not increase significantly with age. The prevalence of AV sclerosis (grades 2 and 3) increased significantly with age (p < 0.001). AV sclerosis was present in 65 (36.1%) of 180 subjects with Lp(a) levels > or = 30 mg/dl and in 77 (12.7%) of 604 subjects with Lp(a) levels < 30 mg/dl (p < 0.001). There were no significant differences in the prevalence of AV sclerosis in terms of sex, blood pressure, or levels of total cholesterol, high-density lipoprotein cholesterol, triglycerides, or blood sugar. We conclude that increased serum levels of Lp(a), as well as aging, are closely related to AV sclerosis.

Dietary patterns and levels of blood pressure and serum lipids in a Japanese population.

Background Associations between dietary patterns and cardiovascular disease risk factors remain unclear. The objective of this study was to evaluate the association between dietary patterns derived from factor analysis and the levels of blood pressure and serum lipids in a Japanese population. Methods We conducted a cross-sectional analysis among 6886 (in the analysis on blood pressure) and 7641 (in the analysis on serum lipids) Japanese subjects aged 40-69 years. Dietary patterns were identified from a food frequency questionnaire by factor analysis. Associations between dietary patterns and blood pressure and serum lipids were examined after taking potential confounders into account. Results Three dietary patterns were identified: vegetable, meat, and Western. In men, the meat pattern was associated with higher total, high-density lipoprotein (HDL), and low-density lipoprotein (LDL) cholesterol. The Western pattern was associated with higher total and LDL cholesterol. In women, the vegetable pattern was associated with lower systolic and diastolic blood pressure and pulse pressure, and higher HDL cholesterol. The meat pattern was associated with higher total and HDL cholesterol. The Western pattern was associated with higher total, HDL, and LDL cholesterol, and the least intake pattern of Western diet was associated with higher systolic and diastolic blood pressures. Conclusions Dietary patterns of a Japanese population were related to cardiovascular disease risk factors, especially in women.

Prospective Study on Occupational Stress and Risk of Stroke

BACKGROUND No prospective studies have examined the association between occupational stress according to the job demand-control model and the risk of stroke in Asian populations. METHODS We conducted a multicenter community-based prospective study of 6553 Japanese male and female workers. Occupational stress was evaluated using a Japanese version of the job demand-control model questionnaire. We used the Cox proportional hazards model to evaluate the association between occupational stress and stroke. RESULTS During a mean follow-up of 11 years, we identified 147 incident strokes. Multivariable analysis revealed a more than 2-fold increase in the risk of total stroke among men with job strain (combination of high job demand and low job control) (hazard ratio, 2.73; 95% confidence interval, 1.17-6.38) compared with counterpart men with low strain (combination of low job demand and high job control) after adjustment for age, educational attainment, occupation, smoking status, alcohol consumption, physical activity, and study area. Additional adjustments for biologic risk factors attenuated the hazard ratio, but there continued to be statistical significance (hazard ratio, 2.53; 95% confidence interval, 1.08-5.94). In women, no statistically significant differences were found for any stroke incidence among the job characteristic categories. CONCLUSION Occupational stress related to job strain was associated with incident strokes among Japanese men.

Increasing incidence of Kawasaki disease in Japan: Nationwide survey

Background: The last nationwide survey of Kawasaki disease in Japan was conducted in 2003; the epidemiologic features of the disease in Japan since then are unknown.

Sleep Duration and Incidence of Cardiovascular Events in a Japanese Population: The Jichi Medical School Cohort Study

Background Although sleep is one of the most important health-related factors, the relationship between sleep duration and the incidence of cardiovascular events has not been fully described. Methods The present study comprised the 11 367 study subjects (4413 men and 6954 women) of the Jichi Medical School Cohort Study, a population-based prospective study. Baseline data were obtained by questionnaire and health examinations between April 1992 and July 1995 in 12 rural areas in Japan, and the main outcome measures were the incidence of cardiovascular diseases (stroke and myocardial infarction [MI]). Cox proportional hazards models were used to analyze the association between sleep duration and the incidence of cardiovascular events. Results A total of 481carciovascular events (255 men and 226 women) were observed during an average follow-up period of 10.7 years. After adjusting for age, systolic blood pressure, serum total cholesterol, body mass index, smoking habits, and alcohol drinking habits, the hazard ratios (95% confidence intervals) for the incidence of cardiovascular diseases for individuals sleeping less than 6 hours and 9 hours or longer were 2.14 (1.11–4.13) and 1.33 (0.93–1.92) in men, and 1.46 (0.70–3.04) and 1.28 (0.88–1.87) in women, respectively, relative to those who reported sleeping 7 to 7.9 hours per day. Conclusions Our data indicate that men who sleep less than 6 hours a day have a higher risk of cardiovascular events than those sleeping 7 to 7.9 hours.

Association between job characteristics and health behaviors in Japanese rural workers

Associations between job characteristics defined by the Karasek’s job demand-control model and health behaviors were investigated in a cross-sectional analysis of 6,759 Japanese rural workers. High psychological demands were associated with heavy smoking, exaggerated prevalence of alcohol drinking, and high work-related physical activity. Low job control was associated with lower consumption of vegetables, a smaller quantity number of cigarettes smoked, and a low level of work-related physical activity. Job strain, a combined measure obtained from the ratio of demands to control, was associated with lower vegetable consumption, low prevalence of smoking, and high prevalence of current alcohol drinking. Stratified analyses by occupations and gender provided some but not allof the explanations for the unexpected findings. The results indicate a possible association between psychosocial job characteristics and health behaviors. A few unexpected findings prevent complete support to one of the hypothetical pathways that the job characteristics lead to cardiovascular disease through behaviors.

Effect of the angiotensinogen gene Met235→Thr variant on blood pressure and other cardiovascular risk factors in two Japanese populations

Objective: To investigate the gene frequency of the T235 allele and its relationship with hypertension in two Japanese populations. Methods: T235 was investigated by restriction fragment length polymorphism using the polymerase chain reaction technique in 213 Japanese males aged 40–59 years, who were randomly selected from participants in the Jichi Medical School Cohort Study (Awaji-Hokudan population, n = 157; Niigata-Yamato population, n = 56). Results: The gene frequency of the T235 allele in the two populations was very similar (Awaji-Hokudan 0.65, Niigata-Yamato 0.62; mean 0.64). The T235 frequency was 0.60 in normotensive males, approximately 1.2− to 1.7-fold that in Caucasians. Hypertension, in particular that associated with a positive family history of hypertension, was more common in individuals homozygous for the T235 allele. The levels of total cholesterol, blood glucose and fibrinogen showed a weak and non-significant relationship with the angiotensinogen genotype. Conclusion: The T235 angiotensinogen allele was more common in Japanese than in Caucasians, and was a predisposing factor for hypertension.

Frequency of Citrus Fruit Intake Is Associated With the Incidence of Cardiovascular Disease: The Jichi Medical School Cohort Study

Background It has been reported that fruit intake protects against cardiovascular disease (CVD). However, most of the relevant studies were conducted in Western countries, and only a few investigated Japanese populations. The present cohort study assessed the effect of citrus fruit intake on the incidence of CVD and its subtypes in a Japanese population. Methods A baseline examination consisting of physical and blood examinations and a self-administered questionnaire was conducted during the period from April 1992 through July 1995. Dietary habits were assessed using a food frequency questionnaire that was divided into 5 categories. Citrus fruit was examined separately due to its frequent consumption by the general Japanese population. Using the Cox proportional hazards model, data from 10 623 participants (4147 men, 6476 women) who had no history of CVD or carcinoma were analyzed to assess the association between frequency of citrus fruit intake and CVD incidence. Results Frequent intake of citrus fruit was associated with a lower incidence of CVD: the hazard ratio for almost daily intake versus infrequent intake of citrus fruit was 0.57 (95% confidence interval: 0.33–1.01, P for trend = 0.04) in men and 0.51 (0.29–0.88, P for trend = 0.02) in women. Frequent intake of citrus fruit was also associated with lower incidences of both all stroke and cerebral infarction, but not hemorrhagic stroke or myocardial infarction. Conclusions Frequent intake of citrus fruit may reduce the incidence of CVD, especially cerebral infarction, in men and women.

Low Control at Work and the Risk of Suicide in Japanese Men: A Prospective Cohort Study

Background: Although adverse psychosocial job characteristics are suspected predictors of suicide death, prospective studies based on established stress instruments are limited. Methods: In a multicenter community-based Japanese cohort study, we prospectively investigated the association between psychosocial job characteristics and the risk of death from suicide among male workers. Baseline examination was conducted from 1992 to 1995 to determine the socioeconomic, behavioural and biological variables in addition to the psychosocial job characteristics of 3,125 male workers aged 65 and under and free from major illness. Low job control and high job demands were measured as adverse psychosocial job characteristics according to a job demand-control model questionnaire. Suicide deaths were identified using the Cause-of-Death Register. Results: During the 9-year follow-up, 14 suicides were identified. The suicide death rate was 48.1 per 100,000 person years. Multivariate analysis revealed a more than fourfold increase in the risk of suicide among men with low control at work (relative risk: 4.10; 95% confidence interval: 1.31–12.83) compared with counterpart men after adjustment for age, marital status, educational attainment, occupation, smoking status, alcohol consumption, total cholesterol level, and study area. Job demands were not associated with risk of death from suicide. Conclusions: By using a job demand-control model questionnaire, low control at work was revealed as a predictor of suicide death among Japanese male workers. The finding implies that job redesign aimed at increased worker control could be a worthwhile strategy in preventing, or at least reducing, the risk of suicide death.

Incidence of total stroke, stroke subtypes, and myocardial infarction in the Japanese population: the JMS Cohort Study.

Background Previous reports indicated that the incidence rate of stroke was higher in Japan than in Western countries, but the converse was true in the case of myocardial infarction (MI). However, few population-based studies on the incidence rates of stroke and MI have been conducted in Japan. Methods The Jichi Medical School (JMS) Cohort Study is a multicenter population-based cohort study that was conducted in 12 districts in Japan. Baseline data were collected between April 1992 and July 1995. We examined samples from 4,869 men and 7,519 women, whose mean ages were 55.2 and 55.3 years, respectively. The incidence of stroke, stroke subtypes, and MI were monitored. Results The mean follow-up duration was 10.7 years. A total of 229 strokes and 64 MIs occurred in men, and 221 strokes and 28 MIs occurred in women. The age-adjusted incidence rates (per 100,000 person-years) of stroke were 332 and 221 and those of MI were 84 and 31 in men and women, respectively. In the case of both sexes, the incidence rates of stroke and MI were the highest in the group of subjects aged > 70 years. Conclusion We reported current data on the incidence rates of stroke and MI in Japan. The incidence rate of stroke remains high, considerably higher than that of MI, in both men and women. The incidence rates of both stroke and MI were higher in men than in women.