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In Japan, Karoshi, which means "death from overwork", has become a focus of social concern. However, no previous study has examined long working hours and job strain simultaneously in relation to incidence of cardiovascular events (CVE) in Japanese workers. We prospectively evaluated the relation between job strain or long working hours and risk of CVE in treated hypertensives during the years 1994-2000. In this study, we followed a sample of 1,615 participants (908 men and 707 women) aged 40-65 yr who were working more than 5 working hours per day. Participants completed questions about work-related conditions and lifestyle variables at baseline, and were free of diagnosed cardiovascular disease, stroke or cancer. Job strain (the combination of job demands and job control) was assessed using a simple questionnaire developed with reference to Karasek's model. The main outcome measure was incidence of CVE. During the mean follow-up period of 5.6 yr, we documented 38 cases of initial CVE. Analyses were conducted using the Cox proportional hazard model. We found a significant association between incidence of CVE and job strain categories, but not long working hours. Multivariate relative risks for CVE in active jobs and high strain jobs overall were 2.89 (95% CI: 1.33-6.28) and 2.45 (95% CI: 0.87-6.93); for men 2.94 (95% CI: 1.29-6.73) and 1.86 (95% CI: 0.51-6.75), and for women 3.97 (95% CI: 0.34-46.88) and 9.05 (95% CI: 1.17-69.86), respectively. In conclusion, active jobs and high strain jobs were associated with increased risk of CVE for treated hypertensive workers.

We conducted a nested case-control study to evaluate the relationship between antihypertensive agent class and the incidence of initial cardiovascular events. A total of 7.443 patients being treated with an antihypertensive agent in 1985-1986 were enrolled for follow-up of up to 5 years. A total of 362 patients (186 males and 176 females) developed cardiovascular events. Age (5-year interval) and sex-matched controls were then randomly selected. A Multiple logistic regression analysis was done to control for the effects of confounding factors. The results showed that the use of diuretics and beta-blockers was associated with a reduced risk of cardiovascular events (odds ratio [OR] =0.65, 95% confidence interval [CI]: 0.49-0.86, and OR=0.75, 95% CI: 0.56-1.02, respectively), against a significantly raised risk associated with the use of calcium antagonists (OR=1.34, 95% CI: 1.03-1.80). However, as far as stroke was concerned, there was no significant association of risk with the use of any agent. The control group was found to be similar to the case group with respect to the changes in the treatment program during the follow-up period. The results suggest that the calcium antagonists used in Japan during the period of 1985-1990 constituted a potential risk for the occurrence of cardiovascular events.

The relationship between cerebro-cardiovascular events (CCE) and work-related factors was examined in a cohort of 899 treated hypertensive men who were aged 50-59 yr and working more than 7 portal to portal hours (PPH). During the follow-up of 2.8 yr (2, 513 person-years), 27 cases of CCEs occurred, which were classified into 18 cases of stroke, 7 cases of acute myocardial infarction, and 2 cases of others. Using univariate analysis, it was found that managerial position and long PPH (more than 11 h) were significantly related to CCE (relative risk of 3.0 and 2.2, respectively) as well as risk factors such as emaciation, left ventricular hypertrophy, excessive sleeping hours, obesity, cigarette smoking, and inadequate control of systolic blood pressure. Using Cox proportional hazards general model, both managerial position and long PPH remained independently related to the risk of CCE (hazards ratio and 95% confidence interval, 4.1; 1.7-10.0 and 2.7; 1.1-6.2, respectively), after adjustment for other risk factors. These findings suggested that work-related factors, such as managerial position and long PPH, are independent risk factors of CCE among treated hypertensive male workers in the fifth decade.

僧帽弁輪石灰化 (MRC) の大きさと弁膜症発生要因を検討した. 対象は昭和47年2月より昭和50年2月までに行った60歳以上の老年者600例の連続剖検で, MRC例の臨床所見および病理所見を調査した.(1) 頻度. MRCは計600例中60例 (10%) で, 男6.7%, 女13.3%と性差は有意である (p

The incidence, the size of mitral ring calcification (MRC) and its relation to the mitral valve disease were examined in a total of 600 consecutive autopsy cases of over 60 years of age. (1) The incidence of MRC was 10% (60 cases among 600), and the sex difference was statistically significant with 6.7% in male and 13.3% in female (p less than 0.01). The age was 82 years in average, and an increase of its incidence with aging was significant only in female (p less than 0.005). (2) MRC was found in the annulus of the posterior mitral leaflet. The length of MRC was 12.5 +/- 10.3 mm in male, and 31.8 +/- 23.5 mm in female (p less than 0.01). Large MRC more than 30 mm were found in 1 man and 19 women. (3) The relationship between the length and cross sectional diameter of the MRC showed a positive correlation (r=0.75). Three cases of mitral stenosis or combined stenosis and regurgitation belonged to the extremely large MRC group. (4) There were 27 cases with systolic murmur; 3 holosystolic and 24 ejection type. In large and small MRC groups, systolic murmurs were found in 70% and 33% (p less than 0.05), MRC extending to the anterior leaflet in 65% and 2.5% (p less than 0.005), moderate to severe calcification of the aortic valve in 40% and 20% (n.s.), respectively. (5) X-ray films were examined retrospectively, and large MRC was diagnosed in 85%, and incidence of calcification in the other soft tissues (trachea, bronchi, costal cartilage, aortic arch, thoracic and abdominal aorta) was higher in large MRC group than in the control group (87 cases) without MRC (p less than 0.005).