What unfavorable factors are associated with low serum total cholesterol in a Japanese population?

Dyslipidemia and cardiovascular disease: a series of epidemiologic studies in Japanese populations

Although the causal relationships of high serum levels of total cholesterol (TC) and low-density lipoprotein cholesterol (LDL-C) with coronary artery disease (CAD) are well established, there have been few community-based epidemiologic studies of these relations in Japan. Furthermore, even when analysis is restricted to ischemic stroke, the relationship between dyslipidemia and stroke is very weak. Accordingly, it is difficult to perform cohort studies of dyslipidemia and cardiovascular disease. A series of studies, such as the NIPPON DATA (National Integrated Project for Prospective Observation of Non-communicable Disease and Its Trends in the Aged) cohort study of a representative sample of Japanese, have greatly increased existing evidence. NIPPON DATA80 revealed a clear positive relationship between TC and CAD, and indicated that reverse causality between hypocholesterolemia and liver disease may increase all-cause mortality in hypocholesterolemic Japanese. NIPPON DATA90 showed that serum high-density lipoprotein cholesterol (HDL-C) was inversely associated with all-cause mortality, even when HDL-C was very high. NIPPON DATA80 revealed that low-normal levels of serum albumin and TC are associated with a decline in activity during old age, especially in women. The Suita study-a unique cohort study of urban residents-showed that LDL-C and non-HDL-C were equally accurate in predicting the incidence of myocardial infarction. Further research of this quality is needed to ascertain the public health burden of dyslipidemia in Japan.

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

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 (<4.14mmol/L, 160mg/dl) and highest (>or=6.71mmol/L, 260mg/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.

Relationship between turnover and periodic health check-up data among Japanese hospital nurses: a three-year follow-up study

The present study explored the relationship between turnover and periodic health check-up data among Japanese hospital nurses. The subjects were 379 registered nurses in a Japanese hospital and the duration of our study period was three years. By the proportional hazard model, we investigated the relative risks (RRs) of the turnover rate associated with the following: lifestyles (irregularity of meals, taking breakfast), work environment (working hours, work schedule), and health status (body mass index [BMI], serum total cholesterol [T-cho], taking medication, sleep disturbance). We obtained the data on turnover from October, 1997 to September, 2000. During the observed period we were able to follow up on 363 female nurses (96%) and the turnover total amongst them was 100. We divided the subjects into a younger (21-25-yr-old) and an older (>25-yr-old) group because of the interaction between age and turnover. In the younger group, we found that sleep disturbance influenced turnover significantly. On the other hand, in the older nurses, BMI and T-cho contributed to turnover significantly. Our results imply the possibility of a partial association between turnover and periodic health check-up data among the nurses.

What cause of mortality can we predict by cholesterol screening in the Japanese general population?

OBJECTIVE

In a population with a markedly lower coronary mortality such as in Japan, the benefit of cholesterol screening may be different from Western populations. We attempted to assess the importance of cholesterol screening in Japan.

DESIGN

A 13.2-year cohort study for cause-specific mortality.

SETTING

Three hundred randomly selected districts throughout Japan in which the National Survey on Circulatory Disorders 1980 was performed.

SUBJECTS

A total of 9216 community dwelling persons aged 30 years and over, with standardized serum cholesterol measurement and without a past history of cardiovascular disease.

RESULTS

There were 1206 deaths, which included 462 deaths due to cardiovascular disease with 79 coronary heart diseases. Hypercholesterolemia (>6.21 mmol L-1) showed a significant positive relation to coronary mortality (relative risk; 2.93, 95% confidence interval; 1.52-5.63) but not to stroke. Although hypocholesterolemia (<4.14 mmol L-1) was significantly associated with an increased risk of liver cancer, noncardiovascular, noncancer disease and all-cause mortality, these associations, except for liver cancer, disappeared after excluding deaths in the first 5 years of the follow-up. The multivariate adjusted attributable risk of hypercholesterolaemia for coronary disease was 0.98 per 1000 person-years, which was threefold higher than that of hypocholesterolemia for liver cancer: 0.32 per 1000 person-years. The attributable risk percentage of hypercholesterolaemia was 66% for coronary heart disease.

CONCLUSION

Similar to Western populations, it is recommended to provide screening for hypercholesterolaemia in Japan, especially for males, although its attributable risk for coronary disease might be small.