To observe the association between adverse psychosocial job characteristics, measured by the Karasek job demand-control questionnaire, and a lipid profile, cross-sectional analyses were performed for a Japanese rural working population. The study population comprised 3, 333 male and 3, 596 female actively employed workers, aged 65 years and under. Among men, higher psychological demands were associated with high total cholesterol levels, with an adjusted difference from the top to bottom tertiles of 3.3 mg/dl (F = 3.03; P = 0.048). High demands were also positively associated with the total/HDL cholesterol ratio (F = 3.94; P = 0.020). Neither job control nor job strain (the ratio of demands to control) was associated with any of the lipid levels in either gender. A psychologically demanding job may be associated with an unfavorable lipid profile, but the impact of job strain on atherogenic lipids is negligible. J Epidemiol 2003;13:63-71.
We evaluated the association between changes in psychosocial conditions (assessed in 1992 and 1998) and subsequent mortality through 2001 among 741 Japanese elderly people living in a city located on Osaka in 1992. After adjustment for potential predictors of mortality, the relative risk of mortality, compared with subjects who continued to participate in social activities, was 1.44 (95% confidence interval [CI]: 0.47-4.40), 4.03 (95% CI: 2.11-7.67), and 2.31 (95% CI: 1.28-4.17) for those who started, discontinued, and did not participate at any time, respectively. The multivariate-adjusted relative risk of mortality, compared with those who did not find human relationships difficult in either survey, was 0.88 (95% CI: 0.26-3.05) for those who did not find such relationships difficult in the second survey, 1.73 (95% CI: 1.03-2.88) for those who occasionally found them difficult, and 6.62 (95% CI: 2.43-18.03) for those who continuously did so. The multivariate-adjusted relative risk of mortality, relative to those who consistently considered life worth living (Ikigai), was 0.72 (95% CI: 0.28-1.87), 2.22 (95% CI: 1.44- 3.42), and 1.46 (95% Cl: 0.65-3.31) for those who found, lost, and did not find life worth living in either survey, respectively. Deterioration in psychosocial conditions as well as continuously poor psychosocial conditions may be an important determinant of mortality risk for elderly people. J Epidemiol 2003;13:72 -79.
The intake of food and nutrients differs between urban and rural areas in China. To develop a practical semi-quantitative food frequency questionnaire to cover both the urban and rural areas, we conducted diet surveys and compared food and nutrient intake between the two areas. We recruited 198 urban and 214 rural healthy inhabitants aged 35-55 years, and performed diet surveys, using a 3-day weighed dietary record approach. The intake of 29 nutrients was calculated according to actual consumption of foods, with Standard Food Composition Tables for China and Japan. Then, contribution analysis and multiple regression analysis were employed to select food items covering up to a 90% contribution and a 0.90 R2 of coefficient of determination, respectively. Consumption of energy and carbohydrates was greater in the rural area, but mean protein intake was higher in the urban case. Values for total fat were greater for rural than for urban males, with animal fat as the major contributor. We finally selected 117 and 76 food items for the urban and rural semi-quantitative food frequency questionnaires, respectively, covering 18 and 27 nutrients constituting up to 90% of the nutrient intake. Further validity and reproducibility tests are now needed to assess their appropriateness for usage. J Epidemiol 2003;13:80-89.
Cigarette smoking has been reported to protect women against pre-eclampsia. We conducted a cohort study of 493 women whose first antenatal visits were between September 1997 and April 1998 at Osaka Prefectural General Hospital, Japan. A self-administered questionnaire survey for lifestyles was carried out during pregnancy, and pregnancy outcome information was taken from medical record data. Of 493 subjects, 82 cases (16.6%) developed mild pre-eclampsia and 3 cases (0.6%) developed severe one. The prevalence of cigarette smokers decreased from 21.3% to 8.6% during early pregnancy. The incidence rate of pre-eclampsia among smokers was slightly greater than that among nonsmokers (19.4% vs 17.1%), the incidence rate among cases exposed from household smoking was greater than that among no exposed cases (19.6% vs 14.3%), and the incidence rate among alcoholdrinkers was greater than that among non-drinkers (21.1 % vs 15.1 %). However, there were no statistically significant differences. Larger body mass index before pregnancy tended to be associated with the increased incidence rate of pre-eclampsia (p=0.160). Pregnant women with smoking had a statistically higher frequency of household smoking exposure and having drinking alcohol. Household smoking exposure and drinking alcohol status adjusted hazard rate ratio was 1.1 for smokers (95% confidence interval 0.6-1.7) as compared with that for non-smokers. Our results did not support the proposition that cigarette smoking protected women against pre-eclampsia. J Epidemiol2003;13:90-95.
This paper presents information on Japan's contribution to reputable epidemiologic journals as compared to other leading countries. Ten journals in the field of epidemiology with high impact factors were selected. Articles published in these journals during the period between 1991 and 2000 were searched for the authors' affiliation using Medline database. We found that Japan contributed only 1.1% of the total number of articles published and ranked 14th among all the countries. The United States of America contributed 56.3% of the total and ranked top followed by the United Kingdom (7.6%), Canada (4.1%), and the Netherlands (3.5%). In a time trend analysis, Japan's share of articles did not increase significantly in the last decade (p=0.41). Barriers in conducting epidemiologic research in Japan should be identified and appropriate measures should be taken accordingly. J Epidemiol 2003; 13:96-98.
The US nuclear weapons testing program in the Pacific conducted between 1946 and 1958 resulted in radiation exposure in the Marshall Islands. The potentially widespread radiation exposure from radioiodines of fallout has raised concerns about the risk of thyroid cancer in the Marshallese population. The most serious exposures and its health hazards resulted from the hydrogen-thermonuclear bomb test, the Castle BRAVO, on March 1, 1954. Between 1993 and 1997, we screened 3, 709 Marshallese for thyroid disease who were born before the BRAVO test. It was 60% of the entire population at risk and who were still alive at the time of our examinations. We diagnosed 30 thyroid cancers and found 27 other study participants who had been operated for thyroid cancer before our screening in this group. Fifty-seven Marshallese born before 1954 (1.5%) had thyroid cancer or had been operated for thyroid cancer. Nearly all (92%) of these cancers were papillary carcinoma. We derived estimates of individual thyroid dose proxy from the BRAVO test in 1954 on the basis of published age-specific doses estimated on Utirik atoll and 137Cs deposition levels on the atolls where the participants came from. There was suggestive evidence that the prevalence of thyroid cancer increased with category of estimated dose to the thyroid. J Epidemiol2003;13:99-107.
Automobile exhaust is considered to be a potential risk factor for respiratory diseases. To investigate the effects of traffic-related air pollution on respiratory symptoms among children who lived near trunk roads, we conducted a cohort study on 2, 506 schoolchildren in eight different communities in Japan. Over that four-year period, the prevalence of asthma was higher among girls who lived less than 50 m from trunk roads (roadside areas) than among girls in the other areas studied. Testing for trends showed that the prevalence of asthma among girls increased significantly with increases in the concentration of air pollution in each area. Among boys, the prevalence of asthma did not differ in relation to the distance from roads, although the rate was higher in urban areas than in rural areas. The incidence of asthma during the follow-up period significantly increased among boys living in roadside areas relative to rural areas (odds ratio = 3.75; 95% confidence interval: 1.00-14.06). Among girls, the incidence of asthma also increased (odds ratio = 4.06; 95% confidence interval:0.91-18.10), although the risk was not significant. These findings suggest that traffic-related air pollution may be of particular importance in the development of asthma among children living near major trunk roads with heavy traffic. J Epidemiol 2003;13:108-119.
Background: Recent randomized controlled trials indicated that exercise training for elderly significantly increased their physical fitness. However, very few studies have examined changes in physical activity after exercise training. The purpose of this study was to investigate whether six-month exercise training for older adults can increase and maintain their physical activity in daily life. Methods: Sixty-two men and women aged 60 to 81 years (mean age 67.1 years), living in communities, were randomly allocated into an exercise group (n=32) or a control group (n=33). The intervention started in April 1998 and lasted for 25 weeks. The exercise regimen consisted of endurance training and resistance exercises in a two-hour class conducted at least twice a week. The subjects completed a physical activity diary at each pre-intervention (March 1998), post-intervention (September 1998) and follow-up (April 1999) measurement of physical activity. Physical activity, expressed as total daily energy expenditure, was calculated by multiplying the amount of time spent in each activity and the corresponding METs. Results: Total daily energy expenditure significantly increased from 40.8 kcal/kg/day to 43.5 kcal/kg/day in the exercise group (p=0.03), but did not change in the control group. At the follow-up measurement, the mean total daily energy expenditure in the exercise group remained significantly higher, by 1.7 kcal/kg/day, than that at the pre-intervention (p=0.05). Conclusions: This randomized controlled trial indicated that exercise training for elderly was effective in increasing physical activity in daily life. J Epidemiol2003;13:120-126.