The effects of psychosocial factors on health have drawn growing attention. An important prerequisite for epidemiologic studies is that instruments to measure psychosocial factors be reliable and valid based on psychometric properties. The introduction of occupational stress models has made breakthroughs in conceptualizing real-life complex phenomena in the workplace. This article describes some trials that explore the associations between psychosocial factors and health in the community and workplace. Scales for measuring social support and psychosocial job characteristics were developed, and their validation was pursued. Findings suggest that adverse social relationships and job characteristics measured by these instruments are associated with ill health. To strengthen the validities of the measurements and to provide strong causal evidence between psychosocial factors and health, more prospective studies and interventional approaches are needed. J Epidemiol 2005; 15: 65-69.
BACKGROUND: The relative risk of mortality in low and high body mass index (BMI) categories in various ethnic groups remains a controversial subject. METHODS: To examine the relationship between BMI and mortality, a population-based prospective cohort study was conducted in two areas of Gunma Prefecture, Japan, in 1993. A total of 5,554 men and 5,827 women aged 40-69 years completed a self-administered questionnaire and were followed up until the year 2000. The hazard ratios (HRs) were estimated by the Cox proportional hazards model for different BMI classes. RESULTS: During the seven year follow-up period, 329 men and 147 women died. As compared with those in the reference BMI category (22.0-24.9 kg/m2), men and women in the lowest BMI category (<18.5 kg/m2) had a HR (95% confidence interval [CI]) of death from all-causes of 2.66 (1.59-4.46) and 3.14 (1.38-7.13), respectively, and women in the highest BMI category (28.0+ kg/m2) had a HR of death of 3.25 (1.48-7.15), after adjusting for all possible confounding factors including smoking and after excluding deaths occurring during the first three years of follow-up. CONCLUSION: In this prospective study of a Japanese cohort consisting of subjects ranging in age from 40 to 69 years, the curve depicting the relationship between BMI and all-cause mortality was Lshaped in men and U-shaped in women. J Epidemiol 2005; 15: 70-77.
BACKGROUND: The association between social relationships and lower mortality has been well documented in Western countries. This study aims to investigate that association among elderly Japanese in a rural area. METHODS: An analysis was conducted with 1,994 subjects (58.1% women), 78.3% of the total elderly aged 65 and older in a town, who were independent in activities of daily living. A baseline survey was carried out in 1992, and subjects were followed until 1999. Cox proportional hazard models examined the association between social relationships (availability of casual friend/ support provider, group membership, job, living arrangement) and an 88-month mortality. RESULTS: A significant association between social relationships and mortality was observed among the old-old (aged 75 and older). Among men, having a job and group membership were significantly associated with lower mortality with hazard ratios (95% confidence intervals) of 0.62 (0.41-0.94) and 0.60 (0.40-0.90), respectively, after adjustment for age, diagnosed illnesses, self-rated health, other social relationships, annual income, and home ownership. Among women, having a job and living alone were significantly associated with lower mortality with hazard ratios (95% confidence intervals) of 0.67 (0.45-0.99) and 0.35 (0.13-0.97), respectively. CONCLUSIONS: Social relationships such as having a job and group membership were associated with lower mortality among the old-old. In addition, old-old women living alone were better off in terms of mortality after adjustment for possible confounders. This suggests the importance of considering family relationships in terms of quality in areas where multi-generation households prevail. J Epidemiol2005; 15: 78-84.
BACKGROUND: Rapid socioeconomic development in Japan since the beginning of the Seven Countries Study in 1958 has brought remarkable changes in lifestyle and dietary patterns. We investigated the relationship between time trends in nutrient intake and serum cholesterol levels in a Japanese cohort of the Seven Countries Study, in Tanushimaru, a typical farming town on Kyushu Island. METHODS: Subjects totaled 628 in 1958, 539 in 1977, 602 in 1982, 752 in 1989, and 402 in 1999, and all of the subjects were men aged 40-64 years. Eating patterns were evaluated by 24-hour dietary recall from 1958 through 1989, and by a food frequency questionnaire in 1999. We also measured serum cholesterol levels in each health examination. RESULTS: The total daily energy intake decreased from 2837 kcal in 1958 to 2202 kcal in 1999. The carbohydrate intake in percentage of total daily energy intake decreased markedly, from 84% in 1958 to 62% in 1999, in contrast to large increases during this period in protein intake (from 11% to 18%) and fat intake (from 5% to 20%). In proportion to the dramatic change in protein and fat intake, serum cholesterol levels showed large increases (from 152.5mg/dl to 194.2 mg/ dL). CONCLUSIONS: In spite of such big dietary changes toward a westernized diet, the incidence of coronary artery disease in a rural Japanese area remains low. However, careful surveillance is needed in the future because of the remarkably increasing intake of fats, especially saturated fatty acids. J Epidemiol 2005; 15: 85-89.
BACKGROUND: The role of serum manganese superoxide dismutase (MnSOD) in the development of gastric cancer has not been clearly defined. METHODS: We conducted a case-control study to address the potential relationship between serum MnSOD levels and gastric cancer. Cases were 275 gastric cancer patients and controls were 275 sexand age-matched healthy persons. Serum MnSOD levels were determined by a commercially available enzyme-linked immunosorbent assay (ELISA). RESULTS: The mean(±standard deviation) of serum MnSOD levels was 177.4±87.3 ng/mL among cases and 169.4±56.7 ng/mL among controls. Gastric cancer patients had slightly higher serum MnSOD levels than the controls. After adjustment for pack-years of cigarette smoking and Helicobacter pylori infection, the odds ratio was 1.54(95% confidence interval; 0.79-3.01) for subjects in the highest quartile versus the lowest quartile. No significant differences were observed for serum MnSOD levels in gastric cancer patients according to clinicopathological factors such as disease stage, histological type, venous invasion, and lymph node metastasis. CONCLUSION: Our study suggested that serum MnSOD levels are not significantly associated with the increased risk of gastric cancer, although a weak association may exist. J Epidemiol 2005; 15: 90-95.
BACKGROUND: The prevalence of cardiovascular risk factors and the prevalence of comorbidities in adult hemodialysis patients in Japan are not fully understood. METHODS: In "Kaleidoscopic Approaches to Patients with End-stage Renal Disease Study" (The KAREN Study, 2003), trained research stuff examined 1,214 adult hemodialysis patients (mean age, 61.2 years; 779 males and 435 females) of 1,506 patients in northern areas of Iwate Prefecture. Cardiovascular risk factors and the prevalence of comorbidities in hemodialysis patients were compared with those in the general population using direct age-adjustment methodology and standardized morbidity ratios (SMRs). RESULTS: In hemodialysis patients, common causes of end-stage renal disease were chronic glomerulonephritis (29.8%), diabetic nephropathy (24.5%), and other diseases. Prevalence and SMR of myocardial infarction were 5% and 9.6, respectively, and those of stroke were 13% and 5.7. The prevalences of hypertension and diabetes mellitus were 87% and 29%, respectively. Mean systolic blood pressure and mean diastolic blood pressure were 155 mmHg and 85 mmHg, respectively. Mean levels of total serum cholesterol, high-density lipoprotein cholesterol, and albumin in patients with end-stage renal disease were lower than those of the general population (160.6 vs. 203.3 mg/dL, 48.5 vs. 59.7 mg/dL, and 3.7 vs. 4.4 g/dL, respectively). Mean levels of C-reactive protein were higher than those of the general population (3.80 vs. 1.16 mg/L). CONCLUSION: Hemodialysis patients have a high prevalence of cardiovascular risk factors and comorbidities. Levels of nutrition-related markers were lower, and C-reactive protein levels were higher, in hemodialysis patients than in the general population. J Epidemiol 2005 ;15: 96-105.