土居 弘幸

Obesity in children is a serious public health problem, and TV viewing is considered a potential risk factor. Since, however, no relevant association studies have been conducted in Japan, we evaluated the association between TV viewing and obesity using a population-based study conducted in a Japanese town. All 616 preschool children in the town were enrolled in February 2008, and a self-administered questionnaire to collect children's and parents' characteristics was sent to the parents. We dichotomized the time spent TV viewing and evaluated associations by logistic regression using a "less than 2h" category as a reference. The questionnaire was collected from 476 participants (77.3%), of whom 449 were available for the final analyses. Among them, 26.9% of preschool children reported 2 or more hours of TV viewing per day and 8.2% were defined as obese. In logistic regression analyses, there was no positive association in unadjusted (odds ratio [OR]1.11, 95% confidence interval [95% CI]:0.50-2.49) or adjusted models for exclusively breastfed status, sleep duration, or maternal factors (OR1.11, 95% CI:0.50-2.51). We also found no positive association between TV viewing and overweight status, possibly owing to the influence of social environment, low statistical power, or misclassification.

A cross-sectional study was conducted to evaluate the association between dietary intake and depressivesymptoms in community-dwelling elderly persons. Five-hundred elderly persons aged 65 to 75 years were randomly selected from the population of O city in Okayama Prefecture, Japan. Among 401 respondents (response rate, 80.0%), data from 279 (133 males, 146 females) who completed the questionnaire concerning dietary intake and depressive state were analyzed using logistic regression. Each of 17 dietary intakes was classified into tertiles:high intake, moderate intake, and low intake. The Center for Epidemiology Studies Depression scale (CES-D) was used. Among males, the observed odds ratios (the 95% confidence intervals) for the depressive state were 0.36 (95% CI:0.13-0.98) in the highest tertile of carotene intake, 0.33 (95% CI:0.12-0.93) in the highest tertile of vitamin C intake, 0.29 (95% CI:0.10-0.85) in the highest tertile of carbohydrate intake, and 0.33 (95% CI:0.12-0.92) in the medium tertile of vitamin E intake. Among females, similar results were observed, but these results were not statistically significant. The results suggested that carbohydrate, carotene, and vitaminC intakes are associated with lowering depressive symptoms among elderly persons dwelling in communities in Japan.

To investigate the effect of exclusive breastfeeding on the likelihood of Japanese preschool children being overweight, population-based cross-sectional survey data from M town in Japan were used. Using the population registry of this town, all 616 preschool children were identified, and a self-administered questionnaire was sent to their parents. The exposure variable of interest was exclusive breastfeeding from birth to 6 months, and the outcome variable of interest was the children being overweight at preschool age. Statistical analyses used included logistic regression and sensitivity analyses. In the final analyses, we included 448 preschool children. Although all point estimates indicated a protective effect, logistic regression analyses showed no significant reduction in being overweight due to exclusive breastfeeding in the unadjusted model (odds ratio (OR)0.70, 95% confidence intervals:0.30-1.64), the model adjusted for birth weight (OR0.70, 95% CI:0.30-1.63), the model adjusted for child lifestyle (OR0.71, 95% CI:0.30-1.67), or the model adjusted for parental factors (OR0.46, 95% CI:0.15-1.37). In sensitivity analyses, point estimates were not significant, but a protective effect was observed. In conclusion, our results suggest that breastfeeding might have a protective effect on Japanese preschool children against being overweight, although statistical significance was not observed due to the limitation of the statistical power of the findings.

The annual number of suicides in Japan increased sharply in 1998, and since that time it has consistently exceeded 30,000 per year. In this study, we analyze a database of personal and background characteristics of 824 cases (605 men, 219 women) who completed suicide in Okayama Prefecture in 2002 and 2003. The data were obtained with cooperation from the police. Using the methodologies in a previous European study as a model, we classified the suicide methods into 8 categories. To examine the generational and regional differences in the choice of methods, we stratified the sample into 4 age groups (<-24, 2544, 4564, and >-65) and 2 regional groups (Okayama/Kurashiki vs. other areas). Our results on gender differences in 7 of the suicide methods were mostly similar to the European data. However, our data showed a remarkably higher proportionate male-to-female mortality ratio for poisoning by other substances (ICD-10, X65-X69 codes) (1.83, 1.15-2.92). In terms of generational differences in the choice of suicide methods, the Mantel-Haenszel test of homogeneity was significant for most of the categories in our study, suggesting an impact of age on how people commit suicide. There were no remarkable regional differences in our sample. An epidemic curve for suicides via carbon monoxide poisoning using charcoal briquets revealed a trend of time clustering not observed in the other 6 means. The database constructed and used in this study contains richer information than conventional death statistics and is expected to provide helpful knowledge and insights for future epidemiological studies.

Leptin is a hormone which is predominantly secreted by adipose tissue. Recent studies have shown that leptin increases arterial blood pressure. Although data from available animal studies clearly indicate an association between leptin and hypertension, results of human studies have been less definitive. We conducted a case-control study to examine the association between serum leptin levels and hypertension in 111 hypertensive subjects and 222 male controls, using conditional logistic regression analyses. Mean serum leptin levels were found to be marginally higher in the case subjects than in the control subjects (3.3 ng/ml versus 3.0 ng/ml), however, conditional logistic regression analysis revealed that subjects in the highest quartile had a significantly increased risk of hypertension compared with those in the lowest quartile, even after adjusting for drinking status and diabetes mellitus (adjusted OR, 2.11;95% CI, 1.01-4.39). Our findings suggest that leptin plays an important role in the development of hypertension.

The purpose of the present study was to assess the association between job strain and smoking cessation among Japanese male employees. In 1997, a baseline questionnaire was given to 2,625 (2,113 males and 512 females) employees of an electronics firm in Gifu Prefecture, Japan. The self-administered questionnaire was a set of questions on smoking habits and consisted of items on socio-demographic variables and smoking habits, including the Japanese version of the Job Content Questionnaire (JCQ). The JCQ consists of scales of job control, job demand, supervisory support, coworker support, job insecurity, physical demands, and isometric load. A total of 733 male smokers were then followed for 2 years, with 446 completing a follow-up questionnaire in 1999 (follow-up rate, 61%). Logistic regression analyses were performed to examine associations between job strain and smoking cessation. Among the 446 participants, 38 had quit smoking. After adjusting for age ((odds ratio: OR) = 0.38, 95% (contidence interval: CI) = 0.15-0.94), men with a high level of physical demands at baseline showed a lower smoking cessation rate at follow-up than did those with a low level. However, when adjustments were made for age and other socio-demographic variables, the odds ratio of smoking cessation showed marginal significance (OR = 0.45, 95% CI = 0.16-1.29). There was no significant association between other job strain variables and smoking cessation at the 2-year follow-up. No significant association was found between job strain and change in the number of smoked cigarettes per day. The present study did not support the hypothesis that higher levels of job stressors are associated with a lower rate of smoking cessation among men.

We evaluated the infection risks in the neonatal intensive care unit (NICU) using data of NICU infection surveillance data. The subjects were 871 NICU babies, consisting of 465 boys and 406 girls, who were cared for between June 2002 and January 2003 in 7 medical institutions that employed NICU infection surveillance. Infections were defined according to the National Nosocomial Infection Surveillance (NNIS) System. Of the 58 babies with nosocomial infections, 15 had methicillin-resistant Staphylococcus aureus (MRSA) infection. Multiple logistic regression analysis demonstrated that the odds ratio for nosocomial infections was significantly related to gender, birth weight and the insertion of a central venous catheter (CVC). When the birth weight group of more than 1, 500g was regarded as the reference, the odds ratio was 2.35 in the birth weight group of 1,000-1,499g and 8.82 in the birth weight group of less than 1,000g. The odds ratio of the CVC () for nosocomial infection was 2.27. However, other devices including artificial ventilation, umbilical artery catheter, umbilical venous catheter, and urinary catheter were not significant risk factors. The incidence of MRSA infection rapidly increased from 0.3% in the birth weight group of more than 1,500g to 2.1% in the birth weight group of 1,000-1,499g, and to 11.1% in the birth weight group of less than 1,000g. When the birth weight group of more than 1,500g was regarded as the reference, multiple logistic regression analysis demonstrated that the odds ratio was 7.25 in the birth weight group of 1,000-1,499g and 42.88 in the birth weight group of less than 1,000g. These odds ratios were significantly higher than that in the reference group. However, the application of devices did not cause any significant differences in the odds ratio for MRSA infection.