Publications (41)121.05 Total impact
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Article: Individual-level social capital and self-rated health in Japan: An application of the Resource Generator.
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ABSTRACT: Despite accumulating evidence of associations between social capital and health in public health research, a criticism of the field has been that researchers have exclusively focused on concepts of social cohesion to the exclusion of individual-level approaches. In the present study, we evaluated the association between social capital measured by the Resource Generator (an individual-level assessment of access to social capital) and self-rated health among Japanese population in a cross-sectional study. A postal survey of 4000 randomly selected residents in Okayama City (western Japan) was conducted in February 2009. We divided the overall scores from the Resource Generator Japan scale into quartiles. Odds ratios (ORs) and 95% confidence intervals (CIs) for self-rated health were calculated separately by sex. Individuals with the highest quartile of scores had significantly lower odds of poor health compared to the lowest group after covariate adjustment among both men and women (men; OR: 0.45, 95% CI: 0.24-0.86, women; OR: 0.44, 95% CI: 0.25-0.79, respectively) and there were also significant dose-response relationships. In the sub-domains of Resource Generator Japan scale, a differential pattern was observed by sex. Women showed a clear dose-response relationship with health across all four sub-scales (domestic resources, expert advice, personal skills, and problem solving resources). In contrast, only the domain of expert advice exhibited a strong association with men's health. Among both men and women individual-level social capital measured by the Resource Generator was related to reduced odds of poor health even after taking into account individual confounders. Although we cannot exclude reverse causation due to the cross-sectional design, our study adds to the accumulating evidence of the potential utility of the Resource Generator for evaluating the relationship between individual-level access to social capital and health.Social Science [?] Medicine 05/2013; 85:32-7. · 2.70 Impact Factor -
Article: Shift Work and Diabetes Mellitus among Male Workers in Japan:Does the Intensity of Shift Work Matter?
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ABSTRACT: The purpose of this study was to examine the association between shift work and diabetes mellitus by separating shift workers according to the intensity of their shift work (seasonal shift work and continuous shift work). Between May and October 2009, we collected data from annual health checkups and questionnaires at a manufacturing company in Shizuoka, Japan. Questionnaires were returned by 1,601 workers (response rate:96.2%, men/women＝1,314/287). Diabetes mellitus was defined as hemoglobin A1c>6.5% and fasting blood sugar>126mg/dl. After exclusions, which included all the women and clerical workers because they did not work in shifts, we analyzed 475 skilled male workers. After adjusting for age, smoking status, frequency of alcohol consumption, and cohabitation status, odds ratios for diabetes mellitus were 0.98 (95% confidence interval [CI]:0.28-4.81) and 2.10 (95% CI:0.77-5.71) among seasonal shift workers and continuous shift workers, respectively, compared with non-shift workers. In an age-stratified analysis (＜45 years vs.>45 years), the association between continuous shift work and diabetes mellitus was more pronounced among older participants. Compared with non-shift workers, the risk of diabetes mellitus was increased among continuous shift workers, whereas its effect is limited among seasonal shift workers.Acta medica Okayama 02/2013; 67(1):25-33. · 0.84 Impact Factor -
Article: Social and Geographical Inequalities in Suicide in Japan from 1975 through 2005: A Census-Based Longitudinal Analysis.
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ABSTRACT: Despite advances in our understanding of the countercyclical association between economic contraction and suicide, less is known about the levels of and changes in inequalities in suicide. The authors examined social and geographical inequalities in suicide in Japan from 1975 through 2005. Based on quinquennial vital statistics and census data, the authors analyzed the entire population aged 25-64 years. The total number of suicides was 75,840 men and 30,487 women. For each sex, the authors estimated odds ratios (ORs) and 95% credible intervals (CIs) for suicide using multilevel logistic regression models with "cells" (cross-tabulated by age and occupation) at level 1, seven different years at level 2, and 47 prefectures at level 3. Prefecture-level variance was used as an estimate of geographical inequalities in suicide. Adjusting for age and time-trends, the lowest odds for suicide was observed among production process and related workers (the reference group) in both sexes. The highest OR for men was 2.52 (95% CI: 2.43, 2.61) among service workers, whereas the highest OR for women was 9.24 (95% CI: 7.03, 12.13) among security workers. The degree of occupational inequalities increased among men with a striking change in the pattern. Among women, we observed a steady decline in suicide risk across all occupations, except for administrative and managerial workers and transport and communication workers. After adjusting for individual age, occupation, and time-trends, prefecture-specific ORs ranged from 0.76 (Nara Prefecture) to 1.36 (Akita Prefecture) for men and from 0.79 (Kanagawa Prefecture) to 1.22 (Akita Prefecture) for women. Geographical inequalities have increased primarily among men since 1995. The present findings demonstrate a striking temporal change in the pattern of social inequalities in suicide among men. Further, geographical inequalities in suicide have considerably increased across 47 prefectures, primarily among men, since 1995.PLoS ONE 01/2013; 8(5):e63443. · 4.09 Impact Factor -
Article: Progression-free survival and overall survival in phase III trials of molecular-targeted agents in advanced non-small-cell lung cancer.
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ABSTRACT: BACKGROUND: We examined how crossover therapy might affect the association between progression-free survival (PFS) and overall survival (OS) in non-small cell lung cancer (NSCLC). METHODS: We extracted PFS- and OS-hazard ratios (HRs) in phase III trials of molecular-targeted agents for advanced NSCLC. Their relationship was modeled in a linear function with the coefficient of determination (R-squared) to assess the correlation between PFS and OS. RESULTS: Thirty-four trials with 35 pairs for the investigational and reference arms were identified (24,158 patients). Overall, there was little correlation between PFS- and OS-HRs (R-squared=0.14), suggesting PFS-HR could account only for 14% of variation in OS-HR. The median proportion of crossover therapy per trial was 20%. If patients seldom crossed over (none or <1%), the association between PFS- and OS-HRs was strong (R-squared=0.69). When the proportion of crossover was ≥1%, however, R-squared declined considerably (≥1% to <20% crossover, R-squared=0.27; ≥20% to <40%, R-squared=0.06; and ≥40%, R-squared=0.27). CONCLUSIONS: A PFS advantage seldom is associated with an OS advantage any longer. Our analysis suggests this is due to a high level of crossover now that an increasing number of active agents are available for NSCLC.Lung cancer (Amsterdam, Netherlands) 11/2012; · 3.14 Impact Factor -
Article: Long working hours and metabolic syndrome among Japanese men: a cross-sectional study.
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ABSTRACT: The link between long working hours and health has been extensively studied for decades. Despite global concern regarding metabolic syndrome, however, no studies to date have solely evaluated the relationship between long working hours and that syndrome. We therefore examined the association between long working hours and metabolic syndrome in a cross-sectional study. Between May and October 2009, we collected data from annual health checkups and questionnaires from employees at a manufacturing company in Shizuoka, Japan. Questionnaires were returned by 1,601 workers (response rate: 96.2%; 1,314 men, 287 women). After exclusions, including women because of a lack of overtime work, the analysis was performed for 933 men. We calculated odds ratios (ORs) and 95% confidence intervals (CIs) for metabolic syndrome. Further, we conducted a stratified analysis by age-group (<40 years vs. ≥ 40 years). Metabolic syndrome was identified in 110 workers (11.8%). We observed a positive association between working hours and metabolic syndrome after adjusting for age, occupation, shift work, smoking status, frequency of alcohol consumption, and cohabiting status. Compared with subjects who worked 7-8 h/day, multivariate ORs for metabolic syndrome were 1.66 (95% CI, 0.91-3.01), 1.48 (95% CI, 0.75-2.90), and 2.32 (95% CI, 1.04-5.16) for those working 8-9 h/day, 9-10 h/day, and >10 h/day, respectively. Similar patterns were obtained when we excluded shift workers from the analysis. In age-stratified analysis, the corresponding ORs among workers aged ≥ 40 years were 2.02 (95% CI, 1.04-3.90), 1.21 (95% CI, 0.53-2.77), and 3.14 (95% CI, 1.24-7.95). In contrast, no clear association was found among workers aged <40 years. The present study suggests that 10 h/day may be a trigger level of working hours for increased risk of metabolic syndrome among Japanese male workers.BMC Public Health 05/2012; 12:395. · 2.00 Impact Factor -
Article: Workplace social capital and risk of chronic and severe hypertension: a cohort study.
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ABSTRACT: The association between workplace factors and the development of hypertension remains uncertain. We examined the risk of hypertension as a function of workplace social capital, that is, social cohesion, trust and reciprocity in the workplace. A total of 11 777 male and 49 145 female employees free of chronic hypertension at baseline in 2000-2004 were followed up for incident hypertension until the end of 2005 (the Finnish Public Sector Study). We used survey responses from the participants and their coworkers in the same work unit to assess workplace social capital at baseline. Follow-up for incident hypertension was based on record linkage to national health registers (mean follow-up 3.5 years, 1424 incident hypertension cases). Male employees in work units characterized by low workplace social capital were 40-60% more likely to develop chronic hypertension compared to men in work units with high social capital [age-adjusted hazard ratio 1.57, 95% confidence interval (CI) 1.15-2.14 for self-assessed social capital and 1.41, 95% CI 1.01-1.97 for coworkers' assessment]. According to path analysis adjusted for covariates, the association between low self-reported social capital and hypertension was partially mediated by obesity (P for pathway = 0.02) and alcohol consumption (P = 0.03). For coworker-assessed social capital, the corresponding mediation pathways did not reach statistical significance (P = 0.055 and 0.22, respectively). No association between workplace social capital and hypertension was found for women. These data suggest that low self-reported workplace social capital is associated with increased near-term risk of hypertension in men in part due to unhealthy lifestyle.Journal of hypertension 04/2012; 30(6):1129-36. · 4.02 Impact Factor -
Article: On the relations between excess fraction, attributable fraction, and etiologic fraction.
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ABSTRACT: It has been noted that there is ambiguity in the expression "attributable fraction," and epidemiologic literature has drawn a distinction between "excess fraction" and "etiologic fraction." These quantities do not necessarily approximate one another, and the etiologic fraction is not generally estimable without strong biologic assumptions. In previous studies, researchers have explained the relations between excess and etiologic fractions in the potential-outcome framework, and few authors have explained the relations between these concepts by showing the correspondence between the potential-outcome model and the sufficient-cause model. In this article, the authors thoroughly clarify the conceptual relations between excess, attributable, and etiologic fractions by explicating the correspondence between these 2 models. In so doing, the authors take into account the potential completion time of each sufficient cause, which contributes to further insight to clarify the 2 types of etiologic fraction, i.e., accelerating etiologic proportion and total etiologic proportion. These 2 measures cannot be distinguished in epidemiologic data, and the differences might be subtle. However, they are closely related to a very fundamental issue of causal inference, that is, how researchers define etiology. Further, the authors clarify the relation between 3 distinct assumptions-positive monotonicity, no preventive action (or sufficient-cause positive monotonicity), and no preventive sequence.American journal of epidemiology 02/2012; 175(6):567-75. · 5.59 Impact Factor -
Article: Does open-air exposure to volatile organic compounds near a plastic recycling factory cause health effects?
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ABSTRACT: After a plastic reprocessing factory began to operate in August 2004, the residents around the factory in Neyagawa, Osaka, Japan, began to complain of symptoms. Therefore, we conducted an exposure assessment and a population-based epidemiological study in 2006. To assess exposure, volatile organic compounds (VOCs) and total VOCs were measured at two locations in the vicinity of the factory. In the population-based study, a total of 3,950 residents were targeted. A self-administered questionnaire was used to collect information about subjects' mucocutaneous or respiratory symptoms. Using logistic regression models, we compared the prevalence of symptoms in July 2006 by employing the farthest area from the factory as a reference, and prevalence odds ratios (PORs) and their 95% confidence intervals (CIs) were estimated. The concentration of total VOCs was higher in the vicinity of the factory. The prevalence of mucocutaneous and respiratory symptoms was the highest among the residents in the closest area to the factory. Some symptoms were significantly increased among the residents within 500 m of the factory compared with residents of an area 2800 m from the factory: e.g., sore throat (POR=3.2, 95% CI: 1.3-8.0), eye itch (POR=3.0, 95% CI: 1.5-6.0), eye discharge (POR=6.0, 95% CI: 2.3-15.9), eczema (POR=3.0, 95% CI: 1.1-7.9) and sputum (POR=2.4, 95% CI: 1.1-5.1). Despite of the limitations of this study, these results imply a possible association of open-air VOCs with mucocutaneous and respiratory symptoms. Because this kind of plasticre cycling factory only recently came into operation, more attention should be paid to the operation of plastic recycling factories in the environment.Journal of Occupational Health 01/2012; 54(2):79-87. · 1.55 Impact Factor -
Article: Geographic inequalities in all-cause mortality in Japan: compositional or contextual?
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ABSTRACT: A recent study from Japan suggested that geographic inequalities in all-cause premature adult mortality have increased since 1995 in both sexes even after adjusting for individual age and occupation in 47 prefectures. Such variations can arise from compositional effects as well as contextual effects. In this study, we sought to further examine the emerging geographic inequalities in all-cause mortality, by exploring the relative contribution of composition and context in each prefecture. We used the 2005 vital statistics and census data among those aged 25 or older. The total number of decedents was 524,785 men and 455,863 women. We estimated gender-specific two-level logistic regression to model mortality risk as a function of age, occupation, and residence in 47 prefectures. Prefecture-level variance was used as an estimate of geographic inequalities in mortality, and prefectures were ranked by odds ratios (ORs), with the reference being the grand mean of all prefectures (value = 1). Overall, the degree of geographic inequalities was more pronounced when we did not account for the composition (i.e., age and occupation) in each prefecture. Even after adjusting for the composition, however, substantial differences remained in mortality risk across prefectures with ORs ranging from 0.870 (Okinawa) to 1.190 (Aomori) for men and from 0.864 (Shimane) to 1.132 (Aichi) for women. In some prefectures (e.g., Aomori), adjustment for composition showed little change in ORs, while we observed substantial attenuation in ORs in other prefectures (e.g., Akita). We also observed qualitative changes in some prefectures (e.g., Tokyo). No clear associations were observed between prefecture-level socioeconomic status variables and the risk of mortality in either sex. Geographic disparities in mortality across prefectures are quite substantial and cannot be fully explained by differences in population composition. The relative contribution of composition and context to health inequalities considerably vary across prefectures.PLoS ONE 01/2012; 7(6):e39876. · 4.09 Impact Factor -
Article: Social and geographic inequalities in premature adult mortality in Japan: a multilevel observational study from 1970 to 2005.
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ABSTRACT: To examine trends in social and geographic inequalities in all-cause premature adult mortality in Japan. Observational study of the vital statistics and the census data. Japan. Entire population aged 25 years or older and less than 65 years in 1970, 1975, 1980, 1985, 1990, 1995, 2000 and 2005. The total number of decedents was 984 022 and 532 223 in men and women, respectively. For each sex, ORs and 95% CIs for mortality were estimated by using multilevel logistic regression models with 'cells' (cross-tabulated by age and occupation) at level 1, 8 years at level 2 and 47 prefectures at level 3. The prefecture-level variance was used as an estimate of geographic inequalities of mortality. Adjusting for age and time-trends, compared with production process and related workers, ORs ranged from 0.97 (95% CI 0.96 to 0.98) among administrative and managerial workers to 2.22 (95% CI 2.19 to 2.24) among service workers in men. By contrast, in women, the lowest odds for mortality was observed among production process and related workers (reference), while the highest OR was 12.22 (95% CI 11.40 to 13.10) among security workers. The degree of occupational inequality increased in both sexes. Higher occupational groups did not experience reductions in mortality throughout the period and was overtaken by lower occupational groups in the early 1990s, among men. Conditional on individual age and occupation, overall geographic inequalities of mortality were relatively small in both sexes; the ORs ranged from 0.87 (Okinawa) to 1.13 (Aomori) for men and from 0.84 (Kanagawa) to 1.11 (Kagoshima) for women, even though there is a suggestion of increasing inequalities across prefectures since 1995 in both sexes. The present findings suggest that both social and geographic inequalities in all-cause mortality have increased in Japan during the last 3 decades.BMJ open. 01/2012; 2(2):e000425. -
Article: Association between proximity to a health center and early childhood mortality in Madagascar.
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ABSTRACT: To evaluate the association between proximity to a health center and early childhood mortality in Madagascar, and to assess the influence of household wealth, maternal educational attainment, and maternal health on the effects of distance. From birth records of subjects in the Demographic and Health Survey, we identified 12565 singleton births from January 2004 to August 2009. After excluding 220 births that lacked global positioning system information for exposure assessment, odds ratios (ORs) and their 95% confidence intervals (CIs) for neonatal mortality and infant mortality were estimated using multilevel logistic regression models, with 12345 subjects (level 1), nested within 584 village locations (level 2), and in turn nested within 22 regions (level 3). We additionally stratified the subjects by the birth order. We estimated predicted probabilities of each outcome by a three-level model including cross-level interactions between proximity to a health center and household wealth, maternal educational attainment, and maternal anemia. Compared with those who lived >1.5-3.0 km from a health center, the risks for neonatal mortality and infant mortality tended to increase among those who lived further than 5.0 km from a health center; the adjusted ORs for neonatal mortality and infant mortality for those who lived >5.0-10.0 km away from a health center were 1.36 (95% CI: 0.92-2.01) and 1.42 (95% CI: 1.06-1.90), respectively. The positive associations were more pronounced among the second or later child. The distance effects were not modified by household wealth status, maternal educational attainment, or maternal health status. Our study suggests that distance from a health center is a risk factor for early childhood mortality (primarily, infant mortality) in Madagascar by using a large-scale nationally representative dataset. The accessibility to health care in remote areas would be a key factor to achieve better infant health.PLoS ONE 01/2012; 7(6):e38370. · 4.09 Impact Factor -
Article: Clarifying the Use of Aggregated Exposures in Multilevel Models: Self-Included vs. Self-Excluded Measures.
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ABSTRACT: Multilevel analyses are ideally suited to assess the effects of ecological (higher level) and individual (lower level) exposure variables simultaneously. In applying such analyses to measures of ecologies in epidemiological studies, individual variables are usually aggregated into the higher level unit. Typically, the aggregated measure includes responses of every individual belonging to that group (i.e. it constitutes a self-included measure). More recently, researchers have developed an aggregate measure which excludes the response of the individual to whom the aggregate measure is linked (i.e. a self-excluded measure). In this study, we clarify the substantive and technical properties of these two measures when they are used as exposures in multilevel models. Although the differences between the two aggregated measures are mathematically subtle, distinguishing between them is important in terms of the specific scientific questions to be addressed. We then show how these measures can be used in two distinct types of multilevel models-self-included model and self-excluded model-and interpret the parameters in each model by imposing hypothetical interventions. The concept is tested on empirical data of workplace social capital and employees' systolic blood pressure. Researchers assume group-level interventions when using a self-included model, and individual-level interventions when using a self-excluded model. Analytical re-parameterizations of these two models highlight their differences in parameter interpretation. Cluster-mean centered self-included models enable researchers to decompose the collective effect into its within- and between-group components. The benefit of cluster-mean centering procedure is further discussed in terms of hypothetical interventions. When investigating the potential roles of aggregated variables, researchers should carefully explore which type of model-self-included or self-excluded-is suitable for a given situation, particularly when group sizes are relatively small.PLoS ONE 01/2012; 7(12):e51717. · 4.09 Impact Factor -
Article: Maternal working hours and early childhood overweight in Japan: a population-based study.
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ABSTRACT: There has been a growing concern that maternal employment could have adverse or beneficial effects on children's health. Although recent studies demonstrated that maternal employment was associated with a higher risk of childhood overweight, the evidence remains sparse in Asian countries. We sought to examine the relationship between maternal working hours and early childhood overweight in a rural town in Okayama Prefecture. In February 2008, questionnaires were sent to parents of all preschool children aged ≥3 yr in the town to assess maternal working status (working hours and form of employment), children's body mass index, and potential confounders. Childhood overweight was defined following the age and sex-specific criteria of the International Obesity Task Force. Odds ratios (ORs) and 95% confidence intervals (CIs) for childhood overweight were estimated in a logistic regression. We used generalized estimating equations with an exchangeable correlation matrix, considering the correlation between siblings. We analyzed 364 preschool children. Adjusting for each child's characteristics (age, sex), mother's characteristics (age, obesity, educational attainment, smoking status, and social participation), and family's characteristics (number of siblings), children whose mothers work <8 h/day had a substantially lower risk for being overweight (OR: 0.28, 95% CI: 0.09, 0.93) compared with children of non-working mothers, whereas the relationship was less pronounced among children whose mothers work ≥8 h/day (OR: 0.71, 95% CI: 0.19, 2.68). We observed similar patterns in a stratified analysis by the form of maternal employment. Short maternal working hours are associated with a lower odds of early childhood overweight.Journal of Occupational Health 12/2011; 54(1):25-33. · 1.55 Impact Factor -
Article: The usefulness of pre-radiofrequency ablation SUV(max) in 18F-FDG PET/CT to predict the risk of a local recurrence of malignant lung tumors after lung radiofrequency ablation.
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ABSTRACT: The aim of the present study was to assess the diagnostic usefulness of Fluorine-18 fluorodeoxyglucose (18F-FDG) positron emission tomography/computed tomography (PET/CT) in the prediction of local recurrence of malignant lung tumors by analyzing the pre-radiofrequency ablation (RFA) maximal standardized uptake value (SUV(max)). We performed a historical cohort study of consecutive malignant lung tumors treated by RFA from January 2007 to May 2008 at Okayama University Hospital. We selected only lung tumors examined by PET/CT within 90 days before RFA and divided them (10 primary and 29 metastatic) into 3 groups according to their tertiles of SUV(max). We calculated recurrence odds ratios in the medium group and the high group compared to the low group using multivariate logistic analysis. After we examined the relationship between SUV(max) and recurrence in a crude model, we adjusted for some factors. Tumors with higher SUV(max) showed higher recurrence odds ratios (medium group; 1.84, high group; 4.14, respectively). The tumor size also increased the recurrence odds ratio (2.67); we thought this was mainly due to selection bias because we excluded tumors less than 10mm in diameter. This study demonstrated the pre-RFA SUV(max) in PET/CT may be a prognostic factor for local recurrence of malignant lung tumors.Acta medica Okayama 12/2011; 65(6):395-402. · 0.84 Impact Factor -
Article: Social capital and self-rated oral health among young people.
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ABSTRACT: A few studies have revealed the impact of neighborhood social capital on oral health among young people. We sought to examine the associations of social capital in three settings (families, neighborhoods, and schools) with self-rated oral health among a sample of college students in Japan. Cross-sectional survey of 967 students in Okayama University, aged 18 and 19 years, was carried out. Logistic regression was used to examine the associations of poor self-rated oral health with perceptions of social capital, adjusting for self-perceived household income category and oral health behaviors. The prevalence of subjects with poor self-rated oral health was 22%. Adjusted for gender, self-perceived household income category, dental fear, toothbrush frequency, and dental floss use, poor self-rated oral health was significantly associated with lower level of neighborhood trust [odds ratio (OR) 2.22; 95% confidence interval (CI): 1.40-3.54] and lower level of vertical trust in school (OR 1.71; 95% CI: 1.05-2.80). Low informal social control was unexpectedly associated with better oral health (OR 0.54; 95% CI: 0.34-0.85). The association of social capital with self-rated oral health is not uniform. Higher trust is associated with better oral health, whereas higher informal control in the community is associated with worse oral health.Community Dentistry And Oral Epidemiology 10/2011; 40(2):97-104. · 1.89 Impact Factor -
Article: Workplace social capital and all-cause mortality: a prospective cohort study of 28,043 public-sector employees in Finland.
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ABSTRACT: We examined the association between workplace social capital and all-cause mortality in a large occupational cohort from Finland. We linked responses of 28 043 participants to surveys in 2000 to 2002 and in 2004 to national mortality registers through 2009. We used repeated measurements of self- and coworker-assessed social capital. We carried out Cox proportional hazard and fixed-effects logistic regressions. During the 5-year follow-up, 196 employees died. A 1-unit increase in the mean of repeat measurements of self-assessed workplace social capital (range 1-5) was associated with a 19% decrease in the risk of all-cause mortality (age- and gender-adjusted hazard ratio [HR] = 0.81; 95% confidence interval [CI] = 0.66, 0.99). The corresponding point estimate for the mean of coworker-assessed social capital was similar, although the association was less precisely estimated (age- and gender-adjusted HR = 0.77; 95% CI = 0.50, 1.20). In fixed-effects analysis, a 1-unit increase in self-assessed social capital across the 2 time points was associated with a lower mortality risk (odds ratio = 0.81; 95% CI = 0.55, 1.19). Workplace social capital appears to be associated with lowered mortality in the working-aged population.American Journal of Public Health 09/2011; 101(9):1742-8. · 3.93 Impact Factor -
Article: Outbreak of Salmonella Braenderup infection originating in boxed lunches in Japan in 2008.
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ABSTRACT: There have been only 2 reports of a large-scale foodborne outbreak arising from Salmonella enterica serotype Braenderup infection worldwide. On August 9, 2008, an outbreak originating in boxed lunches occurred in Okayama, Japan. We conducted a cohort study of 786 people who received boxed lunches from a particular catering company and collected 644 questionnaires (response rate:82%). Cases were defined as those presenting with diarrhea (≧4 times in 24h) or fever (≧38℃) between 12 am on August 8 and 12 am on August 14. We identified 176 cases (women/men:39/137);younger children (aged＜10 years) appeared to more frequently suffer severe symptoms. Three food items were significantly associated with higher risk of illness;tamagotoji (soft egg with mixed vegetables and meat) (relative risk (RR):11.74, 95% confidence interval (CI):2.98-46.24), pork cooked in soy sauce (RR:3.17, 95% CI:1.24-8.10), and vinegared food (RR:4.13, 95% CI:1.60-10.63). Among them, only the RR of tamagotoji was higher when we employed a stricter case definition. Salmonella Braenderup was isolated from 5 of 9 sampled cases and 6 food handlers. It is likely that unpasteurized liquid eggs contaminated by Salmonella Braenderup and used in tamagotoji caused this outbreak.Acta medica Okayama 04/2011; 65(2):63-9. · 0.84 Impact Factor -
Article: Environmental factors and seasonal influenza onset in Okayama city, Japan: case-crossover study.
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ABSTRACT: Seasonal influenza infection is a major challenge in public health. The term "seasonal influenza" refers to the typical increase in the number of influenza patients in the winter season in temperature zones. However, it is not clear how environmental factors within a single flu season affect influenza infection in a human population. Therefore, we evaluated the effects of temperature and humidity in the 2006-7 flu season on the onset of seasonal influenza using a case-crossover study. We targeted patients who attended one pediatric clinic in Okayama city, Japan and who were diagnosed as being infected with the seasonal influenza virus. Using 2 references (time-stratified and symmetric bidirectional design), we estimated the effects of average temperature and relative humidity from the onset day (lag0) to 10 days before (lag10). The total number of subjects was 419, and their onset days ranged from 26 December 2006 to 30 April 2007. While the onset was significantly associated with lower temperature, relative humidity was not related. In particular, temperatures before the 3-day incubation period had higher-magnitude odds ratios. For example, the odds ratio and 95% confidence interval for average temperature at time lag 8 was 1.12 (1.08-1.17) per 1.0℃ decrease. Low environmental temperature significantly increased the risk of seasonal influenza onset within the 2006-7 winter season.Acta medica Okayama 04/2011; 65(2):97-103. · 0.84 Impact Factor -
Article: Identification of operating mediation and mechanism in the sufficient-component cause framework.
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ABSTRACT: The assessment of mediation and mechanism is one way to more deeply explore cause-effect relationships, providing a stronger test and explanation of the observed associations. Most previous studies have described direct and indirect effects in terms of potential outcomes and response types, exploring mediation analysis in the counterfactual (= potential-outcome) framework. A recent paper by Hafeman (Eur J Epidemiol 23(11):711-721, 2008) provided a conceptual description of mediation in the sufficient-component cause framework, and VanderWeele (Eur J Epidemiol 24(5):217-224, 2009) explored the distinctions and relationships between the concepts of mediation and mechanism. This study builds on this prior work and demonstrates that further insight can be given by elucidating the concepts of mediation and mechanism in the sufficient-component cause framework, distinguishing their operation from presence. The careful consideration of the concepts of mediation and mechanism can clarify the relationship between them. Then, the present article describes how investigators can identify mediation as well as mechanism by showing their correspondence with direct and indirect effects in the counterfactual framework. This study also demonstrates how a researcher can decompose the total effect into the effect due to mediated paths and the effect due to non-mediated paths in terms of the probabilities of background factors of sufficient causes.European Journal of Epidemiology 03/2011; 26(5):347-57. · 4.71 Impact Factor -
Article: The local efficacy of I-131 for F-18 FDG PET positive lesions in patients with recurrent or metastatic thyroid carcinomas.
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ABSTRACT: The aim of this study was to evaluate the local efficacy of I-131 for F-18 fluorodeoxyglucose positron emission tomography (FDG PET)-positive lesions. Whole-body FDG PET/CT was performed on 37 patients (55 cases: 16 men, 21 women; age range: 24-82 years; mean age ± standard deviation: 60.5 ± 16.0 years) with differentiated thyroid cancer after total thyroidectomy. The metastatic or recurrent lesions were divided into 5 categories: primary tumor bed, lymph node, lung, bone, and other. The well-defined lesions were measured on CT, and the sizes were compared before and after radioactive iodine therapy. The analysis was performed on 37 patients with 44 lesions (lymph node:24, lung:16, bone:4). Sixteen lesions (70%) were increased and 7 (30%) showed no change or reduction when there was positive accumulation on FDG PET/CT and negative accumulation on I-131 (F(+)I(-)) group. In the positive accumulation for both FDG PET/CT and I-131 (F(+)I(+)) group, 5 lesions (63%) were increased and 3 (37%) showed no change or reduction. There was no significant difference for the tendency to increase in size between the F(+)I(-) and the F(+)I(+) groups. Lesions which show positive accumulations on FDG PET/CT have a greater tendency to increase in size. FDG-avid lesions are resistant to radioactive iodine therapy with or without I-131 uptake.Clinical nuclear medicine 02/2011; 36(2):113-7. · 3.92 Impact Factor
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2008–2013
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Okayama University
- Department of Epidemiology
Okayama-shi, Okayama-ken, Japan
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