Yuko Kachi

Precarious employment and the risk of serious psychological distress: a population-based cohort study in Japan.

OBJECTIVES This study examines whether precarious employment increases the risk of serious psychological distress (SPD) in a nationally representative cohort of Japanese middle-aged people. METHODS From 2005-2009, we followed 8486 male and 6736 female participants (aged 50-59 years) in the Longitudinal Survey of Middle-aged and Elderly Persons. All individuals were employed and free of SPD, cardiovascular disease, and cancer at baseline. The participants were classified into two groups based on their baseline employment contract: precarious and full-time permanent work. SPD was assessed at each year during the study, using the K6 scale, a self-rated 6-item scale that screens for mood or anxiety disorders. We used discrete-time survival analysis, with a complementary log-log link, to examine the effect of precarious employment on SPD incidence. RESULTS During a maximum follow-up period of four years, 374 men and 364 women developed SPD. Male precarious employees were more likely to develop SPD than male full-time permanent employees (hazard ratio 1.79, 95% confidence interval 1.28-2.51) in the full model, after adjusting for sociodemographic and occupational factors, cardiovascular disease risk, and K6 scores at baseline. By contrast, no significant association was observed among female employees. However, an analysis stratified by marital status revealed an association similar to that found among men but only among unmarried women. CONCLUSIONS The findings suggest that precarious employment is associated with double the risk of SPD incidence among middle-aged Japanese men and - when stratified by marital status - among unmarried women. This highlights a major gender difference in the association between precarious employment and risk of SPD.

Association of sleep duration with untreated diabetes in Japanese men

OBJECTIVE We assessed the cross-sectional association between sleep duration and untreated diabetes in Japanese men. METHODS Participants included 20,744 men aged 30-64 years who first visited the general hospital in Tokyo for routine health assessments during 2003-2007. Untreated diabetes was defined as not being under diabetes treatment and fasting blood glucose of ≥126 mg/dL or hemoglobin A(1c) of ≥6.5%. Sleep duration (≤5, 6, 7, or ≥8 h) and confounders were assessed using a questionnaire. Logistic regression was used to calculate odds ratios (ORs) for diabetes after adjustment for confounders. RESULTS The prevalence of untreated diabetes was 3.4% in all men. The prevalence of untreated diabetes by sleep duration was as follows: ≤5 h: 3.5%; 6 h: 3.3%; 7 h: 3.2%; and ≥8 h: 5.1%. Men who reported sleeping for ≤5 h (OR: 1.52, 95% confidential interval [CI]: 1.22-1.90) and ≥8 h (OR: 1.39, 95% CI: 1.05-1.85) were significantly more likely to have untreated diabetes compared with those who reported sleeping for 7 h. In stratified analyses by obesity (body mass index ≥25.0 kg/m(2)), the association between long sleep duration (≥8 h) and untreated diabetes remained significant only in obese men. CONCLUSION Short sleep duration was significantly associated with untreated diabetes in both nonobese and obese men. Regarding long sleep duration, a significant association was observed in obese men only.

Determinants of changes in income-related health inequalities among working-age adults in Japan, 1986-2007: Time-trend study

This study aimed to quantify the contributions of the factors that have influenced changes in income-related health inequalities. We used data from a nationally representative sample of Japanese men and women aged 20-59 years who participated in eight repeated cross-sectional surveys between 1986 and 2007. A concentration index (CI) was used to measure income-related inequalities in self-rated health (SRH) and decomposed into contributing factors. We then examined temporal changes in CIs and their contributing factors. Results showed that income-related inequalities in SRH, unfavourable to low-income groups, persisted throughout the study period. Despite widening income inequalities, inequalities in SRH narrowed during the period of economic stagnation since the late 1990s because of the profound deterioration in SRH among middle- to high-income groups. Decomposition analysis showed that income itself and unemployment or economic inactivity were the most important contributors to inequalities in SRH for both sexes at almost all time points. However, from 1986 to 2007, the relative contribution of income to these inequalities decreased from 78% to 14% in men and from 85% to 38% in women. By contrast, the relative contribution of unemployment or economic inactivity increased from 18% to 77% in men and from 10% to 31% in women. Our results suggest that a reduction in avoidable health inequalities could be achieved by reducing the influence of unemployment or economic inactivity on health.

Association of metabolic syndrome with atypical features of depression in Japanese people

It has been controversial whether metabolic syndrome (MetS) is associated with depression. We aimed to clarify the correlation between MetS and depression, considering atypical features of depression.

Development of a risk prediction model for incident hypertension in a working-age Japanese male population

The aim of this study was to develop a risk prediction model for incident hypertension in a Japanese male population. Study participants included 15 025 nonhypertensive Japanese male workers (mean age, 38.8±8.9 years) who underwent an annual medical checkup at a company. The participants were followed-up for a median of 4.0 years to determine new-onset hypertension, defined as a systolic blood pressure (BP) ⩾140 mm Hg, a diastolic BP ⩾90 mm Hg, or the initiation of antihypertensive medication. Participants were divided into the following two cohorts for subsequent analyses: the derivation cohort (n=12 020, 80% of the study population) and the validation cohort (n=3005, the remaining 20% of the study population). In the derivation cohort, a multivariate Cox proportional hazards model demonstrated that age, body mass index, systolic and diastolic BP, current smoking status, excessive alcohol intake and parental history of hypertension were independent predictors of incident hypertension. Using these variables, a risk prediction model was constructed to estimate the 4-year risk of incident hypertension. In the validation cohort, the risk prediction model demonstrated high discrimination ability and acceptable calibration, with a C-statistic of 0.861 (95% confidence interval 0.844, 0.877) and a modified Hosmer–Lemeshow χ2 statistic of 15.2 (P=0.085). A risk score sheet was constructed to enable the simple calculation of the approximate 4-year probability of incident hypertension. In conclusion, a practical risk prediction model for incident hypertension was successfully developed in a working-age Japanese male population.

Socioeconomic Status and Overweight: A Population-Based Cross-Sectional Study of Japanese Children and Adolescents

Background Socioeconomic status (SES) as a determinant of obesity has received scant attention in Japan. This study examined the association between SES and overweight among Japanese children and adolescents. Methods Cross-sectional analyses of a representative sample of Japanese children (6–11 years: n = 397) and adolescents (12–18 years: n = 397) were performed, with measured heights and weights from the 2010 National Health and Nutrition Examination Survey and the 2010 Comprehensive Survey of Living Conditions. Overweight, including obesity, was defined by International Obesity Task Force cut-offs. SES indicators included household income, equivalent household expenditure, parental educational attainment, and parental occupational class. Results Overweight prevalence was 12.3% in children and 9.1% in adolescents. Adolescents living in middle-income households were more likely to be overweight than those living in high-income households (OR 2.26, 95% CI, 1.01–5.67) after adjustment for age, sex, and parental weight status. Similarly, adolescents living in households with low expenditure levels were more likely to be overweight than those living in households with high expenditure levels (OR 3.40, 95% CI, 1.20–9.60). In contrast, no significant association was observed among children. Conclusions Our results indicated that low household economic status was associated with being overweight, independent of parental weight status, among Japanese adolescents.

Differences in Self-rated Health by Employment Contract and Household Structure among Japanese Employees: A Nationwide Cross-sectional Study

Differences in Self‐rated Health by Employment Contract and Household Structure among Japanese Employees: A Nationwide Cross‐Sectional Study: Yuko KACHI, et al. Department of Hygiene and Public Health, Nippon Medical School—

Association between insomnia symptoms and hemoglobin A1c level in Japanese men.

Background The evidence for an association between insomnia symptoms and blood hemoglobin A1c (HbA1c) level has been limited and inconclusive. The aim of this study was to assess whether each symptom of initial, middle, and terminal insomnia influences HbA1c level in Japanese men. Methods This cross-sectional study examined 1,022 male workers aged 22–69 years with no history of diabetes at a Japanese companys annual health check-up in April 2010. High HbA1c was defined as a blood level of HbA1c ≥6.0%. Three types of insomnia symptoms (i.e., difficulty in initiating sleep, difficulty in maintaining sleep, and early morning awakening) from the previous month were assessed by 3 responses (i.e., lasting more than 2 weeks, sometimes, and seldom or never [reference group]). Results The overall prevalence of high HbA1c was 5.2%. High HbA1c was positively and linearly associated with both difficulty in maintaining sleep (P for trend  = .002) and early morning awakening (P for trend  = .007). More specifically, after adjusting for potential confounding factors, high HbA1c was significantly associated with difficulty in maintaining sleep lasting more than 2 weeks (adjusted odds ratio, 6.79 [95% confidence interval, 1.86–24.85]) or sometimes (2.33 [1.19–4.55]). High HbA1c was also significantly associated with early morning awakening lasting more than 2 weeks (3.96 [1.24–12.59]). Conclusion Insomnia symptoms, particularly difficulty in maintaining sleep and early morning awakening, were found to have a close association with high HbA1c in a dose-response relationship.

Serum Cystatin C, Creatinine-Based Estimated Glomerular Filtration Rate, and the Risk of Incident Hypertension in Middle-Aged Men

BACKGROUND The aim of this study was to examine the predictive value of serum cystatin C (CysC) and that of creatinine-based estimated glomerular filtration rate (eGFRCreat) for the risk of incident hypertension in a middle-aged male population. METHODS Serum CysC levels were measured in 904 nonhypertensive, Japanese male subjects (mean age = 44±6 years) who received an annual general health examination in a company. Serum creatinine levels were simultaneously measured, and eGFRCreat was calculated. Subjects were followed-up for a maximum period of 4 years, and annual blood pressure measurements were recorded. RESULTS During the follow-up period, 124 subjects developed hypertension, defined as systolic/diastolic blood pressure ≥140/90 mmHg or use of antihypertensive medications. In the Kaplan-Meier analysis, both the third quintile of CysC and that of eGFRCreat showed the lowest 4-year cumulative incident rate of hypertension. The multiadjusted hazard ratio for incident hypertension was significantly increased in the highest quintile of CysC compared with the third quintile (2.60; 95% confidence interval (CI) = 1.41-4.77; P = 0.002), as well as compared with the lowest 4 quintiles combined (1.89; 95% CI = 1.26-2.84; P = 0.002). However, eGFRCreat did not show significant hazard ratios for incident hypertension in any of the adjusted models. CONCLUSIONS Elevated serum CysC levels could predict the risk of incident hypertension in this study population with a maximum follow-up period of 4 years. In contrast, eGFRCreat did not show predictive value for the risk of incident hypertension.

Relationship between Dietary Factors and Prostate-Specific Antigen in Healthy Men

Introduction: There is little evidence indicating whether dietary factors influence prostate-specific antigen (PSA) concentrations. We examined whether nutritional factors, including energy, protein, fat, and carbohydrate intake were associated with PSA in healthy men. Subjects and Methods: We investigated 13,594 men aged 50 years and over who visited a hospital for a routine health checkup between 2003 and 2007. Dietary intake was assessed using a food frequency questionnaire. We performed a multiple linear regression to examine the association between PSA and dietary intake. Results: After controlling for age, body mass index, and physical activity, PSA was significantly negatively associated with percent protein intake (p for trend < 0.001). Compared with the lowest quintile, PSA was 5.8% lower (95% CI: –8.9 to –2.5%) in the highest quintile. We also observed a significant positive association between percent fat intake and PSA concentration (p for trend 0.043). PSA was 3.4% greater (95% CI: 0–6.9%) among men in the highest quintile compared with those in the lowest quintile. Conclusions: Men who had a lower percent protein intake and higher percent fat intake had an elevated PSA level, although the magnitude of these associations was small.