Chihiro Nishiura

A 4-Year Study of the Association between Short Sleep Duration and Change in Body Mass Index in Japanese Male Workers

Background Studies of Western populations have shown an inconsistent longitudinal association between short sleep duration and change in body mass index (BMI); a recent Japanese cohort study reported a significant association in men, but over a 1-year period. The aim of this longitudinal study was to examine whether this association was robust over a 4-year interval in Japanese men. Methods A total of 3803 middle-aged Japanese male white-collar workers (mean age 47.8 years, mean BMI 23.9 kg/m2) in Tokyo, Japan, were included in this study from 1994–1995 (baseline) to 1998–1999 (follow-up). Height and weight were objectively measured at annual health checkups, and other data, including sleep duration, were collected using a structured interview. We used linear regression models to estimate change in BMI, after adjustment for covariates. The reference category for sleep duration was set to 7 hours, to conform with previous studies. Results As compared with participants sleeping 7 hours, those sleeping 5 hours or less had a significantly higher BMI at baseline (beta coefficient: 0.34 kg/m2, 95% confidence interval (CI): 0.03, 0.65) and gained 0.15 kg/m2 in BMI over 4 years (95% CI: 0.03, 0.27), after adjustment for age, baseline BMI, lifestyle behavior, and medication. Conclusions The longitudinal association between short sleep duration at baseline and relative increase in BMI was significant in Japanese male workers over a 4-year interval.

Limitations on Work and Attendance Rates after Employees with Cancer Returned to Work at a Single Manufacturing Company in Japan

Limitations on Work and Attendance Rates after Employees with Cancer Returned to Work at a Single Manufacturing Company in Japan: Takayuki Ohguri, et al. Department of Radiology, University of Occupational and Environmental Health, Japan

Development of Risk Score for Predicting 3-Year Incidence of Type 2 Diabetes: Japan Epidemiology Collaboration on Occupational Health Study

Objective Risk models and scores have been developed to predict incidence of type 2 diabetes in Western populations, but their performance may differ when applied to non-Western populations. We developed and validated a risk score for predicting 3-year incidence of type 2 diabetes in a Japanese population. Methods Participants were 37,416 men and women, aged 30 or older, who received periodic health checkup in 2008–2009 in eight companies. Diabetes was defined as fasting plasma glucose (FPG) ≥126 mg/dl, random plasma glucose ≥200 mg/dl, glycated hemoglobin (HbA1c) ≥6.5%, or receiving medical treatment for diabetes. Risk scores on non-invasive and invasive models including FPG and HbA1c were developed using logistic regression in a derivation cohort and validated in the remaining cohort. Results The area under the curve (AUC) for the non-invasive model including age, sex, body mass index, waist circumference, hypertension, and smoking status was 0.717 (95% CI, 0.703–0.731). In the invasive model in which both FPG and HbA1c were added to the non-invasive model, AUC was increased to 0.893 (95% CI, 0.883–0.902). When the risk scores were applied to the validation cohort, AUCs (95% CI) for the non-invasive and invasive model were 0.734 (0.715–0.753) and 0.882 (0.868–0.895), respectively. Participants with a non-invasive score of ≥15 and invasive score of ≥19 were projected to have >20% and >50% risk, respectively, of developing type 2 diabetes within 3 years. Conclusions The simple risk score of the non-invasive model might be useful for predicting incident type 2 diabetes, and its predictive performance may be markedly improved by incorporating FPG and HbA1c.

Hba1c, Blood Pressure, and Lipid Control in People with Diabetes: Japan Epidemiology Collaboration on Occupational Health Study.

Aims The control of blood glucose levels, blood pressure (BP), and low-density lipoprotein cholesterol (LDL-C) levels reduces the risk of diabetes complications; however, data are scarce on control status of these factors among workers with diabetes. The present study aimed to estimate the prevalence of participants with diabetes who meet glycated hemoglobin (HbA1c), BP, and LDL-C recommendations, and to investigate correlates of poor glycemic control in a large working population in Japan. Methods The Japan Epidemiology Collaboration on Occupational Health (J-ECOH) Study is an ongoing cohort investigation, consisting mainly of employees in large manufacturing companies. We conducted a cross-sectional analysis of 3,070 employees with diabetes (2,854 men and 216 women) aged 20–69 years who attended periodic health examinations. BP was measured and recorded using different company protocols. Risk factor targets were defined using both American Diabetes Association (ADA) guidelines (HbA1c < 7.0%, BP < 140/90 mmHg, and LDL-C < 100 mg/dL) and Japan Diabetes Society (JDS) guidelines (HbA1c < 7.0%, BP < 130/80 mmHg, and LDL-C < 120 mg/dL). Logistic regression models were used to explore correlates of poor glycemic control (defined as HbA1c ≥ 8.0%). Results The percentages of participants who met ADA (and JDS) targets were 44.9% (44.9%) for HbA1c, 76.6% (36.3%) for BP, 27.1% (56.2%) for LDL-C, and 11.2% (10.8%) for simultaneous control of all three risk factors. Younger age, obesity, smoking, and uncontrolled dyslipidemia were associated with poor glycemic control. The adjusted odds ratio of poor glycemic control was 0.58 (95% confidence interval, 0.46–0.73) for participants with treated but uncontrolled hypertension, and 0.47 (0.33–0.66) for participants with treated and controlled hypertension, as compared with participants without hypertension. There was no significant difference in HbA1c levels between participants with treated but uncontrolled hypertension and those with treated and controlled hypertension. Conclusion Data from a large working population, predominantly composed of men, suggest that achievement of HbA1c, BP, and LDL-C targets was less than optimal, especially in younger participants. Uncontrolled dyslipidemia was associated with poor glycemic control. Participants not receiving antihypertensive treatment had higher HbA1c levels.

Smoking, Smoking Cessation, and the Risk of Type 2 Diabetes among Japanese Adults: Japan Epidemiology Collaboration on Occupational Health Study

Aims To examine the association of smoking status, smoking intensity, and smoking cessation with the risk of type 2 diabetes (T2D) using a large database. Methods The present study included 53,930 Japanese employees, aged 15 to 83 years, who received health check-up and did not have diabetes at baseline. Diabetes was defined as fasting plasma glucose ≥126 mg/dl, random plasma glucose ≥200 mg/dl, HbA1c ≥6.5% (≥48 mmol/mol), or receiving medication for diabetes. Cox proportional-hazards regression models were used to investigate the association between smoking and the risk of diabetes. Results During 3.9 years of median follow-up, 2,441 (4.5%) individuals developed T2D. The multivariable-adjusted hazard ratios (95% CI) for diabetes were 1 (reference), 1.16 (1.04 to 1.30) and 1.34 (1.22 to 1.48) for never smokers, former smokers, and current smokers, respectively. Diabetes risk increased with increasing numbers of cigarette consumption among current smokers (P for trend <0.001). Although the relative risk of diabetes was greater among subjects with lower BMIs (< 23 kg/m2), attributable risk was greater in subjects with higher BMIs (≥ 23 kg/m2). Compared with individuals who had never smoked, former smokers who quit less than 5 years, 5 to 9 years, and 10 years or more exhibited hazards ratios for diabetes of 1.36 (1.14 to 1.62), 1.23 (1.01 to 1.51), and 1.02 (0.85 to 1.23), respectively. Conclusions Results suggest that cigarette smoking is associated with an increased risk of T2D, which may decrease to the level of a never smoker after 10 years of smoking cessation.

The Effect of Smoking Prevalence at Worksites on Individual Cessation Behavior

The Effect of Smoking Prevalence at Worksites on Individual Cessation Behavior: Chihiro Nishiura, et al. Department of Safety and Health, Tokyo Gas Co., Ltd.

Returning to work after sick leave due to cancer: a 365-day cohort study of Japanese cancer survivors

PurposeMore employees are experiencing a cancer diagnosis during their working-age years, yet there have been no large-scale Japanese studies investigating sick leave due to cancer. We clarified differences in the cumulative partial and full return to work (RTW) rates between different cancer types among Japanese cancer survivors.MethodsData on Japanese employees who experienced an episode of sick leave due to clinically certified cancer diagnosed between 1 January 2000 and 31 December 2011 were obtained from an occupational health register. Subject outcomes within the 365-day period following their initial day of sick leave were utilized for this study. We investigated the cumulative partial/full and full RTW rates by using survival analysis with competing risks and predictors of time to RTW by a Fine-Gray proportional hazard regression model.ResultsOne thousand two hundred seventy-eight subjects (1033 males and 245 females) experienced their first episode of sick leave due to cancer during the 12-year follow-up period. Of the subjects, 47.1 % returned to work full time within 6 months of their initial day of sick leave absence, and 62.3 % by 12 months. The cumulative RTW rate varied significantly by cancer type. There were considerable differences in the range of cumulative full RTW rates between the two categories (“lower full RTW rate” groups (“lung,” “hepatic, pancreatic,” “esophageal,” and “blood” cancer groups) vs. “higher full RTW rate” groups (“gastric,” “intestinal,” “breast,” “female genital,” “male genital,” “urinary”): 6.3 to 14.3 % vs. 11.4 to 28.3 % at 60 days, 10.6 to 22.4 % vs. 27.0 to 50.0 % at 120 days, 21.3 to 34.7 % vs. 38.5 to 65.4 % at 180 days, 34.3 to 42.9 % vs. 66.0 to 79.5 % at 365 days). Additionally, older age may be associated with a longer time to full RTW.ConclusionsMore than half of the subjects returned to work full-time within the 365-day period following their initial day of sick leave, with cumulative RTW rates varying by cancer type. Older employees may require a longer time to full RTW.Implications of Cancer SurvivorsIt is very important for companies (especially small- and medium-sized companies) to establish and improve their RTW support system for cancer survivors, with knowledge that the median time to RTW is expected to be at least a few months.

Sleep Duration and Weight Gain: Reconsideration by Panel Data Analysis

Background Inconsistent findings in previous studies of the association between sleep duration and changes in body mass index (BMI) may be attributed to misclassification of sleep duration fluctuations over time and unmeasured confounders such as genetic factors. The aim of the present study was to overcome these failings by using repeated measurements and panel data analysis to examine the sleep-BMI association. Methods Panel data were derived by secondary use of the data from mandatory health checkups at a Japanese gas company. Male non-shift workers aged 19–39 years in 2007 were annually followed until 2010 (n = 1687, 6748 records). BMI was objectively measured, and sleep duration was self-reported. Results Compared with 7-hour sleepers, panel analysis with the population-averaged model showed a significant increase in BMI among 5-hour (0.11 kg/m2, P = 0.001), 6-hour (0.07 kg/m2, P = 0.038), and ≥8-hour (0.19 kg/m2, P = 0.009) sleepers. On the other hand, after adjustment for unobserved time-invariant confounders using the fixed-effects model, the magnitude of the association was considerably attenuated and no longer significant (5-hour, 0.07 kg/m2, P = 0.168; 6-hour, 0.02 kg/m2, P = 0.631; ≥8-hour sleepers, 0.06 kg/m2, P = 0.460). Conclusions The longitudinal association between sleep duration and changes in BMI may be upwardly biased by unobserved time-invariant confounders rather than misclassified sleep duration. The net effect of sleep duration on weight gain may therefore be less than previously believed.

Duration and degree of weight change and risk of incident diabetes: Japan Epidemiology Collaboration on Occupational Health Study

We prospectively examined diabetes risk in association with a summary measure of degree and duration of weight change. The study participants were 51,777 employees from multiple companies in Japan, who were aged 30-59years, free of diabetes at baseline, and followed up for 7years (2008-2015). Exposure was cumulative body mass index (BMI)-years, which was defined as the area of BMI units above or below baseline BMI during follow-up, and was treated as a time-dependent variable in the Cox proportional hazards regression models. During the 263,539 person-years of follow-up, 3465 participants developed diabetes. The adjusted hazard ratio (HR) of diabetes for a 1-unit increase in cumulative BMI-years was 1.11 (95% confidence interval (CI): 1.09, 1.12). The association was more pronounced among overweight (HR=1.11; 95% CI: 1.08, 1.14) and obese (HR=1.12; 95% CI: 1.08, 1.15) adults compared with normal- and under-weight (HR=1.07; 95% CI: 1.03, 1.11) adults (P for interaction of cumulative BMI-years X baseline BMI-group=0.002). The association of higher cumulative BMI-years with incident diabetes did not substantially differ by metabolic phenotype. The present results emphasize the importance of avoiding additional weight gain over an extended period of time for the prevention of type 2 diabetes, especially among overweight and obese adults, irrespective of metabolic health status.

Screening for Measles Vaccination in Young Japanese Non-healthcare Workers Through Self-reported History

Screening for Measles Vaccination in Young Japanese Non‐healthcare Workers Through Self‐reported History: Chihiro NISHIURA, et al. Department of Safety and Health, Tokyo Gas Co., Ltd.—