Diagnosis-specific Cumulative Incidence of Return-to-work, Resignation, and Death Among Long-term Sick-listed Employees: Findings From the Japan Epidemiology Collaboration on Occupational Health Study.

BACKGROUND: While it is essential to understand how long is sufficient for return-to-work when designing paid sick-leave systems, little attempt has been done to collect cause-specific information on when and how many of sickness absentees returned to work, became unemployed, or passed away. METHODS: We studied the first sick-leave episode of ≥30 consecutive days in those ≤55 years of age during 2012-2013 among employees of 11 Japanese private companies (n = 1,209), which were followed until 2017. Overall and disease-specific cumulative incidences of return-to-work, resignations, and deaths were estimated using competing risk analysis. RESULTS: During the 3.5-year period (follow-up rate: 99.9%), 1,014 returned to work, 167 became unemployed, and 27 died. Overall, return-to-work occurred within 1 year in 74.9% of all absentees and in 89.3% of those who successfully returned to work. Resignation occurred within 1 year in 8.7% of all absentees and in 62.9% of all subjects who resigned. According to ICD-10 chapters, the cumulative incidence of return-to-work ranged from 82.1% for mental disorders (F00-F99) to 95.3% for circulatory diseases (I00-I99). The cumulative incidence of return-to-work due to mental disorders ranged from 66.7% in schizophrenia (F20) to 95.8% in bipolar affective disorders (F31). Death was rarely observed except for cases of neoplasms (C00-D48), of which the cumulative incidence of death reached 14.2% by 1.5 years. CONCLUSION: Return-to-work and resignations occurred commonly within 1 year of sick leave among long-term sickness absentees in the Japanese private companies. Our findings may assist occupational physicians and employers in developing effective social protection schemes.

Age-, sex-, and diagnosis-specific incidence rate of medically certified long-term sick leave among private sector employees: The Japan Epidemiology Collaboration on Occupational Health (J-ECOH) study.

BACKGROUND: Long-term sick-leave is a major public health problem, but data on its incidence in Japan are scarce. We aimed to present reference data for long-term sick-leave among private sector employees in Japan. METHODS: The study population comprised employees of 12 companies that participated in the Japan Epidemiology Collaboration on Occupational Health Study. Details on medically certified sick-leave lasting ≥30 days were collected from each company. Age- and sex-specific incidence rate of sick-leave was calculated for the period of April 2012 to March 2014. RESULTS: A total of 1422 spells in men and 289 in women occurred during 162,989 and 30,645 person-years of observation, respectively. The three leading causes of sick-leave (percentage of total spells) were mental disorders (52%), neoplasms (12%), and injury (8%) for men; and mental disorders (35%), neoplasms (20%), and pregnancy-related disease (14%) for women. Incidence rate of sick-leave due to mental disorders was relatively high among men in their 20s-40s but tended to decrease with age among women. Incidence rate of sick-leave due to neoplasms started to increase after age 50 in men and after age 40 in women, making neoplasms the leading cause of sick-leave after age 50 for women and after age 60 for men and the second leading cause after age 40 for women and after age 50 for men. Pregnancy-related disease was the second leading cause of sick-leave among women aged 20-39 years. CONCLUSIONS: These results suggest that mental disorder, neoplasms, and pregnancy-related disease are the major causes of long-term sick-leave among private sector employees in Japan.

Comparison of body mass index, waist circumference, and waist-to-height ratio for predicting the clustering of cardiometabolic risk factors by age in Japanese workers--Japan Epidemiology Collaboration on Occupational Health study.

BACKGROUND: Waist-to-height ratio (WHtR) has been suggested as a better screening tool than body mass index (BMI) and waist circumference (WC) for assessing cardiometabolic risk. However, most previous studies did not consider age. METHODS AND RESULTS: Participants were 45,618 men and 8,092 women aged 15-84 years who received periodic health checkups in 9 companies in Japan. Clustering of cardiometabolic risk factors was defined by the existence of 2 or more of high blood pressure, hyperglycemia, and dyslipidemia. In both men and women, unadjusted area under the curve (AUC) of the receiver-operating characteristic curve for WHtR in detecting the clustering of cardiometabolic risk factors was significantly higher than that for either BMI or WC; the AUCs for WHtR, BMI, and WC, respectively, were 0.734, 0.705, and 0.717 in men and 0.782, 0.762, and 0.755 in women. After adjustment for age, however, such differences were not observed; the corresponding values were 0.702, 0.701, and 0.696 in men. In women, the age-adjusted AUC for BMI was slightly higher than for other indices (WHtR, 0.721; BMI, 0.726; WC, 0.707). CONCLUSIONS: The screening performance of WHtR for detecting the clustering cardiometabolic risk factors was not superior to that of BMI.

Effect of age, smoking and other lifestyle factors on urinary 7-methylguanine and 8-hydroxydeoxyguanosine.

Urinary 8-hydroxydeoxyguanosine (8-OH-dG) and 7-methylguanine (m7Gua) were measured by a column-switching high performance liquid chromatography method as markers of oxidative and methylating DNA damage, respectively. We investigated the associations between urinary 8-OH-dG or m7Gua and various lifestyle and demographic factors, such as age and sex. The urinary 8-OH-dG excretion level was positively correlated with cigarette smoking, but inversely correlated with fruit consumption, physical activity and total energy consumed per day. A multiple regression analysis revealed that daily physical activity and healthy meal combinations decreased the urinary 8-OH-dG level, whereas alcohol consumption increased it. In terms of the urinary m7Gua measurement, cigarette smoking, age and consumption of meat, fish, egg, soybean, etc. were positively correlated with the urinary m7Gua level, whereas body weight, BMI, physical activity, and dietary index score, which indicates good nutritional balance, were negatively correlated with the amount of m7Gua. Based on a multiple regression analysis, cigarette smoking and age correlated with the m7Gua level, while high BMI and healthy meal combinations have significant reducing effects on m7Gua level. Therefore, the urinary m7Gua level is considered to be a useful marker of DNA methylation, not only from smoking, but also from aging and unhealthy dietary habits.

Maternity blues as predictor of postpartum depression: a prospective cohort study among Japanese women.

BACKGROUND: Maternity blues and postpartum depression are common complications of childbearing. However, few studies have shown the relationship between the severity of maternity blues and the risk of postnatal depression. We carried out a longitudinal study among Japanese women to show that maternity blues is a useful factor for predicting postpartum depression. METHODS: Two hundred and thirty-five women completed questionnaires before delivery, and five days, one month, and three months after delivery. They were required to answer the Stein's Blues Scale and Edinburgh Postnatal Depression Scale and other variables. A sequential logistic regression analysis was performed to estimate the association of maternity blues with postpartum depression. The stratum-specific likelihood ratio was then calculated. RESULTS: The prevalence of postpartum depression was 12.8%. A Stein's Blues Scale of eight or above was significantly associated with postnatal depression. Likelihood ratios (95% CI ) for the Stein's Blues Scale of 0 to 3, 4 to 7, 8 to 11 and 12 or more were 0.33 (0.16-0.65), 1.06 (0.60-1.88), 3.42 (1.64-7.12) and 9.57 (3.41-26.86), respectively. CONCLUSIONS: These findings suggest that maternity blues is a strong predictor of postpartum depression. The higher the blues score, the higher the risk of postpartum depression.

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

[This corrects the article DOI: 10.1371/journal.pone.0142779.].

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.

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.

Effects of sleep hygiene education and behavioral therapy on sleep quality of white-collar workers: a randomized controlled trial.

Because poor sleep quality can reduce quality of life and increase prevalence of illness in workers, interventions are becoming increasingly important for businesses. To evaluate how sleep quality is affected by one-on-one behavioral modification when combined with group education, we conducted a randomized, controlled trial among day-shift white-collar employees working for an information-technology service company in Japan. Participants were randomly allocated to groups receiving either sleep hygiene group education (control group), or education combined with individual sleep modification training (one-on-one group). Occupational health professionals carried out both procedures, and sleep quality was assessed using the Pittsburgh Sleep Quality Index (PSQI). PSQI scores were obtained before and after the intervention period, and changes in scores were compared across groups after adjustments for age, gender, job title, smoking and drinking habits, body-mass index, and mental health as assessed using K6 scores. The average PSQI score for the control group decreased by 0.8, whereas that of the one-on-one group decreased by 1.8 (difference of 1), resulting in a significantly greater decrease in score for the one-on-one group (95% confidence interval: 0.02 to 2.0). These results show that, compared to sleep hygiene group education alone, the addition of individual behavioral training significantly improved the sleep quality of workers after only three months.

Randomized controlled trial on the effects of a combined sleep hygiene education and behavioral approach program on sleep quality in workers with insomnia.

To evaluate the effects of a combined sleep hygiene education and behavioral approach program on sleep quality in workers with insomnia, we conducted a randomized controlled trial at a design engineering unit in Japan. Employees evaluated for insomnia by the Athens Insomnia Scale (≥6 points) were divided into an intervention and control group. The intervention group received a short-term intervention (30 min) program that included sleep hygiene education and behavioral approaches (relaxation training, stimulus control, and sleep restriction) performed by occupational health professionals. We calculated differences in change in Pittsburgh Sleep Quality Index (PSQI) scores between the two groups from baseline to three months after the start of intervention after adjusting for gender, age, job title, job category, average number of hours of overtime during the study period, marital status, smoking habit, average number of days of alcohol consumption per week, exercise habits, K6 score, and baseline PSQI score. Results showed that the average PSQI score decreased by 1.0 in the intervention group but increased by 0.9 in the control group. Additionally, the difference in variation between the two groups was 1.9 (95% confidence interval: 0.6 to 3.4), which was significant. Taken together, these results indicate that the intervention program significantly improved the sleep quality of workers with insomnia.

Analysis of risk of medical errors using structural-equation modelling: a 6-month prospective cohort study.

BACKGROUND: Medical-error analyses have been conducted to determine the root cause of adverse events and near misses. More precise determination of the cause-and-effect relationship likely will require a prospective design path analysis including both direct and indirect effects. METHODS: The authors performed a 6-month prospective cohort study using structural-equation modelling (SEM). Of the 879 nurses approached, 789 (89.8%) were included in the final analysis. Potential predictors provided for analysis included age, years of nursing experience, mean frequency of night shifts per month, nursing-specific job stressors, degree of depression, frequency of feeling unskilled, feeling time pressure, feeling a lack of communication between self and other hospital staff members, frequency of suffering from sleep disturbance and frequency of feeling a decrease in attention. The authors regarded a latent variable composed of frequencies for near misses and adverse events as an outcome. RESULTS AND CONCLUSION: The SEM model constructed in this study suggested that potential root causes (exogenous variables directly or indirectly connected to the outcome which are not affected by other variables) were years of nursing experience, feeling unskilled, job stressors and sleep disturbance, with estimated standardised total (direct and indirect) effects of -0.22, 0.21, 0.008 and 0.005, respectively. A prospective design path analysis using the SEM model for both direct and indirect effects enabled a statistical exploration of root causes and estimation of their impact on the outcome. Our findings suggested such an analysis to be useful in devising countermeasures against medical errors.

Brief morning exposure to bright light improves subjective symptoms and performance in nurses with rapidly rotating shifts.

OBJECTIVE: To investigate whether or not brief bright light (BL) exposure on workday mornings can improve health, performance and safety in nurses with rapidly rotating shifts. METHODS: We conducted a randomized crossover study involving registered nurses at a teaching hospital working a two-shift system including the night shift. Participants were instructed to expose themselves to BL for 10 min on workday mornings. RESULTS: A total of 61 participants were enrolled in the present study. Thirty-one participants received BL exposure in the first month, and the other 30 received it in the second month. Significant improvements were noted in the BL periods compared with the non-BL periods for self-assessed sleepiness at 10:00 on day-shift days evaluated using the Karolinska Sleepiness Scale, self-assessment of night sleep for day-shift days using the Visual Analogue Scale and for fatigue assessed using the Checklist Individual Strength Questionnaire. The estimated mean difference for each scale (95% confidence interval) was -0.55 (-0.91, -0.20), 0.37 (0.04, 0.70) and -2.13 (-3.78, -0.48), respectively. Mean response time evaluated using the psychomotor vigilance task test (PVT) showed significant improvement in the BL periods compared with the non-BL periods. No statistically significant differences were observed for sleepiness at 14:00, depression, number of PVT lapses or frequency of perceived adverse events and near misses. CONCLUSION: Our findings suggest that brief BL exposure on mornings preceding a day shift is effective in improving sleepiness and performance during day-shift work, subjective nighttime sleep on day-shift days, and perceived fatigue for the preceding two weeks in rapidly rotating shift nurses.

Effect of brief sleep hygiene education for workers of an information technology company.

To investigate the effects of sleep hygiene education for workers of an information technology (IT) company, we conducted a controlled clinical trial providing 581 workers one-hour sleep hygiene education. The contents of the sleep hygiene education program were a review of sleep habits, provide sleep hygiene education, and the establishment of sleep habit goals. A self-report questionnaire was used to measure outcomes including the Pittsburgh Sleep Quality Index (PSQI), Karolinska Sleepiness Scale (KSS), Checklist Individual Strength (CIS), Center for Epidemiologic Studies for Depression (CES-D), and mean sleep duration on weekdays before and 4 wk after the intervention. A total of 391 participants were included in the analysis, with 214 participants in the sleep hygiene education group and 177 in the waiting list group. KSS score at 2 P.M. decreased by 0.42 points in the sleep hygiene education group, but increased by 0.08 points in the waiting list group, showing a significant effect size of 0.50 (95%CI, -0.97 to -0.04, p<0.05). PSQI score also improved, but the inter-group difference was not statically significant. The present study provides preliminary evidence that brief sleep hygiene education may improve afternoon sleepiness at work, but not sleep at night for IT workers.

The impact of effort-reward imbalance on quality of life among Japanese working men.

Health-related quality of life (HRQL) is an important measure of health outcome in working and healthy populations. Here, we investigated the impact of effort-reward imbalance (ERI), a representative work-stress model, on HRQL of Japanese working men. The study targeted 1,096 employees from a manufacturing plant in Japan. To assess HRQL and ERI, participants were surveyed using the Japanese version of the Short-Form 8 Health Survey (SF-8) and effort-reward imbalance model. Of the 1,096 employees, 1,057 provided valid responses to the questionnaire. For physical summary scores, the adjusted effort-reward imbalance odds ratios of middle vs. bottom and top vs. bottom tertiles were 0.24 (95% confidence interval, 0.08-0.70) and 0.09 (95% confidence interval, 0.03-0.28), respectively. For mental summary scores, ratios were 0.21 (95% confidence interval, 0.07-0.63) and 0.07 (95% confidence interval, 0.02-0.25), respectively. These findings demonstrate that effort-reward imbalance is independently associated with HRQL among Japanese employees.

Sleep-disordered breathing and hypertension in Japanese steel workers.

Sleep-disordered breathing (SDB) is the major determinants of hypertension. Recent studies indicated sleep duration, in addition to shift work, were also associated with hypertension. But very little attention has been paid to these two factors when looking at the effects of SDB on blood pressure. We conducted the present study to evaluate the relationship between SDB and hypertension adjusting for sleep duration and shift work in a sample of Japanese steel workers. In this cross-sectional study, we measured blood pressure and oxygen desaturations index (ODI) by nocturnal pulse oximetry of 249 male workers aged 20 to 65 yr. SDB was defined by 3%ODI level of 15 or more events per hour. Logistic regression analyses were performed to estimate the associations of SDB with hypertension after adjustment for age, body mass index, alcohol intake, smoking, usual sleep duration, shift work, and occupation. The prevalence of SDB was 18.1%. The adjusted odds ratio of hypertension for high (> or =15) vs. low (<15) category of 3%ODI level was 2.86 (95% confidence interval, 1.23-6.66). The significant association between SDB and hypertension suggests that screening for SDB among steel workers is useful for prevention of hypertension.