A Prospective Cohort Study of Employment Status and Mortality from Circulatory Disorders among Japanese Workers

Examining health risk behaviors of self-employed and employed workers in Japan: a cross-sectional study

OBJECTIVES

Self-employed workers have a higher risk for adverse health outcomes than employed workers. However, the differences in health risk behaviors by employment status are largely unknown. This study examined differences in health risk behaviors between self-employed and employed (permanent/non-permanent) workers by sex and age (20-59 years, 60-79 years).

STUDY DESIGN

This was a cross-sectional study involving community-dwelling adults living in urban cities in Japan.

METHODS

In 2019, we conducted a mail survey in Wako city, Saitama, and Fuchu city, Tokyo. In total, 30,315 adults aged ≥18 years were randomly selected, and 14,185 completed the survey (response rate: 46.8%). The participants for analysis were 8538 workers. Health risk behaviors included physical inactivity (<150 min/wk of moderate-to-vigorous physical activity), prolonged sitting (>480 min/d), high-frequency drinking (≥3 d/wk), tobacco use (current smoker), and overweight (body mass index ≥ 25 kg/m²). We also calculated the total number of health risk behaviors.

RESULTS

Self-employed workers had more health risk behaviors than permanent and non-permanent employees, with this difference more significant among younger males. In younger males, compared with self-employment, permanent employment was associated with less tobacco use, and non-permanent employment was associated with less physical inactivity, prolonged sitting, high-frequency drinking, and overweight. In younger females, non-permanent employment was associated with less prolonged sitting and overweight than self-employment. In older males and females, the prevalence of physical inactivity was lower in non-permanent employed than in self-employed workers.

CONCLUSIONS

Promoting health behaviors among self-employed may be beneficial for reducing health inequalities between self-employed and employed workers.

Employment status and mortality among Korean men over a 13-year period

OBJECTIVES

This study explored the effect of employment status on mortality over a 13-year period in Korean men.

METHODS

Data were used from the Korean Labor and Income Panel Study from 1999 to 2012. This study started with 2,737 subjects and included employed men in good health, aged 30-69 years. Deaths were tracked for 13 years from 2000 to 2012. Employment status classifications were: (1) regular employees, (2) precarious employees, (3) petty bourgeoisie, and (4) employers. Hazard ratios (HRs) were calculated using a Cox proportional hazards model, and were adjusted for age, education, income, and occupation, with regular employees as the reference category. To examine the effect of employment status and include employment history, the risk ratios of mortality were measured using the Poisson regression model, considering the duration of each employment and using 0 years as the reference category.

RESULTS

Over the course of the 13-year study, being a precarious employee (HR, 1.84) or petty bourgeoisie (HR, 1.87) at a particular point in time had a negative effect on mortality when compared with regular employees. Furthermore, working as precarious employees or petty bourgeoisie had no positive effect on mortality. A positive effect was observed, however, on the overall mortality risk for regular employees.

CONCLUSIONS

These results suggest that a healthy social policy is needed for precarious employees and petty bourgeoisie to avoid disadvantages in the workplace and the social safety net.

Self-employment and cardiovascular risk in the US general population

Background

Studies on self-employment and cardiovascular risk are very limited. We examined the relationship between self-employment and cardiovascular risk among the general population in the United States from 1999 to 2016.

Methods

Using the National Health and Nutrition Examination Survey (NHANES), we identified all patients with hypertension (HTN), hyperlipidemia (HLD), diabetes mellitus (DM), stroke, heart failure (HF), and coronary artery disease (CAD) between 1999 and 2016. Type of job was defined based on the participant's response to the survey question as “an employee of a private company, business, or individual for wages, salary, or commission” or “self-employed in own business, professional practice or farm”. Multivariable logistic regression analyses were performed to adjust for confounders.

Results

Of 30,103 patients, 2835 (9.4%) were self-employed in their own business, professional practice, or farm and 27,268 (90.6%) were employed by a private company, business, or government. After adjusting for age, race, sex, BMI, marital status, educational level, health insurance status, smoking status, sleep duration and lipid profiles, self-employed individuals had a higher prevalence of HTN (OR: 1.12; 95% confidence interval [CI] 1.05–1.20), HLD (OR: 1.10; 95% CI 1.07–1.31), stroke (OR: 1.45; 95% CI 1.27–1.67), HF (OR: 1.17; 95% CI 1.03–1.32), and CAD (OR: 1.26; 95% CI 1.13–1.35) (all P v< 0.05).

Conclusions

Self-employment may be associated with greater cardiovascular risk in the US general population. Further prospective studies are urgently needed to establish the optimal preventive strategy to reduce cardiovascular risk in self-employed individuals.

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Self-employment may be associated with cardiovascular risk in the US general

population

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Self-employed individuals may encounter work-related adversity, leading to

cardiovascular risk

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Further prospective studies and clinical trials are urgently needed to establish the optimal preventive strategy for reducing cardiovascular risk associated with self-employment

Association Between Employment Status and Short Sleep Duration Among Middle-Aged Japanese: the Survey on Time Use and Leisure Activities

BACKGROUND

Short sleep duration (SSD) is reported to be highly associated with socio-economic status. There are few studies on the relationship between employment status and SSD in Japan.

METHOD

The authors used the 2006 Survey on Time Use and Leisure Activities conducted by the Ministry of Internal Affairs and Communications Japan, which provides representative samples of Japanese people. The anonymous data of 120,783 people aged 30-59 years were analyzed. Authors defined five categories of employment status: "unemployed," "regularly employed," "non-regularly employed," "self-employed," and "other." Authors also defined a sleep duration shorter than 5 h per night as SSD. Multivariable-adjusted odds ratios (ORs) and 95% confidence intervals (CIs) of SSD using regular employment as the reference group were calculated using the logistic regression model, adjusting for potential confounding factors, i.e., age, marital status, education level, communication device use, and the amount of time spent on various daily activities.

RESULTS

The prevalence of SSD was 2.8% (1639/58,308) in men and 3.2% (1976/62,475) in women. The multivariable-adjusted OR (95% CI) of SSD for the self-employed was 0.78 (0.65-0.92) in men and 1.78 (1.43-2.21) in women after adjustment for potential confounding factors, i.e., age, marital status, education level, and communication device use. Further adjustment for the time spent on daily activities revealed that the OR (95% CI) of SSD for the self-employed was 0.78 (0.65-0.92) in men and 1.89 (1.52-2.36) in women.

CONCLUSION

Self-employed women had a higher prevalence of SSD. By contrast, self-employed men had a lower prevalence of SSD.

Mortality differences between self-employed and paid employees: a 5-year follow-up study of the working population in Sweden

Objectives

Analyse mortality differences between self-employed and paid employees with a focus on industrial sector, educational level and gender using Swedish register data.

Methods

A cohort of the total working population (4 776 135 individuals; 7.2% self-employed; 18–100 years of age at baseline 2003) in Sweden with a 5-year follow-up (2004–2008) for all-cause and cause-specific mortality (57 743 deaths). Self-employed individuals were categorised as sole proprietors or limited liability company (LLC) owners according to their enterprise's legal form. Cox proportional hazards models were applied to compare mortality rates between sole proprietors, LLC owners and paid employees, adjusted for sociodemographic confounders.

Results

Mortality from cardiovascular diseases was 16% lower and from suicide 26% lower among LLC owners than among paid employees, adjusted for confounders. Within the industrial category, all-cause mortality was 13–15% lower among sole proprietors and LLC owners compared with employees in manufacturing and mining (MM) as well as personal and cultural services (PCS), and 11–20% higher in sole proprietors in trade, transport and communication and the welfare industry (W). A significant three-way interaction indicated 17–23% lower all-cause mortality among male LLC owners in MM and female sole proprietors in PCS, and 50% higher mortality in female sole proprietors in W than in employees in the same industries.

Conclusions

Mortality differences between self-employed individuals and paid employees vary by the legal form of self-employment, across industries, and by gender. Differences in work environment exposures and working conditions, varying market competition across industries and gender segregation in the labour market are potential mechanisms underlying these findings.

Serum Albumin Levels and Economic Status in Japanese Older Adults

BACKGROUND

Low serum albumin levels are associated with aging and medical conditions such as cancer, liver dysfunction, inflammation, and malnutrition and might be an independent predictor of long-term mortality in healthy older populations. We tested the hypothesis that economic status is associated with serum albumin levels and explained by nutritional and health status in Japanese older adults.

DESIGN

We performed a cross-sectional analysis using data from the Japan Gerontological Evaluation study (JAGES). The study participants were 6528 functionally independent residents (3189 men and 3339 women) aged ≥65 years living in four municipalities in Aichi prefecture. We used household income as an indicator of economic status. Multiple linear regression was used to compare serum albumin levels in relation to household income, which was classified as low, middle, and high. Additionally, mediation by nutritional and health-related factors was analyzed in multivariable models.

RESULTS

With the middle-income group as reference, participants with low incomes had a significantly lower serum albumin level, even after adjustment for sex, age, residential area, education, marital status, and household structure. The estimated mean difference was -0.17 g/L (95% confidence interval, -0.33 to -0.01 g/L). The relation between serum albumin level and low income became statistically insignificant when "body mass index", "consumption of meat or fish", "self-rated health", "presence of medical conditions", "hyperlipidemia", or "respiratory disease "was included in the model.

CONCLUSION

Serum albumin levels were lower in Japanese older adults with low economic status. The decrease in albumin levels appears to be mediated by nutrition and health-related factors with low household incomes. Future studies are needed to reveal the existence of other pathways.

Association of household income and education with eating behaviors in Japanese adults: a cross-sectional study

BACKGROUND

Socioeconomic inequalities as social determinants of health are important issues in public health and health promotion. However, the association between socioeconomic status and eating behaviors has been investigated poorly in Japanese adults. To fill this gap, the present study examines the association of eating behaviors with household income and education.

METHODS

The sample comprised 3,137 Japanese adults (1,580 men and 1,557 women) aged 30 to 59 years who responded to an Internet-based cross-sectional survey in 2014. Data on the following eating behaviors were collected via self-report: "taking care of one's diet for health," "eating vegetables," "frequency of eating breakfast," "frequency of family breakfasts," "frequency of family dinners," "using the information on nutrition labels," and "conversations with family or friends during meals." Self-reported data on socioeconomic status (household income and education) and demographic variables (gender, age, district of residence, marital status, residence status, and employment status) were also collected. The associations between eating behaviors and household income or education were tested using binomial logistic regression analysis with eating behaviors as dependent variables and household income and education as independent variables. A trend P -value was calculated for three categories of household income (less than 3,000,000 JPY, 3,000,000-7,000,000 JPY, and over 7,000,000 JPY) and education (junior high/high school, 2-year college, and 4-year college/graduate school).

RESULTS

Higher household income and education were significantly associated with higher rates of eating vegetables, using the information on nutrition labels, and conversation with family or friends during meals in Japanese men and women. Higher household incomes were significantly associated with lower rates of frequency of family breakfasts in Japanese men and lower rates of frequency of family dinners in Japanese men and women.

CONCLUSIONS

Higher socioeconomic status as indicated by household income or education was associated with eating more vegetables and conversation with family or friends during meals in Japanese men and women. Socioeconomic status should be considered in health promotion and diet improvement.

Self-employment in joinery: an occupational risk facor?

OBJECTIVES

Only a few studies have analyzed the health of self-employed workers. This cross-sectional study is the first to compare health status among craftsmen joiners and paid joiners.

MATERIAL AND METHODS

Clinical and paraclinical data for self-employed craftsmen and employees were collected by occupational health doctors according to a standardized protocol and compared. Health data and professional status relationships were analyzed by logistic regression.

RESULTS

A total of 171 craftsmen and 196 paid workers were included. Craftsmen had more dermatologic pathologies (odds ratio (OR) = 2.67, p < 0.05), ear/nose/throat symptoms (OR = 3.38, p < 0.001), pulmonary symptoms (OR = 2.46, p < 0.05), musculoskeletal symptoms (OR = 3.09, p < 0.001), and abnormal audiogram (OR = 3.50, p < 0.001). The FEV1 was significantly lower among craftsmen (p < 0.01), independently of tobacco smoke exposure.

CONCLUSIONS

This survey high-lights a high morbidity rate among self-employed craftsmen, suggesting that among woodworkers, professional status can be a risk factor for health. The preventive medical system for craftsmen has to be rethought to guarantee better safety for this population.

Health inequalities in Japan: the role of material, psychosocial, social relational and behavioural factors

The extent that risk factors, identified in Western countries, account for health inequalities in Japan remains unclear. We analysed a nationally representative sample (Comprehensive Survey of Living Conditions surveyed in 2001 (n = 40,243)). The cross-sectional association between self-rated fair or poor health and household income and a theory-based occupational social class was summarised using the relative index of inequality [RII]. The percentage attenuation in RII accounted for by candidate contributory factors - material, psychosocial, social relational and behavioural - was computed. The results showed that the RII for household income based on self-rated fair or poor health was reduced after including the four candidate contributory factors in the model by 20% (95% CI 2.1, 43.6) and 44% (95% CI 18.2, 92.5) in men and women, respectively. The RII for the Japanese Socioeconomic Classification [J-SEC] was reduced, not significantly, by 22% (95% CI -6.3, 100.0) in men in the corresponding model, while J-SEC was not associated with self-rated health in women. Material factors produced the most consistent and strong attenuation in RII for both socioeconomic indicators, while the contributions attributable to behaviour alone were modest. Social relational factors consistently attenuated the RII for both socioeconomic indicators in men whereas they did not make an independent contribution in women. The influence of perceived stress was inconsistent and depended on the socioeconomic indicator used. In summary, social inequalities in self-rated fair or poor health were reduced to a degree by the factors included. The results indicate that the levelling of health across the socioeconomic hierarchy needs to consider a wide range of factors, including material and psychosocial factors, in addition to the behavioural factors upon which the current public health policies in Japan focus. The analyses in this study need to be replicated using a longitudinal study design to confirm the roles of different factors in health inequalities.

Occupational class and incidence rates of cardiovascular events in middle aged men in Japan

We investigated whether occupational class affects the incidence of cardiovascular events in Japanese factory workers. We prospectively evaluated 1,794 male workers aged 40-59, including 632 non-manual and 1,162 manual workers, employed in a metal products factory in Japan. The hazard ratios of stroke, myocardial infarction (MI) and cardiovascular events (combined stroke, MI and sudden cardiac death) for manual workers were compared with non-manual workers as estimated by the Cox proportional hazards regression model. Among the 1,794 workers, there were 60 cardiovascular events (32 cases of stroke, 23 cases of MI and 5 cases of sudden cardiac death) with an incidence rate of 3.14 per 1,000 person-years for cardiovascular events; 1.68 for stroke and 1.20 for MI. Blood pressure and HbA1c significantly increased the risk of stroke. Body mass index and total cholesterol significantly increased the risk of MI. However, occupational class was determined not to be a risk factor for cardiovascular events. The hazard ratios of stroke, MI and cardiovascular events for manual workers compared with non-manual workers were 0.97 (95%CI, 0.45-2.08), 0.73 (95%CI, 0.30-1.79) and 0.92 (95%CI, 0.53-1.61), respectively. Our study did not reveal significant occupational class inequalities in the rate of cardiovascular events. These findings are not in accordance with studies from other industrialized countries.

Employment status and use of respiratory protection among metalworkers, solderers and welders

OBJECTIVES

Reported associations of self-employment with occupational injury and cerebrovascular disease suggest that worker safety and health precautions may vary by occupational status. The authors assessed the extent to which use of respiratory protection and ventilation equipment is associated with self-employed versus employee status among adults in an international study.

METHODS

The European Community Respiratory Health Survey II (ECRHS II) is a follow-up study conducted in a population-based random sample of adult ECRHS I participants. Men and women enrolled in the ECRHS II completed interviewer-administered questionnaires to provide information about their occupational status and job history during the 9-year ECRHS follow-up period. Respondents in selected occupational groups completed supplemental questionnaires about their jobs and use of respiratory protection and ventilation equipment on-the-job. The authors assessed self-reported use of respiratory and ventilation equipment among 72 self-employed and 371 employed adults in metalworking, soldering and welding occupations.

RESULTS

Local exhaust ventilation (fixed extraction: OR 0.37, 95% CI 0.17 to 0.80; mobile extraction: OR 0.23, 95% CI 0.09 to 0.60; on-tool extraction: OR 0.39, 95% CI 0.18 to 0.88) was reported less frequently among self-employed respondents than among employed respondents. The magnitude of the negative association between self-employment status and any of the three types of local exhaust ventilation was not attenuated by adjustment for duration of work per day or week or asthma and/or wheezing symptoms. Respiratory protection was not associated with employment status in these data.

CONCLUSIONS

More limited use of local exhaust ventilation among self-employed workers compared to employees suggests the need to promote occupational safety among self-employed workers.