Effect of Long Working Hours on Self-reported Hypertension among Middle-aged and Older Wage Workers

Systematic review and meta-analysis of the association between long working hours and hypertension risk

BACKGROUND

Hypertension, a major public health problem worldwide, has been linked to lifestyle factors and work conditions, with conflicting evidence on the association between long work hours and risk of hypertension.

METHODS

We conducted a systematic review and meta-analysis of observational studies to investigate the relationship between working hours and hypertension or blood pressure, assessed the risk of bias and performed subgroup analyses. The protocol was registered with the International Prospective Register of Systematic Reviews.

RESULTS

The pooled OR for the association between long working hours and risk of hypertension was 1.09 (95% CI: 0.88 to 1.35) in the 15 studies that used hypertension as the outcome. In the three studies that used blood pressure as the outcome, diastolic blood pressure was higher among those with long working hours compared with those with non-long working hours (1.24 mm Hg, 95% CI: 0.19 to 2.29). In subgroup analysis, the pooled OR for the association between long working hours and risk of hypertension was 1.28 (95% CI: 1.14 to 1.44) and 1.00 (95% CI: 0.64 to 1.56) in women and men, respectively.

CONCLUSIONS

Although this study could not clearly confirm the relationship between long working hours and hypertension, the subgroup analysis suggests that long working hours may be associated with hypertension, particularly among women. More reliable research is needed to establish causality.

PROSPERO REGISTRATION NUMBER

CRD42023406961.

Unveiling the Global Surge: Unraveling the Factors Fueling the Spread of Karoshi Syndrome

Karoshi syndrome, also known as "death by overwork", has been a topic of study and concern in Japan since the 1980s. World Health Organization (WHO) and International Labour Organization (ILO) joint unveiled that in 2021, approximately 750.000 deaths due to Karoshi syndrome globally. The joint defined long working as having > 55 h work/week. Karoshi nowadays is no longer limited to Japan and has become a global issue. Karoshi is primarily attributed to factors such as long working hours, job-related stress, and poor work-life balance. This perspective was sought to provide a short overview of Karoshi syndrome, the underlying mechanisms and the state-of-art preventive measures.

Risk prediction model of self-reported hypertension for telemedicine based on the sociodemographic, occupational and health-related characteristics of seafarers: a cross-sectional epidemiological study

OBJECTIVES

High blood pressure is a common health concern among seafarers. However, due to the remote nature of their work, it can be difficult for them to access regular monitoring of their blood pressure. Therefore, the development of a risk prediction model for hypertension in seafarers is important for early detection and prevention. This study developed a risk prediction model of self-reported hypertension for telemedicine.

DESIGN

A cross-sectional epidemiological study was employed.

SETTING

This study was conducted among seafarers aboard ships. Data on sociodemographic, occupational and health-related characteristics were collected using anonymous, standardised questionnaires.

PARTICIPANTS

This study involved 8125 seafarers aged 18-70 aboard 400 vessels between November 2020 and December 2020. 4318 study subjects were included in the analysis. Seafarers over 18 years of age, active (on duty) during the study and willing to give informed consent were the inclusion criteria.

OUTCOME MEASURES

We calculated the adjusted OR (AOR) with 95% CIs using multiple logistic regression models to estimate the associations between sociodemographic, occupational and health-related characteristics and self-reported hypertension. We also developed a risk prediction model for self-reported hypertension for telemedicine based on seafarers' characteristics.

RESULTS

Among the 4318 participants, 55.3% and 44.7% were non-officers and officers, respectively. 20.8% (900) of the participants reported having hypertension. Multivariable analysis showed that age (AOR: 1.08, 95% CI 1.07 to 1.10), working long hours per week (AOR: 1.02, 95% CI 1.01 to 1.03), work experience at sea (10+ years) (AOR: 1.79, 95% CI 1.33 to 2.42), being a non-officer (AOR: 1.75, 95% CI 1.44 to 2.13), snoring (AOR: 3.58, 95% CI 2.96 to 4.34) and other health-related variables were independent predictors of self-reported hypertension, which were included in the final risk prediction model. The sensitivity, specificity and accuracy of the predictive model were 56.4%, 94.4% and 86.5%, respectively.

CONCLUSION

A risk prediction model developed in the present study is accurate in predicting self-reported hypertension in seafarers' onboard ships.

Occupational risk factors for hypertension

The identification and characterization of the modifiable risk factors of hypertension is of great value for public health and clinical medicine to achieve primary prevention. A large amount of literature on the effects of occupational factors on blood pressure and hypertension has been published. In this review, I summarize current evidence regarding the role of occupational factors in hypertension. The results of this review suggest that there is sufficient evidence to support the association between increased risk of hypertension and job stress, shift work, occupational lead exposure, and noise exposure. The association of hypertension with physical inactivity, sedentary behavior, and occupational exposure to mercury, arsenic, cadmium, or carbon disulfide remains inconclusive, although several studies have reported this finding. This review will serve as a step toward future research and provide baseline information for developing strategic interventions to prevent hypertension in the working population.

Long working hours associated with elevated ambulatory blood pressure among female and male white-collar workers over a 2.5-year follow-up

Population-based strategies targeting modifiable risk factors are needed to improve the prevention of hypertension. Long working hours have been linked to high blood pressure (BP), but more longitudinal research is required. The objective of this study was to examine the effect of long working hours (≥41 h/week) on ambulatory BP mean over a 2.5-year follow-up. The effect modification of family responsibilities was also investigated. A repeated longitudinal design was used. Data collection was performed at three-time points over a 2.5-year follow-up among over 2000 white-collar workers. Working hours were self-reported assessed by questionnaire. BP was measured using Spacelabs 90207. The outcomes were systolic and diastolic BP mean. Cross-lagged GEE linear regressions were used to examine whether working hours were associated with BP means at the next measurement time. Women working long hours had a higher diastolic BP mean at follow-up compared to women working regular hours (+1.8 mm Hg (95% CI: 0.5-3.1)). In men, those working long hours had both higher systolic and diastolic BP means increases (systolic: +2.5 mm Hg (95% CI: 0.5-4.4)) and diastolic: +2.3 mm Hg (95% CI: 1.0-3.7)). This association was greater among workers having high family responsibilities. This longitudinal study showed that women and men working long hours had higher BP means when compared those working 35-40 h per week. These findings suggest that strategies that promote work weeks not exceeding 40 h might contribute to the primary prevention of hypertension, especially for workers with high family responsibilities.

Working hours are closely associated with depressive mood and suicidal ideation in Korean adults: a nationwide cross-sectional study

Long working hours have been presumed to negatively influence health. However, evidence is lacking regarding any associations of working hours with depressive mood or suicidal ideation. We investigated the relationships of working hours with depressive mood and suicidal ideation in a representative sample of the Korean general population. We analyzed data collected by the Korea National Health and Nutrition Examination Surveys VI and VII (2013–2018). Depressive mood and suicidal ideation were identified through self-reporting. We divided participants into four groups according to weekly working hours: 30–40, 41–50, 51–60, and > 60 h/week. Sampling weights were applied to obtain estimates for the general Korean population. We analyzed 14,625 participants, of whom 5383 (36.8%), 4656 (31.8%), 2553 (17.5%), and 2033 (13.9%) worked 30–40, 41–50, 51–60, and > 60 h/week, respectively. In these groups, 3.6%, 4.4%, 5.2%, and 6.3% of the participants reported depressive mood, while 1.8%, 1.9%, 2.2%, and 3.6% reported suicidal ideation. In multiple regression analyses, compared with the 30–40 h/week group, the adjusted odds ratios of the 41–50, 51–60, and > 60 h/week groups for depressive mood were 1.35 (1.08–1.69), 1.5 (1.14–1.97), and 1.6 (1.19–2.14). A similar trend was evident for suicidal ideation (odds ratios 1.16 [0.82–1.63], 1.48 [0.99–2.21], and 2.29 [1.53–3.42]). Long working hours are significantly associated with depressive mood and suicidal ideation.

The combined effect of long working hours and individual risk factors on cardiovascular disease: An interaction analysis

Objectives

We examined whether the effect of long working hours on the risk of developing cardiovascular disease (CVD) differs depending on individual risk factors.

Methods

Seven‐year follow‐up data were extracted from the 2009 to 2016 waves of the Korea Health Panel Survey. Physician's diagnosis or medication for hypertension, diabetes, dyslipidemia, and obesity were included as chronic disease status. Smoking, drinking alcohol, and exercise levels were considered as lifestyle behavior. Hazard ratios were calculated using the Cox regression models to evaluate the risk of CVD related to chronic diseases and unhealthy behavior, based on working hour groups, after adjusting for other covariates. The interactive effects of long working hours with or without chronic diseases and unhealthy behavior on CVD were assessed using the relative excess risk due to interaction and attributable proportion measures.

Results

There was a statistically significant interaction between long working hours and chronic diseases within the population, especially among male participants (P‐value for interaction <.01 and .03, respectively). There were no significant interactions between unhealthy behavior and long working hours.

Conclusions

Long working hours and chronic disease have a synergistic negative effect on the risk of CVD.

Occupational Physical Activity and New-Onset Hypertension: A Nationwide Cohort Study in China

[Figure: see text].

Dose-response relationship between working hours and hypertension: A 22-year follow-up study

Hypertension causes a substantial burden to society. Some studies found that hypertension was associated with the working type and working hours. The purpose of the current study is to assess the dose-response relationship between working hours and hypertension.Data of 12,080 adults aged 18 to 65 years who attended the China Health and Nutrition Survey (CHNS) between 1989 and 2011 were analyzed. Hypertension was determined based on systolic and/or diastolic blood pressure measures, or having doctor-diagnosed hypertension. Multivariable Cox regression and restricted cubic spline to assess the dose-response relationship between working hours and hypertension.A total of 12,080 participants including 5852 females and 6228 males. By the last follow-up (2011), a total of 830 participants were hypertensive, with an incidence of 6.9%. After adjusting socio-demographic, lifestyle factors, as well as occupation type, compared with those who worked 35 to 49 hours per week, participants who worked no more than 34 hours per week (HR: 1.21, 95%CI: 1.03-1.41) and at least 56 hours per week (HR: 1.38, 95%CI: 1.19-1.59) had a higher risk of hypertension. The significant association between long working hours (at least 56 hours per week) and hypertension was observed among females (HR: 1.38, 95%CI: 1.16-1.64) and males (HR: 1.36, 95%CI: 1.04-1.78). Among manual workers, the relationship between long working hours and hypertension was observed (HR: 1.49, 95%CI: 1.10-2.02). The relationship between long working hours (HR: 1.21, 95%CI: 1.01-1.44) and short working hours (HR: 1.37, 95%CI: 1.16-1.61) and hypertension was observed among nonmanual workers. The hazard ratio of hypertension and working time displayed U-shape non-linear relationship (Ptrend < .001, non-linear P < .001). The non-linear response-dose relationship was found in manual worker, nonmanual worker, and male (Ptrend < .001, non-linear P < .001).The association between working time and hypertension showed U-shape relationship. Specifically, overtime work was an important occupational risk factors for adults, and short work time was related to hazard ratio of hypertension in nonmanual workers.

Cross-sectional association between long working hours and liver function: the Kangbuk Samsung Health Study

OBJECTIVES

Although the effects of long working hours on liver function remain unclear, in South Korea, there is a social perception that long working hours are associated with poor liver function. Thus, long working hours have recently become a major issue. This study aimed to determine the association between long working hours and liver function, as indicated by the alanine transaminase (ALT) levels.

DESIGN

Cross-sectional study.

SETTING

Large university hospitals in Seoul and Suwon, South Korea.

PARTICIPANTS

Workers in formal employment who underwent a comprehensive health examination at the Kangbuk Samsung Hospital Total Healthcare Centre clinics in Seoul and Suwon, South Korea, between January 2011 and December 2018. Of the 386 488 participants, 212 421 met the inclusion criteria and were included in the analysis.

PRIMARY OUTCOME MEASURE

ALT elevation.

RESULTS

The participants were predominantly well-educated (86.1%), male (69.3%) and in their 30s (49.6%). In total, 13.4% of the participants presented ALT elevation (>40 IU/L). There was no significant association between working hours and ALT elevation in the general population and in the hepatitis B surface antigen (HBsAg)-negative group. Conversely, in the HBsAg-positive group, working >60 hours per week compared with 35-40 hours per week was significantly associated with ALT elevation. The association was more pronounced in those with ALT levels >80 IU/L (OR 1.94, 95% CI 1.24 to 3.01) than in those with ALT levels >40 IU/L (OR: 1.45, 95% CI 1.20 to 1.75). The p values for trend were <0.05.

CONCLUSIONS

Long working hours were associated with ALT elevation only in hepatitis B virus carriers and not in the general population. Provided that there is adherence to the legal working hours, there is no need to further restrict working hours for liver health, irrespective of HBsAg status.

The negative impact of long working hours on mental health in young Korean workers

Long working hours are known to have a negative effect on health. However, there is no clear evidence for a direct link between mental health and long working hours in the young adult populations. Therefore, we aimed to determine whether long working hours are associated with mental health in young adult workers. Data were collected from a 2012 follow-up survey of the Youth Panel 2007. A total of 3,332 young adult employees (aged 20 to 35) were enrolled in the study. We analyzed stress, depression, and suicidal thoughts by multivariate logistic regression analysis based on working hours (41 to 50, 51 to 60 and over 60 hours, compared to 31 to 40 hours per week), which was adjusted for sex, age, marriage status, region, and educational level. From the 3,332 young adult employees, about 60% of the workers worked more than 40 hours and 17% of the workers worked more than 50 hours per week. In a Chi-square test, stress level, depression, and suicidal thoughts increased with increasing working hours (p-value <0.001, 0.007, and 0.018, respectively). The multivariate logistic regression model showed that, compared to the 31 to 40 hours per week group, the adjusted odds ratios of the 41 to 50, 51 to 60, and over 60 hours per week groups for stress were 1.46(1.23–1.74), 2.25(1.79–2.83) and 2.55(1.72–3.77), respectively. A similar trend was shown in depression [odds ratios: 2.08(1.23–3.53), 2.79(1.44–5.39) and 4.09(1.59–10.55), respectively] and suicidal ideation [odds ratios: 1.98(0.95–4.10), 3.48(1.48–8.19) and 5.30(1.61–17.42), respectively]. We concluded that long working hours were associated with stress, depression, and suicidal ideation in young employees, aged 20 to 35.

Long work hours and decreased glomerular filtration rate in the Korean working population

OBJECTIVES

We studied the association between long working hours and decreased kidney function, which was determined using estimated glomerular filtration rate (eGFR), among the working population in South Korea.

METHODS

We analysed nationally representative cross-sectional data for 20 851 Korean workers ≥20 years of age. A negative binomial regression model was used to test differences in the prevalence of chronic kidney disease (eGFR <60 mL/min/1.73 m²) among workers divided into groups according to weekly working hours (<30, 30-40, 41-51 and ≥52 hours/week). Multivariate linear regression analysis was performed to investigate the association between weekly working hours and eGFR, with adjustments made for age, sex/gender, income, education, shift work, occupation, smoking, alcohol use, hypertension, diabetes mellitus, body mass index, systolic blood pressure, fasting blood glucose and total serum cholesterol.

RESULTS

A 1-hour increase in weekly working hours was associated with 0.057 mL/min/1.73 m² (95% CI 0.005 to 0.109) decrease in eGFR among participants who worked ≥52 hours/week. Among participants without hypertension or diabetes, a 1-hour increase in weekly working hours was significantly associated with 0.248 and 0.209 mL/min/1.73 m² decrease in eGFR among participants who worked 30-40 hours/week and 41-51 hours/week, respectively.

CONCLUSION

Long working hours are associated with decreased kidney function. We expect that our findings could call for more research regarding this association and provide policy-oriented perspectives.

Long Working Hours and the Prevalence of Masked and Sustained Hypertension

Previous studies on the effect of long working hours on blood pressure have shown inconsistent results. Mixed findings could be attributable to limitations related to blood pressure measurement and the lack of consideration of masked hypertension. The objective was to determine whether individuals who work long hours have a higher prevalence of masked and sustained hypertension. Data were collected at 3-time points over 5 years from 3547 white-collar workers. Long working hours were self-reported, and blood pressure was measured using Spacelabs 90207. Workplace clinic blood pressure was defined as the mean of the first 3readings taken at rest at the workplace. Ambulatory blood pressure was defined as the mean of the next readings recorded every 15 minutes during daytime working hours. Masked hypertension was defined as clinic blood pressure < 140/90 mm Hg and ambulatory blood pressure ≥135/85 mm Hg. Sustained hypertension was defined as clinic blood pressure ≥140/90 mm Hg and ambulatory blood pressure ≥135/85 mm Hg or being treated hypertension. Long working hours were associated with the prevalence of masked hypertension (prevalence ratio 49+ =1.70 [95% CI, 1.09–2.64]), after adjustment for sociodemographics, lifestyle-related risk factors, diabetes mellitus, family history of cardiovascular disease, and job strain. The association with sustained hypertension was of a comparable magnitude (prevalence ratio 49+ =1.66 [95% CI, 1.15–2.50]). Results suggest that long working hours are an independent risk factor for masked and sustained hypertension. Workplace strategies targeting long working hours could be effective in reducing the clinical and public health burden of hypertension.

The Association Between Long Working Hours and High-Sensitivity C-Reactive Protein in Older Aged Individuals: The Korea National Health and Nutrition Examination Survey (KNHANES) 2015

OBJECTIVE

The objective of this study was to show the association of high-sensitivity C-reactive protein (hs-CRP) level with working hours in different age groups.

METHODS

We used data from Korean National Health and Nutrition Survey. The odds ratios (ORs) and 95% confidence intervals (CIs) of variables for elevated hs-CRP (>3.0 mg/L) were generated with logistic regression models. Significant variables were verified with an adjusted multivariate logistic model after stratification of age groups.

RESULTS

Working for more than 55 hours per week was associated with elevated hs-CRP level in the old-ages group (≥ 60 years old: OR 2.18, 95% CI 1.07 to 4.45). Working for 40 to 55 hours per week was associated with decreased hs-CRP in the young-ages group (OR 0.58, 95% CI 0.37 to 0.93).

CONCLUSION

Working hours appear to influence the levels of hs-CRP in individuals aged older than 60 years.

Karoshi May Be a Consequence of Overwork-Related Malignant Arrhythmia

Background

Karoshi, which is sudden death associated with overwork, has become a serious problem in China. Many studies have examined the relationship between cardiovascular risks and karoshi, but there is little evidence that explains the exact mechanism by which overwork induces sudden death. In these cases, there are few obvious positive findings from forensic autopsies except for histories of overwork prior to death. Therefore, we assume that abnormalities, such as cardiac arrhythmia, rather than organic changes are the cause of karoshi.

Material/Methods

In the present study, the forced swim test (FST) was used to establish models of overwork. The myocardial tissues of SD rats taking FST (1 h per day, for 30 consecutive days) were collected. The arrhythmia-related molecule CX43 as well as its upstream regulation molecule Cav-1 and cSrc were tested by Western blot (WB) and immunohistochemistry (IHC). HE staining and Masson‘s staining were performed in the myocardium tissue section.

Results

We observed downregulation of caveolin-1 (Cav1) followed by cSrc activation, resulting in the decrease of connexin43 (Cx43) levels in overwork models. Myocardial interstitial fibrosis, which is associated with electrophysiological aberrances that result in arrhythmia, was also found in the overwork models.

Conclusions

These data provide a mechanistic explanation for the speculated link between karoshi and cardiac arrhythmias.

Long working hours, anthropometry, lung function, blood pressure and blood-based biomarkers: cross-sectional findings from the CONSTANCES study

Background

Although long working hours have been shown to be associated with the onset of cardiometabolic diseases, the clinical risk factor profile associated with long working hours remains unclear. We compared the clinical risk profile between people who worked long hours and those who reported being never exposed to long hours.

Methods

A cross-sectional study in 22 health screening centres in France was based on a random population-based sample of 75 709 participants aged 18–69 at study inception in 2012–2016 (the CONSTANCES study). The data included survey responses on working hours (never, former or current exposure to long working hours), covariates and standardised biomedical examinations including anthropometry, lung function, blood pressure and standard blood-based biomarkers.

Results

Among men, long working hours were associated with higher anthropometric markers (Body Mass Index, waist circumference and waist:hip ratio), adverse lipid levels, higher glucose, creatinine, white blood cells and higher alanine transaminase (adjusted mean differences in the standardised scale between the exposed and unexposed 0.02–0.12). The largest differences were found for Body Mass Index and waist circumference. A dose–response pattern with increasing years of working long hours was found for anthropometric markers, total cholesterol, glucose and gamma-glutamyltransferase. Among women, long working hours were associated with Body Mass Index and white blood cells.

Conclusion

In this study, men who worked long hours had slightly worse cardiometabolic and inflammatory profile than those who did not work long hours, especially with regard to anthropometric markers. In women, the corresponding associations were weak or absent.

Long Working Hours and Risk of Cardiovascular Disease

Purpose of Review

To summarize the evidence on the relationship between long working hours and cardiovascular disease, such as coronary heart disease and stroke.

Recent Findings

Large-scale meta-analyses with published and individual participant observational data on more than 740,000 men and women free of cardiovascular disease report a link between long working hours (≥ 55 h a week) and the onset of cardiovascular events. Our meta-analytic update of summary evidence suggests a 1.12-fold (95% CI 1.03–1.21) increased risk associated with coronary heart disease and a 1.21-fold (95% CI 1.01–1.45) increased risk of stroke, although the evidence is somewhat inconsistent and the possibility of residual confounding and bias cannot be ruled out. Few studies have examined the mechanisms which may be stress-related, behavioral, or biological. The recent pooled analyses suggest that increased cardiac electric instability and hypercoagulability might play a role.

Summary

The evidence that long working hours are a risk factor for cardiovascular disease is accumulating and suggests a small risk. Studies on the effects of long working hours in high-risk populations and those with pre-existing cardiovascular disease, mechanistic research, and intervention studies are needed to advance this research field.

Long weekly working hours and ischaemic heart disease: a follow-up study among 145 861 randomly selected workers in Denmark

OBJECTIVES

The aim of the present study was to test if incidences of ischaemic heart disease (IHD) and usage of antihypertensive drugs are independent of weekly working hours (WWH) among full-time employees in Denmark.

DESIGN AND PARTICIPANTS

Data on WWH from participants of the Danish labour force surveys, 1999-2013, were linked on an individual level to national registers with data on socioeconomic status (SES), industry, emigrations, redeemed prescriptions, hospital contacts and deaths. Participants were followed until the end of 2014 (on average 7.7 years). Poisson regression was used to model incidence rates as a function of WWH. The analyses were controlled for calendar time, time passed since start of follow-up, employment in the healthcare industry, age, sex, SES and night work.

RESULTS

In total, we found 3635 cases of IHD and 20 648 cases of antihypertensive drug usage. The rate ratio of IHD was 0.95 (95% CI 0.85 to 1.06) for 41-48 compared with 32-40 WWH and 1.07 (0.94 to 1.21) for >48 compared with 32-40 WWH. The corresponding rate ratios for antihypertensive drug usage were 0.99 (0.95 to 1.04) and 1.02 (0.97 to 1.08). No statistically significant interactions between WWH and sex, SES and night work, respectively, were found.

CONCLUSION

In this Danish sample, we did not find any statistically significant association between WWH and IHD or antihypertensive drug usage.

The association between long working hours and hearing impairment in noise unexposed workers: data from the 5th Korea National Health and Nutrition Examination Survey (KNHANES 2010-2012)

BACKGROUND

This study is aimed at finding out the relationship between long working hours, one of major job stress elements, and hearing impairment in unexposed workers to occupational and environmental noise.

METHODS

This study was performed on 1628 regular, full-time wage workers between the age of 25-64 who indicated in the survey of having no experience of exposure to noise, normal otoscopic findings, and not suffering from diabetes based on the data from the fifth Korea National Health and Nutrition Examination Survey (KNHANES 2010-2012). The average working hours per week was categorized into 40 h and lower group, more than 40 to 48 h group, more than 48 to 60 h group, and more than 60 h group. The groups were defined as suffering from low or high frequencies hearing impairment if the average hearing threshold for 0.5, 1, 2 kHz or 3, 4, 6 kHz in both ears exceeds 25 dB based on the pure tone audiometry. The association between average weekly working hours and hearing impairment was analyzed using logistic regression after gender stratification.

RESULTS

The prevalences of low and high frequencies hearing impairment in male workers were 4.3 and 28.6 %, respectively, which were much higher than female's prevalence of 2.7 and 11.1 %. For male workers, no significant association was found between average weekly working hours and low and high frequencies hearing impairment. For female workers, odds ratios (OR) of low and high frequencies hearing impairment were 4.22 (95 % confidence interval (CI) 1.09-16.27) and 4.49 (95 % CI 1.73-11.67), respectively, after controlling for several related factors, such as, age, Body Mass Index (BMI), socio-economic status, health-related behavioral, and occupational characteristics variables, in the final model in the group working more than 60 h compared to the group working 40 h and lower. In addition, a dose-response relationship was observed that ORs of low and high frequencies hearing impairment were increased according to increasing average weekly working hours.

CONCLUSIONS

The association between long working hours and hearing impairment in both low and high frequencies was significant in Korean female workers with a dose-response relationship. Therefore, the law to change the culture of long working hours should be enacted in order to protect the workers' health and improve the quality of life in Korean workers.

Dose-Response Relation Between Work Hours and Cardiovascular Disease Risk: Findings From the Panel Study of Income Dynamics

OBJECTIVES

The aim of this study was to examine the presence of a dose-response relationship between work hours and incident cardiovascular disease (CVD) in a representative sample of U.S. workers.

METHODS

A retrospective cohort study of 1926 individuals from the Panel Study of Income Dynamics (1986 to 2011) employed for at least 10 years. Restricted cubic spline regression was used to estimate the dose-response relationship of work hours with CVD.

RESULTS

A dose-response relationship was observed in which an average workweek of 46 hours or more for at least 10 years was associated with an increased risk of CVD. Compared with working 45 hours per week, working an additional 10 hours per week or more for at least 10 years increased CVD risk by at least 16%.

CONCLUSION

Working more than 45 work hours per week for at least 10 years may be an independent risk factor for CVD.

Occupational Disparities in the Association between Self-Reported Salt-Eating Habit and Hypertension in Older Adults in Xiamen, China

Blood pressure responses to sodium intake are heterogeneous among populations. Few studies have assessed occupational disparities in the association between sodium intake and hypertension in older people. We used cross-sectional data from 14,292 participants aged 60 years or older in Xiamen, China, in 2013. Self-reported salt-eating habit was examined with three levels: low, medium, and high. The main lifetime occupation was classified into indoor laborer and outdoor laborer. Multivariable logistic regression was used to examine associations of hypertension with self-reported salt-eating habit, main lifetime occupation, and their interactions by adjusting for some covariates, with further stratification by sex. Overall, 13,738 participants had complete data, of whom 30.22% had hypertension. The prevalence of hypertension was 31.57%, 28.63%, and 31.97% in participants who reported to have low, medium, and high salt-eating habit, respectively. Outdoor laborers presented significantly lower prevalence of hypertension than indoor laborers (26.04% vs. 34.26%, p < 0.001). Indoor laborers with high salt-eating habit had the greatest odds of hypertension (OR = 1.32, 95% CI [1.09–1.59]). An increased trend of odds in eating habit as salt-heavier was presented in indoor laborers (p-trend = 0.048), especially for women (p-trend = 0.001). No clear trend presented in men. Conclusively, sex-specific occupational disparities exist in the association between self-reported salt-eating habit and hypertension in older individuals. Overlooking the potential moderating role of sex and occupation might affect the relationship between sodium intake and hypertension.