A meta-analysis of observational studies including dose-response relationship between long working hours and risk of obesity

The associations of long working hours and unhealthy diet with cardiometabolic outcomes and mortality in US workers

OBJECTIVES

To examine independent and joint associations of long working hours (LWH) and EAT-Lancet diet with cardiometabolic outcomes and mortality in US workers.

METHODS

This prospective cohort included US workers from the National Health and Nutrition Examination Survey, with cross-sectional baseline data from 1999 to March 2020. A subsample of participants from 1999 to 2018 was linked to the National Death Index, with mortality follow-up through December 2019. The independent and joint associations of LWH (≥ 55 vs. < 55 h/week) and EAT-Lancet diet scores (low vs. high) with cardiometabolic outcomes and mortality were estimated using multivariable logistic and Cox proportional hazards models, respectively.

RESULTS

LWH was associated with higher odds of obesity (OR = 1.20; 95%CI = 1.07, 1.34) among all workers and higher CVD mortality among workers with high CVD risk at baseline (HR = 1.64, 95%CI = 0.79, 3.12). Low diet scores were associated with higher odds of obesity (OR = 1.34, 95%CI = 1.21, 1.42) and diabetes (OR = 1.33, 95%CI = 1.01, 1.76) among all workers. Working hours and diet scores were jointly associated with obesity and CVD mortality, indicating by the relative excess risk due to interaction greater than zero among all workers.

CONCLUSIONS

LWH and unhealthy diet are independent risk factors and may interact to exacerbate adverse cardiometabolic health outcomes.

The association between long working hours and obstructive sleep apnea assessed by STOP-BANG score: a cross-sectional study

PURPOSE

The relationship between night-shift work and obstructive sleep apnea (OSA) is well known, but that between OSA and long working hours is still unknown. This study explores the association between long working hours and OSA.

METHODS

Using cross-sectional Korean National Health and Nutrition Examination Survey 2020 data, we made multiple logistic regression models to calculate odds ratios (ORs) between weekly working hours and STOP-BANG scores for OSA screening. Stratified regression models by night or rotating shift work were also made.

RESULTS

In an adjusted model of STOP-BANG high-risk versus low-risk groups, the OR in the group exceeding 40 h/wk was higher but not statistically significant, 1.19 [95% confidence interval (CI) 0.66-2.15] compared to the group working 40 h/wk (standard working hours) or less. In the group exceeding 52 h/wk, the OR was 2.03 with statistical significance (95% CI 1.08-3.80). In the stratification analysis of daytime and night-shift work, the daytime worker results were similar to those in the non-stratified model. The point estimation values of ORs in the night-shift workers were higher than in the daytime workers; however, we did not observe a statistical significance.

CONCLUSION

Long working hours can increase the risk of OSA assessed by STOP-BANG scores.

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 and the Risk of Glucose Intolerance: A Cohort Study

Long working hours have negative effects on the health of workers. Several studies have reported the association between long working hours and both diabetes and prediabetes. Therefore, we aimed to examine the temporal relationship between long working hours and glucose intolerance. Our cohort study collected data from 25,803 healthy male participants at baseline. To evaluate the risk of incident glucose intolerance, we estimated the hazard ratios (HRs) and 95% confidence intervals (CIs) using the Cox proportional hazards regression analyses. During 77,605.0 person-years of follow-up, 6741 participants developed glucose intolerance. Multivariable-adjusted HRs (95% CI) for weekly working 41-52 and >52 h compared with working 35-40 h, were 1.28 (1.17-1.40) and 2.80 (2.54-3.09), respectively. In the dose-response analyses, long working hours had a nearly linear relationship with the development of glucose intolerance across most working hours per week. The association between long working hours and incident glucose intolerance was stronger in the younger-age subgroups than in the older-age subgroups (p for interaction <0.001). Our large-scale cohort study demonstrated that long working hours were associated with incident glucose intolerance, with a dose-response relationship.

Working for Long Hours Is Associated With Dietary Fiber Insufficiency

It has been suggested that long working hours are associated with various diseases through dietary patterns. However, few studies have reported the association between working hours and dietary habits. Thus, the objective of this cross-sectional study was to explore the difference in dietary fiber intake by working hours. Data of a total of 10,760 workers in South Korea who participated in the Korea National Health and Nutrition Survey (KNHANES), a nation-wide survey, were analyzed to determine different distributions of dietary fiber insufficiency using multiple logistic regression models. Fiber insufficiency proportion was different from working hour groups. 70.1% of the total population eat fiber insufficiently. Working &lt;40 h group showed 66.8% of fiber insufficiency. But working more than 52 h group marked 73.2% of fiber insufficiency. Logistic regression analysis of 10,760 nation-wide study participants revealed that working for 41–52 h a week (OR: 1.32, 95% CI: 1.18–1.47) and working for over 52 h a week (OR: 1.42, 95% CI: 1.25–1.62) were significantly associated with insufficient fiber intake compared to workers with standard working hours (30–40 h a week). These associations were still robust in an adjusted model, with working for 41–52 h a week (OR: 1.13, 95% CI: 1.01–1.27) and working for over 52 h (OR: 1.26, 95% CI: 1.09–1.45) showing high associations with dietary fiber insufficiency. Those with long working hours tend to have insufficient intake of dietary fiber. To promote desirable dietary habits, intervention programs on working conditions should be considered.

The effect of long working hours on developing type 2 diabetes in adults with prediabetes: The Kangbuk Samsung Cohort Study

Background

Long working hours are known to account for approximately one-third of the total expected work-related diseases, and much interest and research on long working hours have recently been conducted. Additionally, as the prevalence of prediabetes and the high-risk group for diabetes are increasing worldwide, interest in prediabetes is also rising. However, few studies have addressed the development of type 2 diabetes and long working hours in prediabetes. Therefore, the aim of this longitudinal study was to evaluate the relationship between long working hours and the development of diabetes in prediabetes.

Methods

We included 14,258 prediabetes participants with hemoglobinA1c (HbA1c) level of 5.7 to 6.4 in the Kangbuk Samsung Cohort Study. According to a self-reported questionnaire, we evaluated weekly working hours, which were categorized into 35–40, 41–52, and > 52 hours. Development of diabetes was defined as an HbA1c level ≥ 6.5%. Hazard ratios (HRs) and 95% confidence intervals (CIs) for the development of diabetes were estimated using Cox proportional hazards analyses with weekly working 35–40 hours as the reference.

Results

During a median follow-up of 3.0 years, 776 participants developed diabetes (incidence density, 1.66 per 100 person-years). Multivariable-adjusted HRs of development of diabetes for weekly working > 52 hours compared with working 35–40 hours were 2.00 (95% CI: 1.50–2.67). In subgroup analyses by age (< 40 years old, ≥ 40 years old), sex (men, women), and household income (< 6 million KRW, ≥ 6 million KRW), consistent and significant positive associations were observed in all groups.

Conclusions

In our large-scale longitudinal study, long working hours increases the risk of developing diabetes in prediabetes patients.