Impacts of lifestyle behavior and shift work on visceral fat accumulation and the presence of atherosclerosis in middle-aged male workers

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.

Shift Work as a Cardiovascular Disease Risk Factor: A Narrative Review

Shift work has emerged as a significant health concern in recent years, and research has revealed a link to circadian rhythm dysregulation and atherosclerosis, both of which can increase the risk of cardiovascular disease (CVD). Currently, there is a lack of updated reviews regarding the impact of shiftwork on CVD. Thus, the present narrative review aims to provide a comprehensive summary of the latest research on the relationship between shift work and CVD, identify potential gaps in the current knowledge, and highlight areas for future research. Database searches for peer-reviewed articles published between January 2013 to January 2023 on shift work associated CVD revealed many studies that found shift work is linked with increased prevalence of carotid artery plaque, increased arterial stiffness, and carotid artery intima-media thickness (IMT) all suggestive of a progression of atherosclerosis attributable to shift work. Hypertension, diabetes, and a sedentary lifestyle are known risks for CVD, and the results of the present study suggest that shift work should be added to that list. The elevation of inflammatory markers and DNA damage in shift workers may be linked to their increased progression of atherosclerosis and the positive association of shift work with coronary artery disease. There are minimal studies on mitigating approaches for shift work-related CVD, such as diet modification or exercise, emphasizing the need for further directed research in this area.

Circadian rhythms of risk factors and management in atherosclerotic and hypertensive vascular disease: Modern chronobiological perspectives of an ancient disease

Atherosclerosis, a chronic inflammatory disease of the arteries that appears to have been as prevalent in ancient as in modern civilizations, is predisposing to life-threatening and life-ending cardiac and vascular complications, such as myocardial and cerebral infarctions. The pathogenesis of atherosclerosis involves intima plaque buildup caused by vascular endothelial dysfunction, cholesterol deposition, smooth muscle proliferation, inflammatory cell infiltration and connective tissue accumulation. Hypertension is an independent and controllable risk factor for atherosclerotic cardiovascular disease (CVD). Conversely, atherosclerosis hardens the arterial wall and raises arterial blood pressure. Many CVD patients experience both atherosclerosis and hypertension and are prescribed medications to concurrently mitigate the two disease conditions. A substantial number of publications document that many pathophysiological changes caused by atherosclerosis and hypertension occur in a manner dependent upon circadian clocks or clock gene products. This article reviews progress in the research of circadian regulation of vascular cell function, inflammation, hemostasis and atherothrombosis. In particular, it delineates the relationship of circadian organization with signal transduction and activation of the renin-angiotensin-aldosterone system as well as disturbance of the sleep/wake circadian rhythm, as exemplified by shift work, metabolic syndromes and obstructive sleep apnea (OSA), as promoters and mechanisms of atherogenesis and risk for non-fatal and fatal CVD outcomes. This article additionally updates advances in the clinical management of key biological processes of atherosclerosis to optimally achieve suppression of atherogenesis through chronotherapeutic control of atherogenic/hypertensive pathological sequelae.

Shift Work and Early Arterial Stiffness: A Systematic Review

Shift work is a way of organizing rotating schedules throughout the day. This can include 1-3 shifts for the same person on a rotational basis with other workers. Schedules that include night work have been associated with cardiovascular risk, mainly due to circadian misalignment. This systematic review sought to determine whether shift work is a risk factor for increased arterial stiffness. A systematic review of different databases was performed, using the following keywords: work shift, night work, arteriosclerosis, vascular stiffness, arterial stiffness, pulse wave velocity, and their Medical Subject Headings. We selected and analyzed 11 articles regarding pulse wave velocity as an indicator of arterial stiffness. Two studies identified higher levels of arterial stiffness in shift workers compared to day workers, while two studies found the opposite. In addition, four studies found no differences in arterial stiffness between shifts, two studies associated shorter sleep duration with arterial stiffness, and one study observed that physical activity could prevent adverse cardiovascular outcomes in shift workers. The findings are heterogeneous and preclude any robust conclusions. However, the present review points to the need for further studies to investigate arterial stiffness in shift workers, with greater control for confounding factors and longitudinal design.

Association between rotating night shift work and carotid atherosclerosis among Chinese steelworkers: a cross-sectional survey

This study aimed to examine the association between rotating night shift work and carotid atherosclerosis in Chinese steelworkers. A total of 3582 subjects were included in this study. Different exposure metrics of night shifts, including current shift status, duration of night shifts (years), the cumulative number of night shifts (nights), cumulative length of night shifts (hours) and average frequency of night shifts (nights/month), were used to examine the relationship between night shift work and carotid atherosclerosis, including carotid plaque and carotid plaque scores. The prevalence of carotid plaque was 29.9% in the study population. Compared with day workers, significantly increased odds of carotid plaque were observed among shift workers in each quartile of the duration of night shifts after adjusting for potential confounders, especially in the third and fourth quartiles: odds ratio (OR) = 1.91, 95% confidence interval (CI): 1.46 to 2.49, in the third quartiles; OR = 1.69, 95% CI: 1.30 to 2.20, in the fourth quartiles. Positive associations of different exposure metrics of night shifts (continuous) with the odds of carotid plaque and the carotid plaque score were observed in the restricted cubic spline (RCS) models. No significant association was found in female workers between night shift work and carotid plaque. Rotating night shift work is associated with elevated odds of carotid atherosclerosis in male steelworkers.

Comparison of the usefulness of the cardio-ankle vascular index and augmentation index as an index of arteriosclerosis in patients with essential hypertension

Arteriosclerosis leads to various serious diseases that substantially reduce the quality of life. When treating hypertension, it is important to evaluate the degree of arteriosclerosis. In recent years, the cardio-ankle vascular index and augmentation index have been frequently used as indicators of arterial wall sclerosis. However, the superiority of either the cardio-ankle vascular index or the augmentation index as an index of arteriosclerosis remains unclear. Therefore, the present study compared the usefulness of these two indices as an index of arteriosclerosis. Associations between the cardio-ankle vascular index or augmentation index and risk factors for arteriosclerosis and other indices of arteriosclerosis in 535 consecutive patients with essential hypertension were evaluated. The cardio-ankle vascular index was significantly correlated with age, hemoglobin A1c, brain natriuretic peptide, and estimated glomerular filtration rate. In contrast, the augmentation index showed significant correlations only with age, brain natriuretic peptide, and estimated glomerular filtration rate. In addition, these correlations with the augmentation index were generally weaker than those with the cardio-ankle vascular index. The cardio-ankle vascular index, but not the augmentation index, was significantly correlated with flow-mediated dilation, an index of vascular endothelial function, and carotid intima-media thickness, an index of carotid atherosclerosis. Similar results were observed in subgroups stratified by sex and age. These data indicate that the cardio-ankle vascular index is more closely associated with risk factors for arteriosclerosis and other indices of arteriosclerosis than the augmentation index, suggesting that the cardio-ankle vascular index may be superior to the augmentation index as an index of arteriosclerosis.

Physical activity and sedentary behaviour in shift and non-shift workers: A systematic review and meta-analysis

Research examining the prevalence, physical activity (PA) and sedentary behaviour (SB) in shift workers show mixed results. This systematic review and meta-analysis aimed to compare PA and SB in shift workers with non-shift workers following the PRISMA guidelines. Ebscohost megafile ultimate (CINHAL, E-journals, Academic search ultimate, health source consumer edition, SPORT Discus), PubMed, Scopus, Web of Science, and Science Direct databases were searched up to April 2021. Cross-sectional and baseline data from longitudinal studies reporting PA and SB in full time workers were eligible. Data on participants characteristics and time spent in PA and SB and/or prevalence of workers meeting PA guidelines were extracted and pooled with random effects model. The Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) 10-item checklist was adapted and used. A total of 49 studies met inclusion criteria and 21 studies included for meta-analysis. The prevalence of meeting physical activity guidelines (OR 0.84, 95% CI: 0.68, 1.03) and standardized mean difference (SMD) of time spent in moderate-to-vigorous physical activity (SMD -0.1, 95% CI: -0.4, 0.20) were similar in shift and non-shift workers. Time spent in sedentary behaviour was lower in shift workers than non-shift workers (SMD -0.2, 95% CI: 0.50, -0.001). While the differences in PA are not so evident between shift and non-shift workers, the prevalence of sufficient PA was low in both groups. These preliminary findings provide support for inclusion of physical activity and sedentary behaviour in health promotion interventions targeted at shift workers.

Association between shift work and risk of metabolic syndrome: A systematic review and meta-analysis

AIMS

A comprehensive assessment of the association of shift work with risk of metabolic syndrome (MetS) through a systematic review and meta-analysis has not been reported. We aimed to evaluate the relationship from observational studies.

DATA SYNTHESIS

We searched PubMed, Embase, and Web of Science databases from inception to December 16, 2020. Articles were chosen according to established inclusion criteria. Studies with data on men and women and different types of shift work were treated as independent studies. Relative risks (RRs) and 95% confidence intervals (CIs) were pooled by using random-effects models with heterogeneity (I²) > 50%; otherwise, a fixed-effects model was used. A total of 7192 articles was searched from PubMed, Embase and Web of science. Finally, we included 23 articles (38 studies) in this meta-analysis. The pooled RRs and 95% CI of MetS risk with shift work, 1-shift work, 2-shift work, and 3-shift work versus non-shift work were 1.30 (95% CI 1.19-1.41), 0.95 (95% CI 0.82-1.11), 1.19 (95% CI 0.91-1.56) and 1.17 (95% CI 1.00-1.37), respectively. The results from subgroup analyses stratified by sex, age, and region supported our overall findings that shift work is a risk factor for MetS.

CONCLUSIONS

This meta-analysis suggests that shift work increases risk of MetS. Higher risk of MetS was found in the shift workers who were 2-shift or 3-shift or women or Asian workers.

Nuclear Receptors and Clock Components in Cardiovascular Diseases

Cardiovascular diseases (CVD) are still the first cause of death worldwide. Their main origin is the development of atherosclerotic plaque, which consists in the accumulation of lipids and inflammatory leucocytes within the vascular wall of large vessels. Beyond dyslipidemia, diabetes, obesity, hypertension and smoking, the alteration of circadian rhythms, in shift workers for instance, has recently been recognized as an additional risk factor. Accordingly, targeting a pro-atherogenic pathway at the right time window, namely chronotherapy, has proven its efficiency in reducing plaque progression without affecting healthy tissues in mice, thus providing the rationale of such an approach to treat CVD and to reduce drug side effects. Nuclear receptors are transcriptional factors involved in the control of many physiological processes. Among them, Rev-erbs and RORs control metabolic homeostasis, inflammatory processes and the biological clock. In this review, we discuss the opportunity to dampen atherosclerosis progression by targeting such ligand-activated core clock components in a (chrono-)therapeutic approach in order to treat CVD.

The Predictive Value of Carotid Ultrasonography With Cardiovascular Risk Factors-A "SPIDER" Promoting Atherosclerosis

Insufficient recommendations do not support the clinical use of carotid ultrasonography for further risk stratification in moderate-to-high risk patients with cardiovascular disease (CVD). A literature review was performed to assess six aspects of the research progress and limitations of carotid ultrasonography and carotid atherosclerosis-related risk factors: (1) structures of the carotid intima and media; (2) plaques; (3) inflammation; (4) dynamics of carotid blood flow; (5) early detection and intervention; and (6) risk factors for CVD. Although carotid intima-media thickness and carotid plaques are well-acknowledged independent predictors of CVD risk, normative and cut-off values are difficult to define due to the heterogeneous measurements reported in previous studies. Plaque properties, including location, number, density, and size, become more important risk predictors for cardiovascular disease, but a better approach for clinical use needs to be further established. Three-dimensional ultrasound and contrast-enhanced ultrasound are promising for promoting risk stratification with more details on plaque morphology. Moreover, inflammatory diseases and biomarkers should be evaluated for a full assessment of the inflammatory burden for atherosclerosis. Carotid flow velocity is not only an indicator for stenosis but also a potential risk predictor. Carotid atherosclerosis should be detected and treated early, and additional clinical trials are needed to determine the efficacy of these measures in reducing CVD risk. Cardiovascular risk factors tend to affect carotid plaques, and early treat-to-target therapy might yield clinical benefits. Based on the aforementioned six aspects, we consider that these six important factors act like a “SPIDER” spinning the web of atherosclerosis; a timely comprehensive assessment and intervention may halt the progression to CVD. Carotid ultrasound results should be combined with other atherosclerotic factors, and a comprehensive risk assessment may help to guide cardiovascular prevention decisions.

Sleep quality does not mediate the negative effects of chronodisruption on body composition and metabolic syndrome in healthcare workers in Ecuador

BACKGROUND AND AIMS

The objective of the present work was to determine to what extent sleep quality may mediate the association between chronodisruption (CD) and metabolic syndrome (MS), and between CD and body composition (BC).

METHODOLOGY

Cross-sectional study which included 300 adult health workers, 150 of whom were night shift workers and thereby exposed to CD. Diagnosis of MS was made based on Adult Treatment Panel III criteria. Sleep quality was measured using the Pittsburgh Sleep Quality Index. Body mass index (BMI), fat mass percentage, and visceral fat percentage were measured as indicators of body composition (BC). Data were analyzed using logistic, linear regression and structural equation models.

RESULTS

The odds of health workers exposed to CD to suffer MS was 22.13 (IC₉₅ 8.68-66.07) when the model was adjusted for age, gender, physical activity and energy consumption. CD was also significantly associated with an increase in fat mass and visceral fat percentages, but not to BMI. Surprisingly, there was not enough evidence supporting the hypothesis that sleep quality contributes to the association between CD and MS or between CD and BC.

CONCLUSIONS

Sleep quality does not mediate the negative effects of CD on MS nor on BC.

New Horizons of Arterial Stiffness Developed Using Cardio-Ankle Vascular Index (CAVI)

Arterial stiffness is recognized mainly as an indicator of arteriosclerosis and a predictor of cardiovascular events. Cardio-ankle vascular index (CAVI), which reflects arterial stiffness from the origin of the aorta to the ankle, was developed in 2004. An important feature of this index is the independency from blood pressure at the time of measurement. A large volume of clinical evidence obtained using CAVI has been reported. CAVI is high in patients with various atherosclerotic diseases including coronary artery disease and chronic kidney disease. Most coronary risk factors increase CAVI and their improvement reduces CAVI. Many prospective studies have investigated the association between CAVI and future cardiovascular disease (CVD), and proposed CAVI of 9 as the optimal cut-off value for predicting CVD. Research also shows that CAVI reflects afterload and left ventricular diastolic dysfunction in patients with heart failure. Furthermore, relatively acute changes in CAVI are observed under various pathophysiological conditions including mental stress, septic shock and congestive heart failure, and in pharmacological studies. CAVI seems to reflect not only structural stiffness but also functional stiffness involved in acute vascular functions. In 2016, Spronck and colleagues proposed a variant index CAVI₀, and claimed that CAVI₀ was truly independent of blood pressure while CAVI was not. This argument was settled, and the independence of CAVI from blood pressure was reaffirmed. In this review, we summarize the recently accumulated evidence of CAVI, focusing on the proposed cut-off values for CVD events, and suggest the development of new horizons of vascular function index using CAVI.

Close Association between Subclinical Atherosclerosis and Pulmonary Function in Middle-Aged Male Smokers

AIMS

Cigarette smoking provokes deleterious influences on cardiovascular and pulmonary systems, although the underlying relationship has not been sufficiently investigated especially in early-stage disease. The present study investigated possible associations between subclinical atherosclerosis and pulmonary function in middle-aged male smokers.

METHODS

Male smokers undergoing their periodic health check-up were enrolled in this study (n=3,775, 45±8 years). Pulmonary function was evaluated using spirometry by calculating forced vital capacity (FVC) as a percentage of predicted value (FVC%-predicted), forced expiratory volume in one second (FEV1) as a percentage of predicted value (FEV1%-predicted), and the ratio of FEV1 to FVC (FEV1/FVC). Subclinical atherosclerosis was assessed based on ankle-brachial pressure index (ABI), cardio-ankle vascular index (CAVI), ultrasound examination of the carotid intima-media thickness (IMT), and presence of plaque.

RESULTS

Multivariate regression analysis showed that ABI was positively associated with FVC%-predicted and FEV1%-predicted after adjustment for confounders including smoking intensity, while CAVI or carotid IMT was inversely associated with both. Participants with chronic obstructive pulmonary disease (COPD, n=256) showed reduced ABI and increased CAVI or carotid IMT compared with those without COPD, and participants with carotid plaque had lower pulmonary function than those without plaque. Reduced FEV1/FVC was an independent determinant of carotid plaque and decreased ABI was an independent determinant of COPD, as revealed by logistic regression analysis with the endpoint of carotid plaque presence or a diagnosis of COPD revealed.

CONCLUSIONS

Middle-aged male smokers showed a close association between subclinical atherosclerosis and pulmonary function, implying that smoking induced-vascular and pulmonary damage are interacting in early-stage disease.