Comparison of peripheral endothelial function in shift versus nonshift workers

The effect of shift work on body mass index: A systematic review and meta-analysis of observational studies

CONTEXT

Shift work involves working outside the standard working hours of 9 am to 5 pm Monday to Friday and may include working evening, night, weekend, or rotating shift patterns. Since shift workers sleep less and their circadian rhythms are disrupted, they are reported to have higher body weight than day workers.

OBJECTIVE

This meta-analysis aims to determine whether shift workers (SW) are more prone to higher body mass index (BMI) than their day workers (DW) counterparts. It also addresses the question of whether the duration of shift work exposure, sex, or occupational type affect BMI value.

METHODS

Four databases that is PubMed, EBSCO Host, Scopus, and Web of Science were searched for reports published up to October 2023.

RESULTS

Sixty-three studies involving a total of 693 449 participants met our inclusion criteria. Meta-analyses showed a significant effect of shift work on BMI value (standard mean difference; SMD: 0.10 kg/m2 [95% confidence interval; 95% CI: 0.07; 0.13; p < .001]) as compared with non-shift counterparts. Subgroup analysis revealed that shift work significantly increased BMI for studies where male working on this job schedule (SMD: 0.10 kg/m2 [95% CI: 0.04; 0.17; p = .0018]) for studies where shift workers worked ≥13 years (calculated as the median of shift work experience; SMD: 0.14 kg/m2 [95% CI: 0.10; 0.18; p < .001]) as well as for studies where industrial (SMD: 0.12 kg/m2 [95% CI: 0.05; 0.19; p = .0012]) and other type of occupations were dominated (0.12 kg/m2 [95% CI: 0.07; 0.16; p < .001]).

CONCLUSIONS

We found that in general working on a shift schedule increases BMI as compared with day workers, especially in case of male employed in this job schedule, for shift workers working for long periods of time (≥13 years), and for shift workers employed in industry and other type of occupations(e.g., airline workers, firefighters, police officers, blue collar, security personnel, bus drivers, garbage collectors, railway workers, postal, oil and gas workers).

Acute Effect of Night Shift Work on Endothelial Function with and without Naps: A Scoping Review

We examined the breadth and depth of the current evidence investigating napping/sleeping during night shift work and its impact on non-invasive measures of endothelial function. We used a scoping review study design and searched five databases: Ovid Medline, EMBASE, Ovid APA PsycInfo, Web of Science Core Collection, and EBSCO CINAHL. We limited our search to English language and publications from January 1980 to September 2022. Our reporting adhered to the PRISMA-ScR guidance for scoping reviews. Our search strategy yielded 1949 records (titles and abstracts) after deduplication, of which 36 were retained for full-text review. Five articles were retained, describing three observational and two experimental research studies with a total sample of 110 individuals, which examined the non-invasive indicators of endothelial function in relation to the exposure to night shift work. While there is some evidence of an effect of night shift work on the non-invasive indicators of endothelial function, this evidence is incomplete, limited to a small samples of shift workers, and is mostly restricted to one measurement technique for assessing endothelial function with diverse protocols. In addition, there is no identifiable research investigating the potential benefits of napping during night shift work on non-invasive measures of endothelial function.

The Impact of Different Types of Shift Work on Blood Pressure and Hypertension: A Systematic Review and Meta-Analysis

Shift work (SW) encompasses 20% of the European workforce. Moreover, high blood pressure (BP) remains a leading cause of death globally. This review aimed to synthesize the magnitude of the potential impact of SW on systolic blood pressure (SBP), diastolic blood pressure (DBP) and hypertension (HTN). MEDLINE, EMBASE and CENTRAL databases were searched for epidemiological studies evaluating BP and/or HTN diagnosis among shift workers, compared with day workers. Random-effects meta-analyses were performed and the results were expressed as pooled mean differences or odds ratios and 95% confidence intervals (95% CI). The Newcastle-Ottawa Scale was used to assess the risk of bias. Forty-five studies were included, involving 117,252 workers. We found a significant increase in both SBD and DBP among permanent night workers (2.52 mmHg, 95% CI 0.75-4.29 and 1.76 mmHg, 95% CI 0.41-3.12, respectively). For rotational shift workers, both with and without night work, we found a significant increase but only for SBP (0.65 mmHg, 95% CI 0.07-1.22 and 1.28 mmHg, 95% CI 0.18-2.39, respectively). No differences were found for HTN. Our findings suggest that SW is associated with an increase of BP, mainly for permanent night workers and for SBP. This is of special interest given the large number of susceptible workers exposed over time.

The relationship between forearm skin speed-resolved perfusion and oxygen saturation, and finger arterial pulsation amplitudes, as indirect measures of endothelial function

OBJECTIVE

Endothelial function is important for regulating peripheral blood flow to meet varying metabolic demands and can be measured indirectly during vascular provocations. In this study, we compared the PAT finger response (EndoPAT) after a 5-minutes arterial occlusion to that from forearm skin comprehensive microcirculation analysis (EPOS).

METHODS

Measurements in 16 subjects with varying cardiovascular risk factors were carried out concurrently with both methods during arterial occlusion, while forearm skin was also evaluated during local heating.

RESULTS

Peak values for EPOS skin Perf_conv and speed-resolved total perfusion after the release of the occlusion were significantly correlated to the EndoPAT RHI (ρ = .68, P = .007 and ρ = .60, P = .025, respectively), mainly due to high-speed blood flow. During local heating, EPOS skin oxygen saturation, SO2, was significantly correlated to RHI (ρ = .62, P = .043). This indicates that SO2 may have diagnostic value regarding endothelial function.

CONCLUSIONS

We have demonstrated for the first time a significant relationship between forearm skin microcirculatory perfusion and oxygen saturation and finger PAT. Both local heating and reactive hyperemia are useful skin provocations. Further studies are needed to understand the precise regulation mechanisms of blood flow and oxygenation during these tests.

Association of Subjective and Objective Sleep Duration as well as Sleep Quality with Non-Invasive Markers of Sub-Clinical Cardiovascular Disease (CVD): A Systematic Review

Aim: Abnormal daily sleep duration and quality have been linked to hypertension, diabetes, stroke, and overall cardiovascular disease (CVD) morbidity & mortality. However, the relationship between daily sleep duration and quality with subclinical measures of CVD remain less well studied. This systematic review evaluated how daily sleep duration and quality affect burden of subclinical CVD in subjects free of symptomatic CVD.

Methods: Literature search was done via MEDLINE, EMBASE, Web of Science until June 2016 and 32 studies met the inclusion criteria. Sleep duration and quality were measured either via subjective methods, as self-reported questionnaires or Pittsburg Sleep Quality Index (PSQI) or via objective methods, as actigraphy or polysomnography or by both. Among subclinical CVD measures, coronary artery calcium (CAC) was measured by electron beam computed tomography, Carotid intima-media thickness (CIMT) measured by high-resolution B-mode ultrasound on carotid arteries, endothelial/microvascular function measured by flow mediated dilation (FMD) or peripheral arterial tone (PAT) or iontophoresis or nailfold capillaroscopy, and arterial stiffness measured by pulse wave velocity (PWV) or ankle brachial index (ABI).

Results: Subjective short sleep duration was associated with CAC and CIMT, but variably associated with endothelial dysfunction (ED) and arterial stiffness; however, subjective long sleep duration was associated with CAC, CIMT and arterial stiffness, but variably associated with ED. Objective short sleep duration was positively associated with CIMT and variably with CAC but not associated with ED. Objective long sleep duration was variably associated with CAC and CIMT but not associated with ED. Poor subjective sleep quality was significantly associated with ED and arterial stiffness but variably associated with CAC and CIMT. Poor objective sleep quality was significantly associated with CIMT, and ED but variably associated with CAC.

Conclusions: Overall, our review provided mixed results, which is generally in line with published literature, with most of the studies showing a significant relationship with subclinical CVD, but only some studies failed to demonstrate such an association. Although such mechanistic relationship needs further evaluation in order to determine appropriate screening strategies in vulnerable populations, this review strongly suggested the existence of a relationship between abnormal sleep duration and quality with increased subclinical CVD burden.

Shiftwork and decline in endothelial function among police officers

BACKGROUND

Our objective was to assess the influence of shiftwork on change in endothelial function.

METHODS

This longitudinal study was conducted in 188 police officers (78.2% men). Shiftwork status (day, afternoon, night) was assessed objectively using daily Buffalo, NY payroll work history records. Brachial artery flow-mediated dilation (FMD) was assessed using ultrasound. Mean change in FMD% between 2004-2009 and 2010-2015 was compared across shiftwork using analysis of variance/covariance.

RESULTS

Overall, mean FMD% decreased from 5.74 ± 2.83 to 3.88 ± 2.11 over an average of 7 years among all officers; P < 0.0001. Effect modification by gender was significant. Among men (but not women), those who worked day shifts had a smaller mean (±SE) decrease in FMD% (-0.89 ± 0.35) compared with those who worked the afternoon (-2.69 ± 0.39; P = 0.001) or night shifts (-2.31 ± 0.45; P = 0.020) after risk factor adjustment.

CONCLUSIONS

Larger declines in endothelial function were observed among men who worked afternoon or night shifts. Further investigation is warranted. Am. J. Ind. Med. 59:1001-1008, 2016. Published 2016. This article is a U.S. Government work and is in the public domain in the USA.

Current and cumulative night shift work and subclinical atherosclerosis: results of the Gutenberg Health Study

PURPOSE

The study examines the association between exposure to current and cumulative night shift work and subclinical parameters of atherosclerosis.

METHODS

Participants of a population-based cohort study (the Gutenberg Health Study, N = 15,010) aged 35-64 years were examined at baseline (2007-2012). Investigations included measurements of arterial stiffness, vascular function [reactive hyperaemia (RH) index], and intima media thickness (IMT). Also, a complete job history (including up to 15 periods), occupational exposures, a variety of lifestyle, and dispositional variables were enquired.

RESULTS

Night shift work was performed by 1071 out of 8065 currently employed individuals. The strongest association after adjustment for age, sex, job complexity level, being a manager, overtime work, and noise appeared for more than 660 night shifts within the last 10 years and a significantly increased arterial stiffness of 0.33 m/s. This reflects a 4 % flow velocity increase for individuals with more than 660 night shifts compared to non-night workers. Regarding the entire professional life, night shift workers showed a significantly decreased vascular function by -0.054 RH index points by using the same adjustment. IMT values did not differ statistically from non-night workers. Lifestyle and dispositional factors showed an influence on all used subclinical atherosclerosis parameters.

CONCLUSIONS

The cross-sectional results demonstrate an association between night work and detrimental changes in the atherosclerotic process. The association is more pronounced with more years in night shift and is partly explained by lifestyle and dispositional factors. Longitudinal analyses are necessary to confirm the results.

Associations of work hours, job strain, and occupation with endothelial function: the Multi-Ethnic Study of Atherosclerosis (MESA)

OBJECTIVE

To investigate associations of work hours, job control, job demands, job strain, and occupational category with brachial artery flow-mediated dilation (FMD) in 1499 Multi-Ethnic Study of Atherosclerosis participants.

METHODS

Flow-mediated dilation was obtained using high-resolution ultrasound. Mean values of FMD were examined across categories of occupation, work hours, and the other exposures using regression analyses.

RESULTS

Occupational category was significantly associated with FMD overall, with blue-collar workers showing the lowest mean values-management/professional = 4.97 ± 0.22%; sales/office = 5.19 ± 0.28%; services = 4.73 ± 0.29%; and blue-collar workers = 4.01 ± 0.26% (adjusted P < 0.001). There was evidence of effect modification by sex (interaction P = 0.031)-significant associations were observed among women (adjusted P = 0.002) and nearly significant results among men (adjusted P = 0.087). Other exposures were not significantly associated with FMD.

CONCLUSIONS

Differences in endothelial function may account for some of the variation in cardiovascular disease across occupational groups.

Sleep Deficiency and Deprivation Leading to Cardiovascular Disease

Sleep plays a vital role in an individual's mental, emotional, and physiological well-being. Not only does sleep deficiency lead to neurological and psychological disorders, but also the literature has explored the adverse effects of sleep deficiency on the cardiovascular system. Decreased quantity and quality of sleep have been linked to cardiovascular disease (CVD) risk factors, such as hypertension, obesity, diabetes, and dyslipidemia. We explore the literature correlating primary sleep deficiency and deprivation as a cause for cardiovascular disease and cite endothelial dysfunction as a common underlying mechanism.

Prognostic value of peripheral arterial tonometry in patients with coronary artery disease and a high cardiovascular risk profile

AIM

Data regarding the prognostic value of peripheral endothelial function testing in patients with cardiovascular disease are conflicting. Peripheral arterial tonometry(PAT) is increasingly used to measure the peripheral endothelial function. The prognostic value of this method has not been investigated thus far in patients with cardiovascular disease and/or a high cardiovascular risk profile.

METHODS

In 96 patients with significant coronary artery disease(CAD) or＜70% stenosis and ≥ three cardiovascular risk factors, reactive hyperemia was induced following upper arm occlusion and the PAT-ratio between baseline and hyperemia was calculated. The patients were followed for cardiovascular events(revascularization, acute coronary syndrome, ischemic stroke, cardiovascular death, repeat coronary angiography due to chest pain) for 44±14 months. The first event was included in the combined end point.

RESULTS

The study cohort was divided according to the median PAT-ratio(1.91). The combined end point occurred in 14 patients with a PAT-ratio below the median(1.91) and in 12 patients with a PAT-ratio of ≥1.91 (p=0.65). In a subgroup of 76 patients, the PAT-ratio was reassessed after six months. No differences in the event rate were found between the patients who exhibited deterioration(n=50) and those who exhibited an improvement in the PAT-ratio of ＞0.1(n=26; 22 vs. 32%, p=0.32). The combined end point occurred earlier in the patients with a PAT-ratio within the 1st tertile than in those with a PAT-ratio within the 2nd/3rd tertile(11.3±11.0 vs. 27.5±18.6 months, p=0.03).

CONCLUSIONS

In patients with established CAD or a high cardiovascular risk profile, the PAT-ratio cannot be used to predict the risk of future cardiovascular events. However, a lower PAT-ratio may be associated with the earlier occurrence of cardiovascular events.

Endothelial Dysfunction: An Early Cardiovascular Risk Marker in Asymptomatic Obese Individuals with Prediabetes

AIMS: To elucidate if endothelial dysfunction is an early CV risk marker in obese men and women with prediabetes. STUDY DESIGN: Cross-sectional study. PLACE AND DURATION OF STUDY: Clinical Research Unit, Pennington Biomedical Research Center, Baton Rouge, LA. United States. METHODOLOGY: Overweight and obese status denotes an increasing adipose tissue burden which spills over into ectopic locations, including the visceral compartment, muscle and liver. Associated co-morbidities enhance cardiovascular (CV) risk. Endothelium which is the largest receptor-effector end-organ in our bodies, while responding to numerous physical and chemical stimuli maintains vascular homeostasis. Endothelial dysfunction (ED) is the initial perturbation, which precedes fatty streak known to initiate atherosclerosis: insidious process which often culminates as sudden catastrophic CV adverse event. Asymptomatic men and women; [n=42] coming in after an overnight fast had demographic, anthropometric, clinical chemistry and resting endothelial function [EF: increased test finger peripheral arterial tone (PAT) relative to control; expressed as relative hyperemia index (RHI)] assessments. RESULTS: Adults with desirable weight [n=12] and overweight [n=8] state, had normal fasting plasma glucose [Mean(SD)]: FPG [91.1(4.5), 94.8(5.8) mg/dL], insulin [INS, 2.3(4.4), 3.1(4.8) μU/ml], insulin sensitivity by homeostasis model assessment [HOMA-IR, 0.62(1.2), 0.80(1.2)] and desirable resting clinic blood pressure [SBP/DBP, 118(12)/74(5), 118(13)/76(8) mmHg]. Obese adults [n=22] had prediabetes [FPG, 106.5(3.5) mg/dL], hyperinsulinemia [INS 18.0(5.2) μU/ml], insulin resistance [HOMA-IR 4.59(2.3)], prehypertension [PreHTN; SBP/DBP 127(13)/81(7) mmHg] and endothelial dysfunction [ED; reduced RHI 1.7(0.3) vs. 2.4(0.3); all p<0.05]. Age-adjusted RHI correlated with BMI [r=-0.53; p<0.001]; however, BMI-adjusted RHI was not correlated with age [r=-0.01; p=0.89]. CONCLUSION: Endothelial dysfunction reflective of cardiometabolic changes in obese adults can be an early risk marker for catastrophic CV events.

Job strain and shift work influences on biomarkers and subclinical heart disease indicators: a pilot study

This pilot study is one of the first to examine the impact of job strain and shift work on both the autonomic nervous system (ANS) and the hypothalamic-pituitary-adrenal (HPA) axis using two salivary stress biomarkers and two subclinical heart disease indicators. This study also tested the feasibility of a rigorous biological sampling protocol in a busy workplace setting. Paramedics (n = 21) self-collected five salivary samples over 1 rest and 2 workdays. Samples were analyzed for α-amylase and cortisol diurnal slopes and daily production. Heart rate variability (HRV) was logged over 2 workdays with the Polar RS800 Heart Rate monitors. Endothelial functioning was measured using fingertip peripheral arterial tonometry. Job strain was ascertained using a paramedic-specific survey. The effects of job strain and shift work were examined by comparing paramedic types (dispatchers vs. ambulance attendants) and shift types (daytime vs. rotating day/night). Over 90% of all expected samples were collected and fell within expected normal ranges. Workday samples were significantly different from rest day samples. Dispatchers reported higher job strain than ambulance paramedics and exhibited reduced daily alpha-amylase production, elevated daily cortisol production, and reduced endothelial function. In comparison with daytime-only workers, rotating shift workers reported higher job strain, exhibited flatter α-amylase and cortisol diurnal slopes, reduced daily α-amylase production, elevated daily cortisol production, and reduced HRV and endothelial functioning. Despite non-statistically significant differences between group comparisons, the consistency of the overall trend in subjective and objective measures suggests that exposure to work stressors may lead to dysregulation in neuroendocrine activity and, over the long-term, to early signs of heart disease. Results suggest that further study is warranted in this population. Power calculations based on effect sizes in the shift type comparison suggest a study size of n = 250 may result in significant differences at p = 0.05. High compliance among paramedics to complete the intensive protocol suggests this study will be feasible in a larger population.

Effect of shift work on endothelial function in young cardiology trainees

BACKGROUND

Long-term shift work (SW) is associated with an increase in cardiovascular disease (CVD). Previous studies have shown that prolonged SW is associated with endothelial dysfunction, suggesting that this abnormality may contribute to the SW-related increase in cardiovascular risk. The immediate effect of SW on endothelial function in healthy subjects, however, is unknown.

DESIGN

We studied endothelial function and endothelium-independent function in 20 healthy specialty trainees in cardiology at our Institute, without any cardiovascular risk factor (27.3 ± 1.9 years, nine males), at two different times: (1) after a working night (WN), and (2) after a restful night (RN). The two test sessions were performed in a random sequence.

METHODS

Endothelial function was assessed by measuring brachial artery dilation during post-ischaemic forearm hyperaemia (flow-mediated dilation, FMD). Endothelium-independent function in response to 25 µg of sublingual glyceryl trinitrate (nitrate-mediated dilation, NMD) was also assessed.

RESULTS

FMD was 8.02 ± 1.4% and 8.56 ± 1.7% after WN and RN, respectively (p = 0.025), whereas NMD was 10.5 ± 2.1% and 10.4 ± 2.0% after WN and RN, respectively (p = 0.48). The difference in FMD between WN and RN was not influenced by the numbers of hours slept during WN (<4 vs >4 hours) and by the duration of involvement of specialty trainees in nocturnal work (<12 vs >12 months).

CONCLUSIONS

Our study shows that in healthy medical residents, without any cardiovascular risk factor, FMD is slightly impaired after WN compared to RN. Disruption of physiological circadian neuro-humoral rhythm is likely to be responsible for this adverse vascular effect.