Association between Job Stress on Heart Rate Variability and Metabolic Syndrome in Shipyard Male Workers

Abstract

A growing body of literature has documented that job stress is associated with the development of cardiovascular disease. Nevertheless, the pathophysiological mechanism of this association remains unclear. The purpose of this study is to elucidate the relationship between job stress, heart rate variability, and metabolic syndrome. The study design was cross-sectional, and a total of 169 industrial workers were recruited. A structured-questionnaire was used to assess the general characteristics and job characteristics (work demand, decision latitude). Heart rate variability (HRV) was recorded using SA-2000 (medi-core), and was assessed by time-domain and by frequency-domain analyses. Time domain analysis was performed using SDNN (Standard Deviation of normal to normal interval), and spectral analysis using low-frequency (LF), high-frequency (HF), and total frequency power. Metabolic syndrome was defined on the basis of risk factors being clustered when three or more of the following cardiovascular risk factors were included in the fifth quintile: glucose, systolic blood pressure, high-density lipoprotein cholesterol (bottom quintile), triglyceride, and waist-hip ratio. The results showed that job characteristics were not associated with cardiovascular risk factors. Compared to the lower strain group (low strain+passive+active group), the high strain group had a less favorable cardiovascular risk profile with higher levels of blood pressure, glucose, homocysteine, and clotting factor, but the difference was not statistically significant. The SDNN of HRV was significantly lower in the high strain group than in the low strain group. The prevalence of metabolic syndrome in the lower strain group and high strain group was 13.2% and 23.8%, respectively. In the high strain group, the metabolic syndrome was significantly related to a decreased SDNN. However, we could not find a significant association in LF/HF ratio. This result suggests that decreased HRV found in the high-strain group are not a direct indicator of disease. However, it can induce cardiovascular abnormalities or dysfunctions related to the onset of heart disease among high risk groups.

Occupational stress and cardiovascular disease

“…Job strain is strongly associated with rates of metabolic syndrome (Kang, et al, 2004); this relationship follows a dose-response function (Chandola, Brunner, & Marmot, 2006). However, women with low long-term job strain were reported to have high levels of metabolic syndrome, whereas men with high long-term job strain showed low levels of metabolic syndrome (Kinnunen, Feldt, Kinnunen, Kaprio, & Pulkkinen, 2006).…”

Adverse effects of psychosocial work factors on blood pressure: systematic review of studies on demand–control–support and effort–reward imbalance models

“…Confounding might also be present in other studies due to a lack of control for cardiovascular risk factors. For example, some studies did not control for age (125,132,144,146,174) or family history of CVD (61 studies) (23, 44, 124-129, 131-141, 153, 155-159, 161-168, 171, 174, 178, 180, 181, 183, 185-189, 192-194, 214, 223, 224) (tables A-C), which constitute major risk factors for high BP. Residual confounding might also have resulted from the fact that none of the studies on job strain controlled for ERI or vice-versa.…”

Description of a large-scale study design to assess work-stress-disease associations for cardiovascular disease

“…A lot of variation exists in the occupational profile of the study samples. While some studies included workers with a wide variety of occupational titles [29,31,33,34], other studies were based on homogeneous occupational samples [26][27][28]35]. As for the gender distribution, a large number of studies investigating stress and heart rate variability included only male subjects [26,27,29,31,32,35], while some other studies were based on mixed gender samples [25,30,33,34] or a strictly female sample [27].…”

“…A more comprehensive assessment of low social control in several major socio-economic domains is lacking. A number of studies have examined work-related stress in relation to heart rate variability [26][27][28][29][30][31]. Only rarely some studies have additionally investigated the social co-risk factors such as social network and social support or social economic risks [32][33][34].…”

“…Many bio-monitoring technologies have multiple parameters that can affect measurement accuracy which are left to vary across studies. Several studies have examined the associations between work stress and heart rate variability based on 5-or 3-minute ECG recordings [25,28,32,33,35], while other studies included measures from 24-hour ambulatory monitoring [26,27,[29][30][31]34]. The results obtained from short-term ECG recordings are difficult to compare with the findings based on 24-hour monitoring because the interpretation of heart rate variability measures depends fundamentally on the length of the recording period according to he Task Force of the European Society of Cardiology and the North American Society of Pacing and Electrophysiology [36].…”