Factors affecting common carotid artery intima-media thickness in male workers aged 45 years

Introduction
Common carotid artery intima-media thickness (CCA-IMT) can be used as a surrogate marker for cardiovascular health. Only a few studies have investigated the effect of job stress and overwork on early atherosclerotic disease. This study examined the relationship between cardiovascular disease (CVD) risk factors, job stress, overwork and CCA-IMT in a Japanese population sample.

Methods
Between 2007 and 2011, Hitachi Health Care Center recruited 1924 male workers aged 45 years. CCA-IMT was measured using B-mode ultrasonography and the mean bilateral values were calculated. The traditional risk factors for CVD, including body mass index (BMI), lipid and glucose metabolism, blood pressure, and smoking status, were assessed. The brief job stress questionnaire (BJSQ) was used to determine job stress, i.e., job demands, job control, supervisor support, and coworker support. To evaluate job demands, we calculated the quantitative job overload scores (3 items). Supervisor support and coworker support were measured using a 3-item scale score. The data for the developed CCA-IMT (>1.0 mm) group were compared with those for the lesser CCA-IMT (≤1.0 mm) group. We used logistic regression analysis after selecting variables by stepwise regression analysis.

Results
The odds ratios for the development of CCA-IMT were 1.11(95% confidence interval, 1.02–1.20) for BMI, 1.07(1.03–1.10) for systolic blood pressure, 1.61(1.32–1.92) for HbA1c level, 2.02(1.48–2.72) for low-density lipoprotein/high-density lipoprotein ratio, and 1.29(1.06–1.57) for lower coworker support, respectively.

Discussion
In addition to the traditional risk factors of CVD, lower coworker support was found to be significantly associated with the development of subclinical atherosclerosis, suggesting that enhanced coworker support is important for preventing atherosclerosis.