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

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.

Current Status of Hospital-based Health Promotion Programs in Korea and the Factors Influencing Their Introduction / 예방의학회지

OBJECTIVES: To investigate the current status of hospital-based health promotion programs in Korea and to elucidate the factors which affect to the process of implementation. METHODS: We conducted a mail survey of all 875 hospitals in Korea from March to May 2001. In reference to 12 specific kinds of health promotion programs, hospital CEOs were asked whether their hospital have such programs, whether they are fully staffed and whether the program is paid for by the patients. Contextual factors(location, hospital type, number of beds, length of operation, public/private status, economic level of the community, the level of competition) and organizational factors (the extent of market, compatibility with vision, formalization), strategic types of the CEOs (defender/analyser/prospector) were also surveyed. The relationships between each variable and the implementation of health promotion services, activation of services, and the target groups(patient/community resident) were analyzed by univariate analysis and the independent effects of these variables were examined with multiple logistic regression. RESULTS: 106 of 125 hospitals responding (84.8%) had more than one health promotion program. However, they showed fluctuations in the adoption rate of each programs, meaning that comprehensive health promotion services were not provided. Many programs were not fully staffed and few hospitals had paid programs. In factors affecting health promotion service implementation, private hospitals showed a higher rate in implementation than public hospitals. In contrast, when the competition among nearby hospitals was intense, the level of implementation of service lowered. In the strategic type of the CEOs, the prospectors were shown to have instituted more health promotion programs in their hospitals and the analysers had a greater tendency to have programs for community residents than the defenders. CONCLUSION: Considering the above results, contextual factors may contribute greatly to the introduction of health promotion services in Korean hospital, although the CEO's personal preference and organizational factors play a larger role in the activation of services. Additionally, the CEO's personal preference may be the major influencing factor in the introduction of programs for community residents.

Meta-analysis of hypertension as a risk factor of cerebrovascular disorders in Koreans

This study was conducted to integrate the results of previous studies which evaluated hypertension as a risk factor for cerebrovascular disorders (CVD) in Koreans. We retrieved the Korean literature using a manual search and the English literature using the MEDLINE database concerning the relationship between hypertension and CVD in Koreans from 1980 to 1997. The overall effect size of hypertension as a risk factor of CVD was represented by common odds ratio (OR). Before the integration of each effect size, a heterogeneity test and a sensitivity test was conducted. The materials were nine published epidemiologic studies with a total of 2,271 cases of CVD. The common ORs (95% confidence interval) of overall CVD, hemorrhagic CVD and ischemic CVD associated with hypertension were 4.10 (3.56-4.71), 6.56 (4.92-8.80) and 3.28 (2.77-3.90), respectively. Thus, the common OR of hemorrhagic CVD associated with hypertension was significantly higher than that of overall or ischemic CVD. This suggests that hypertension is an important risk factor for overall CVD and its subtypes in Koreans. Due to the lack of reliable prospective studies, however, longitudinal study is required in this area.

What Factors Affect Mortality over the Age of 40? / 예방의학회지

OBJECTIVES: This study was conducted to identify the factors influencing the mortality of Koreans over the age of 40 by a nested case-control study. METHODS: The cohort consisted of the beneficiaries of Korea Medical Insurance Corporation for Government Employees & Private School Teachers and Staff(KMIC) who received health examinations of KMIC in 1992 and 1993 retrospectively. At that time, they were more than 40 years old. The cases were 19,258 cohort members who had died until December 31, 1997. The controls were 19,258 cohort members who were alive until December 31, 1997. Controls were matched with age and sex distribution of the cases. The data used in this study were the funeral expenses requesting files, and the files of health examinations and health questionnaires gathered in 1992 and 1993. To assess the putative risk factors of death, student t-test, chi-square test, multiple logistic regression analysis were used. RESULTS: In multiple logistic regression analysis, independent risk factors of death were as follows; systolic blood pressure, diastolic blood pressure, blood glucose, AST, urine glucose, urine protein, alcohol drinking(frequency), cigarette smoking and perceived health status, intake of restoratives and blood transfusion showed positive associations with death; coffee consumption showed negative associations with death; and body mass index and serum total cholesterol showed J-shaped association with death. CONCLUSIONS: Regarding the direction of association, the result of analysis on the data restricted to '96-'97 was same as that of '93-'97. But in some variables such as obesity, serum cholesterol, the odds ratios of death in the data of '96-'97 were higer than those of '93-'94, which suggested that the data of '93-'94 was bearing effect-cause relationship. We concluded that it suggested further researches using long-term follow-up data to be needed in this area.

The Assessment of Worker's Health Status by SF-36 / 대한산업의학회지

This study was conducted to understand health status by general characteristic, and to find out relationship between social support and worker's health status. Health status was measured using SF-36(Medical Outcome Study Short Form 36), a 36 item self administered Instrument. The finding of this study were as follow; Mean scores of health status by sex were higher in male. The younger worker reported good health on physical functioning and role limitation-physical than did the older worker, but the older worker reported good health on social functioning and mental health. Mean scores of health status were higher in high income and white worker. When the relationship between social support and health status, social functioning, role limitation-emotion, mental health, vitality, general health were significantly related. Therefore we reviewed the evidence that socio-economic condition are associated with health status in this study, and that the strength of the social support was a important to maintain health.

Effects of Cigarette Smoking on Psychosicial Distress and Occupational Risks / 예방의학회지

The effects of cigarette smoking on the psychosocial distress, the absenteeism, the occupational injuries, and on the prevalence for the accidents were assessed in 795 male workers who had been employed since March 1994. The results show that the prevalence of current smokers were higher in young men, lower educational level, lower income, single men(unmarried or divorced), alcohol drinkers, and blue collar workers. In the bivariate analyses, the workers with the high job demand and low work control were more likely to smoke, although the relationship was not strong. Those who reported lower satisfaction on his job tended to smoke more. Mean scores of psychosocial well-being Index(PWI) were higher in current smokers than nonsmokers. For the hierarchical multiple regression analyses, interaction terms between cigarette smoking and job stressors(job demand and work control) were not significant. For smokers, the odds ratios for the occupational injuries, and the accidents were 1.40(95% confidence interval 0.77-2.57) and 1.96 (95% confidence interval 0.75-5.09), respectively. The mean absent day were 4.13 for smokers, 3.65 for nonsmokers, although the differences were not statistically significant. It seems that cigarette smoking had not caused any crucial effects on the psychosocial well-being status and the occupational risks. Some considerations for the further research on the relationship of cigarette smoking on the mental health status and the occupational risks were also discussed.

The Metabolism and Liver Toxicity of N, N-dimethylformamide in the Isolated Perfused Liver / 대한산업의학회지

N, N-dimethylformamide (DMF) is a solvent which is widely used in the industrial workplace. It causes the liver damages to the chronically exposed workers and is also well known as the harzadous material to generate occupational malignancies. DMF is mainly metabolized into N-hydroxymethyl-N-methylformamide (HMMF) by the microsomal cytochrome p-450. HMMF breaks down to NMF. However, the detailed mechanism of its toxicity are unknown. In this experiment, the metabolism and the toxicity of DMF was investigated using an isolated perfumed liver model. DMF (0, 10, 25mM) were added into recirculating perfusate of the isolated perfused rat liver. Samples were collected at 0, 30, 45, 60, 75, 90 minutes from inferior vena cava. The gas-chromatography was used to analyze the metabolite of DMF, The changes in the oxygen consumption rate by DMF were monitored during perfusion. The enzyme activity (AST, ALT, LDH) in the perfusate were treasured to find out whether DMF causers hepatotoxicity. As perfusion continued, DMF concentration in the perfusate decreased, and NMF 1.16mM was detected. The oxygen consumption rate increased both at 10mM and 25mM DMF concentration. However, when SKF 525A, a known inhibitor of cytochrome p-450, had been pretreated (300uM before DMF addition, the oxygen consumption rate was significantly inhibited, indicating that cytochrome p-450 system is responsible for the conversion to NMF. With DMF addition, the activity of AST, ALT, and LDH significantly increased time dependently and dose dependently. However, the pretreatment of perfused liver with SKF 525A shoved that the release of AST, ALT and LDH was inhibited. In summary, it is found that DMF is metabolized to NMF in liver, and that cytochrome p-450 mono-oxygenase is suggested to play a role in the biotransformation of NMF. The time course of BMF toxicity in relation to NMF formation is compatible with hypothesis that the hepatotoxicity of DMF is mediated via NMF. Further study combined with in vivo experiment through the toxicological approaches is expected.

Effect of Noise Exposure and Psychosocial Factors on Blood Pressure in Manufacturing Workers / 대한산업의학회지

This study was conducted to assess the effects of noise exposure and psychosocial factor on blood pressure in manufacturing workers. The study subjects are 414 workers (243 males, 171 females) employed at the noisy department. The mean age of low exposed group ( or =85dB) was 36.37+/-11.15 years. The difference in mean age wart not significant. The mean and distribution of working duration, smoking status, drinking status were not significantly different between two groups. The mean systolic blood pressure of the low exposed groups was 120.01+/-12.06 mmHg, and that of high exposed group wart 126.27+/-13.84 mmHg. The mean diastolic blood pressure of the low exposed and the high exposed group were 77.18+/-10.83 mmHg, and 83.46+/-11.22 mmHg respectively. These differences of blood pressure were statistically significant(p<0.05). The workers in noisy department have significantly less work environmental satisfaction, higher job demand, and higher social support. The mean values of psychosocial distress were higher in the workers of the noisy department, but the difference was not statistically significant. This study was to speculate whether the work environmental satisfaction and social supports modify the association between the noise exposure level and the blood pressure. The results showed that work environmental satisfaction could not modify the association between the blood pressure and the noise exposure. Social support at work did not modify the association. Furthermore, we evaluated the high job strain from a combination of high job demand and low job control at work. Compared to the low strain group, the olds ratio of the high job strain group for hypertension in diastolic blood pressure were statistically significant, but not in systolic blood pressure. Hierarchical multiple regression analysis was used to determine whether the independent variables contributed to explaining the blood pressure. After controlling for possible confounders, we found that the noise exposure level was a correlate of the diastolic blood pressure. But no association between the noise exposure level and the systolic blood pressure. No significant result was found for psychosocial factor.

Reliability and Validity on Measurement Instrument for Health Status Assessment in Occupational Workers / 예방의학회지

In order to test scaling assumption, and to assess the validity, reliability, and acceptability of the Short Form 36(SF-36) health survey questionnaire, we conducted a survey. Samples were 296 workers who had been employed in small sized companies. All scale passed for item internal consistency(100% sucess rate) and item discriminant validity(100% success rate). Reliability coefficients were ranged from a low of 0.51 to a high of 0.85. For 87.5% of the total workers, inconsistent responses were not observed. Only 3.0% of the total workers failed two or more checks. Factor analysis was performed using principal axis factor method and quartimax rotation. In this survey, the SF-36 retained available psychometric properties even when used in a generally healthy worker group. But further study with some consideration to develope health status measurement is expected ; first, the definition of health status should be rationalized. Second, the measurement of outcome is an important consideration in evaluations of quality of care. But ambiguities hinder understanding of this important topic. Third, internal consistency should be interpreted with caution as an indication reliability because it ignores potentially important sources of variation that can occur over time.