Jun Shigemi

Effects of perceived job stress on mental health. A longitudinal survey in a Japanese electronics company

We conducted a cohort study for 2 years to examine the causal relationship between perceived job stress and mental health. Questionnaire surveys, including a 30-item General Health Questionnaire (GHQ) and a questionnaire on perceived job stress were carried out every 6 months for 2 years. To clarify the causal relationship between job stress and mental health, we followed a group of workers who initially had a GHQ score ≥ 7. Out of 462 workers who were thought to be in a healthy mental state, 282 were successfully followed for 2 years. We considered subjects who developed unhealthy mental health states (GHQ score ≥ 8) as hazardous cases. To control potential confounding factors, proportional hazard analysis was done. The overall proportion hazardous cases detected in the development of an unhealthy mental health state over two years was 55.7%. Using Coxs proportional hazard model, workers who complained of perceived job stress had a greater hazard than those without job stress. In particular, the item ‘poor relationship with superior’ showed the largest adjusted hazard ratio [95% confidence interval (CI)] of 1.51 (1.06–2.15). The item ‘too much trouble at work’ also had a significant hazardous effect on mental health with an adjusted hazard ratio (95% CI) of 1.43 (1.00–2.04). Some specific items of perceived job stress could cause mental ill health in workers.

Does smoking cessation improve mental health

There is a possibility that cessation of smoking improves mental health, but there are no studies that have demonstrated this. A cohort study was performed for 1 year in 18 males who spontaneously stopped smoking (cessation group) and 173 who continued to smoke (smoking group). The mental health state was evaluated using the Japanese version of the 30‐item General Health Questionnaire (GHQ‐30) before the cessation of smoking and 6 months and 1 year after smoking cessation. Changes in the GHQ score were compared between the cessation and smoking groups. In order to control the effects of confounding factors, multiple regression analyses were performed using the GHQ score after 6 months and 1 year as dependent variables. The GHQ score in the cessation group significantly decreased 6 months and 1 year after smoking cessation (P < 0.04 and 0.01, respectively, by paired t‐test). In the smoking group, the GHQ score slightly decreased. Repeated measure analysis of variance revealed that the decrease in the GHQ score in the cessation group was significantly larger than in the smoking group. Multiple regression analysis revealed significant effects of smoking cessation on mental health after controlling for other confounding factors. It can be concluded that smoking cessation may improve mental health.

A case–control study of the relationships among silica exposure, gastric cancer, and esophageal cancer

BACKGROUND We examined the effect of silica exposure on gastric and esophageal cancer mortality using a cancer control series in a population setting. METHODS Cases and controls were restricted to male subjects and were drawn from death certificates in the Tobi area of Japan. A control group was selected from a series of deaths due to colon cancer, and cancers of other organs. The Japanese death certificate system is comprehensive because all deaths must be reported to the local office and death certificates are written by medical doctors. Age and smoking habits adjusted the Mantel-Haenszel odds ratios were estimated. RESULTS For gastric cancer, the age-, smoking-adjusted odds ratios were 1.22 (95% CI 0.74-2.01) for colon cancer and the other cancer control for silica exposure work, and 1. 36 (95% CI 0.76-2.43) for silicosis. For esophageal cancer, the age- and smoking-adjusted odds ratios were 1.53 (95% CI 0.59-3.96) for the cancer control for silica exposure, and 2.33 (95% CI 0.87-6.23) for silicosis, respectively. CONCLUSIONS The results suggest that gastric and esophageal cancer were related to silica exposure and silicosis in the study area, although they did not reach a statistically significant level because of the small sample size. The estimated odds ratios were higher for esophageal cancer and silicotic patients.

A case-control study of lung cancer in relation to silica exposure and silicosis in a rural area in Japan

PURPOSE In southeast Okayama Prefecture, Japan, there have been reports of a high prevalence of silicosis among refractory brick production workers. Recently, a high mortality rate of lung cancer among the local residents has been observed. Therefore, a population based case-control study was conducted concerning the relationship between silica, silicosis, and lung cancer using multiple cancer controls. METHODS Cases and controls were restricted to male subjects and information was obtained from death certificates from 1986 to 1993 in the area. Three categories of deceased control groups were selected: a series of deaths from liver cancer, colon cancer, and cancers of other organs, which was assumed not to be related to silica exposure. Age and smoking habits were adjusted by stratified analysis using the Mantel-Haenszel odds ratio estimates. Unconditional logistic regression analysis was also conducted to control potential confounding factors; such as age and smoking habits. RESULTS The age-, smoking-adjusted odds ratios were 1.94 (0.94-4.43) for the colon cancer control group, 2.13 (1.19-3.85) for the other cancer control group related to silica exposure, and 2.94 (1.30-8.90) and 2.69 (1.43-5.37) related to silicosis, respectively. The direct weighted average using the estimates for colon and the other cancer controls was 2.06 (1.29-3.29) for silica exposure, and 2.77 (1.60-4.77) for silicosis. Histological or cytological types of lung cancer cases were obtained from 64.1% of the subjects (118/184). As for the histologic type of lung cancer, small cell carcinoma was higher among those who had been silica-exposed workers than the unexposed lung cancer cases and the data from the general Japanese population. On chest x-ray findings, elevated lung cancer mortality compared with cancers other than lung cancer was demonstrated among patients without large opacities. CONCLUSIONS Silica exposure increased the lung cancer mortality in the area. A high lung cancer mortality rate in the area could be explained by silica exposure and silicosis prevalence in this area.

Stability of factor structure and correlation with perceived job stress in general health questionnaire: A three-wave survey over one year in Japanese workers

Stability of Factor Structure and Correlation with Perceived Job Stress in General Health Questionnaire: a Three‐wave Survey over One Year in Japanese Workers: Jun Shigemi, et al. Department of Hygiene and Preventive Medicine, Okayama University Medical School—A cross‐sectional study was conducted to examine psychological symptoms and job stress in Japanese workers. To assess the stability of the relationship between the parameters for perceived job stress and mental health, two additional surveys were carried out six months and one year later. The surveys included demographic questions, the General Health Questionnaire (GHQ), and questions relating to perceived job stress to measure the workers mental health and job stress. Factor analyses were conducted to clarify the factor structure of mental health. As for the GHQ, the 6 dominant factors were interpreted. These factors involved “Anxiety and depression”, “Severe depression”, “Lack of interpersonal network or social support”, “Poor social activity”, “Insomnia”, and “Lack of a positive attitude”. This structure was stable in the 2 follow up surveys. A multiple regression analysis was used to examine the relationship between extracted factors of the GHQ and job stress. The analysis showed that the factor “Anxiety and depression” had a significantly stable relationship with “Too much responsibility at work” and “Cannot keep up with new technology”.

Recovery from Mental Ill Health in an Occupational Setting : A Cohort Study in Japan

Recovery from Mental III Health in an Occupational Setting: A Cohort Study in Japan: Yoshio Mino, et al. Department of Hygiene and Preventive Medicine, Okayama University Medical School—Objectives: The purpose of this study is to clarify the degree of recovery from mental ill health in occupational settings and the nature of perceived job stress associated with recovery. Methods: A 1‐year cohort study was carried out in 287 of 763 workers who scored 8 or more on the General Health Questionnaire (GHQ‐30), and the proportion recovering during the year was compared according to the presence of individual perceived job stress items. To control confounding factors, multiple logistic analysis was used. Results: Recovery from mental ill health was observed in 48.7% after the first 6 months and in 66.1% after 1 year. During the first 6‐month period, no identified job stress item was associated with recovery. During the second 6‐month period, however, the odds ratio (95% confidence interval) between recovery and the absence of perceived job stress was 4.2 (1.3‐13.1) for “Too much responsibility”, even after controlling for sex, age, the degree of family life satisfaction, physical health state, and the initial GHQ score. Conclusion: Relief from excessive responsibility might promote recovery in mentally ill workers.