Retrospective cohort study of the risk of obesity among shift workers: findings from the Industry-based Shift Workers' Health study, Japan.

OBJECTIVES: The authors investigated the effect of shift working on the risk of obesity using data from the Industry-based Shift Workers' Health (IbSH) study, a retrospective cohort study based on a health care database system belonging to a manufacturing corporation in Japan. METHODS: The study database contains data on annual health check-ups and work schedules for every worker in the corporation in Japan since 1981. Study subjects consisted of 9912 male employees (8892 daytime workers and 920 rotating three-shift workers; mean age at first check-up was 23.7 years) whose work schedules were consistent during the follow-up period. Obesity was defined as a body mass index ≥ 25.0. RESULTS: 3319 cases of obesity were recorded over the 27.5 years of retrospective follow-up. Kaplan-Meier survival analysis visually demonstrated an increased risk of obesity among shift workers. The risk becomes particularly obvious after 10 years of follow-up. Cox proportional-hazards model analysis revealed a significantly increased risk among shift workers (RR 1.14, 95% CI 1.01 to 1.28). CONCLUSION: The risk of obesity among male shift workers was visually and statistically demonstrated.

Diagnosis of fulminant pneumonia caused by Legionella pneumophila serogroup 8 with the sequence analysis of the 16S rRNA gene.

Pneumonia is the fourth leading cause of death in Japan. Accurate and rapid detection of the causative pathogen(s) is necessary and important for appropriate antimicrobial treatment, especially in patients with rapidly progressive pneumonia or immunocompromised patients. Conventional methods, such as cultivations, detection of urinary antigens or PCR amplification of specific genes, inevitably require the precise presumption of potential pathogens in each case, and pneumonia caused by unanticipated microorganisms might lead to inadequate antimicrobial treatments and unfortunate consequences. We herein report an immunocompromised female patient (69 years old) with fulminant pneumonia caused by Legionella (L.) pneumophila serogroup 8. Ordinary cultivation methods and urinary antigen detection failed to identify the causative organisms. Accordingly, DNA was extracted from the bronchoalveolar lavage fluid and used for the PCR-based cloning of the bacterial 16S rRNA gene. Sequencing analysis of the isolated clones revealed the predominance of L. pneumophila. Based on this information, the patient received an appropriate and successful antimicrobial treatment. In addition, L. pneumophila serogroup 8 was identified with culturing the bronchoalveolar lavage fluid and serotyping with L. pneumophila antisera. The 16S rRNA gene sequencing analysis can reveal the potential pathogens without any presumption about the organism, and can evaluate the kinds and ratio of bacterial species in each specimen. In conclusion, this cultivation-independent method is a potential diagnostic modality for pneumonia, especially in patients with rapidly progressive pneumonia or those who are immunocompromised.

Industry-based retrospective cohort study of the risk of prostate cancer among rotating-shift workers.

OBJECTIVES: The risk of prostate cancer among shift workers was examined in the present industry-based retrospective cohort study. METHODS: The study was established based on a health-care database from a Japanese manufacturing corporation. Work schedules of 4995 male workers (mean age = 55.5 years) were followed up retrospectively; mean follow-up period = 25.0 years. Of the subjects, 4168 had previously undertaken only daytime work (daytime workers), whereas 827 had undertaken rotating three-shift work for >80% of their career (shift workers). All subjects had undergone prostate-specific antigen (PSA) testing. Prostate cancer incidence data were obtained from the health insurance records of 13 daytime and four shift workers. Multivariate logistic regression was used to estimate the relative risk of prostate cancer for the two groups with adjustments for age, body mass index, alcohol intake, smoking, exercise and marital status. RESULTS: Compared with daytime workers, shift workers showed a non-significant increase in the risk of prostate cancer (odds ratio = 1.79; 95% confidence interval = 0.57, 5.68; P-value = 0.32). CONCLUSIONS: Some increase in the risk of prostate cancer for shift workers was observed, although the result was not statistically significant as a result of the small number of cases. To identify the prostate cancer risk among shift workers, longer-term follow up, including the period after retirement, is required.

[A case of localized malignant pleural mesothelioma].

A 74-year-old man was referred to our hospital for examination of an abnormal chest shadow. A chest computed tomography (CT) scan revealed a 5-cm mass attached to the pleura involving the right upper lobe, and a nodule in the right middle lobe. Transbronchial lung biopsy was performed twice, but no definitive diagnosis was achieved. 18-fluorodeoxyglucose positron emission tomography showed abnormal uptake in the chest lesion. Chemotherapy was initiated for advanced-stage lung cancer, but was not effective. Histopathologic and immunohistochemical examinations after CT-guided needle biopsy revealed malignant mesothelioma. The tumor cells were positive for calretinin and thrombomodulin, and negative for CEA, TTF-1, and SP-A. There was local tumor invasion and metastasis in the lung and brain, without diffuse pleural spread. This is a rare and important case of localized malignant mesothelioma pathologically confirmed by biopsy.

[A case of rheumatoid arthritis with pneumothorax due to subpleural pulmonary rheumatoid nodules].

Pneumothorax secondary to nodular rheumatoid lung disease is a rare complication of rheumatoid arthritis. Here we report a case of rheumatoid arthritis with pneumothorax due to subpleural pulmonary rheumatoid nodule. A 74-year-old woman with a 14-year history of rheumatoid arthritis has admitted to our hospital due to dyspnea and right chest discomfort, and her chest X-ray film and computed tomography revealed right pneumothorax. Her chest X-ray and computed tomography findings before the onset of pneumothorax had demonstrated multiple subpleural cavitary nodules in both lungs. She had taken antifungal agents under a diagnosis of pulmonary fungal infection for a year without any change of her chest radiological findings. After incomplete reexpansion with sustained air leakage by right chest tube drainage, video-assisted thoracic surgery was performed. The pulmonary cavitary nodules of her right middle and lower lobes were with successfully excised. The histopathology of excised subpleural lung nodules showed typical features of rheumatoid nodules, and the cavitation of the rheumatoid nodule in right S5 had fistula formation to the pleural space, and thus was thought to have caused the pneumothorax.

[Early case of idiopathic pulmonary alveolar proteinosis positive for serum anti-GM-CSF antibody].

An asymptomatic 56-year-old woman who had never smoked and had been healthy was admitted to our hospital because of abnormal shadows on a chest X-ray film taken on a medical check-up. Chest CT showed ground-glass opacities in the right upper lung field. No abnormality on chest X-ray had been pointed out on any annual medical check up until then. As bronchofiberscopy (BAL and TBLB) could not reveal any diagnostic information, VATS biopsy was performed. Histological findings showed that alveolar spaces were filled with PAS-positive granular materials, and fused membrane structures and amorphous material were demonstrated by electron microscopy. Anti-GM-CSF antibody of serum was also positive (7.908 microg/ml). Based on these findings, we decided this was an early case of idiopathic pulmonary alveolar proteinosis.

Evaluation and simplification of the occupational slip, trip and fall risk-assessment test.

OBJECTIVE: The purpose of this investigation is to evaluate the efficacy of the occupational slip, trip and fall (STF) risk assessment test developed by the Japan Industrial Safety and Health Association (JISHA). We further intended to simplify the test to improve efficiency. METHODS: A previous cohort study was performed using 540 employees aged ≥50 years who took the JISHA's STF risk assessment test. We conducted multivariate analysis using these previous results as baseline values and answers to questionnaire items or score on physical fitness tests as variables. The screening efficiency of each model was evaluated based on the obtained receiver operating characteristic (ROC) curve. RESULTS: The area under the ROC obtained in multivariate analysis was 0.79 when using all items. Six of the 25 questionnaire items were selected for stepwise analysis, giving an area under the ROC curve of 0.77. CONCLUSION: Based on the results of follow-up performed one year after the initial examination, we successfully determined the usefulness of the STF risk assessment test. Administering a questionnaire alone is sufficient for screening subjects at risk of STF during the subsequent one-year period.

A cross-sectional study of workplace social capital and blood pressure: a multilevel analysis at Japanese manufacturing companies.

OBJECTIVES: We examined the contextual effect of workplace social capital on systolic blood pressure (SBP). DESIGN: Cross-sectional. SETTING: A conglomerate from 58 workplaces in Japan. PARTICIPANTS: Of the 5844 workers at a Japanese conglomerate from 58 workplaces, 5368 were recruited. Individuals who received drugs for hypertension (n=531) and who lacked information on any variable (n=167) were excluded from the analyses, leaving 4735 individuals (3281 men and 1454 women) for inclusion. PRIMARY AND SECONDARY OUTCOME MEASURES: Systolic blood pressure. RESULTS: The contextual effect of workplace social capital on SBP was examined using a multilevel regression analysis with a random intercept. Coworker support had a contextual effect at the workplace level (coefficient=-1.97, p=0.043), while a lack of trust for coworkers (coefficient=0.27, p=0.039) and lack of helpfulness from coworkers were associated with SBP (coefficient=0.28, p=0.002). CONCLUSIONS: The present study suggested that social capital at the workplace level has beneficial effects on SBP.

An industry-based cohort study of the association between weight gain and hypertension risk among rotating shift workers.

OBJECTIVES: We investigated whether the association between shift work and hypertension is independent of weight gain. METHODS: Subjects were 10,173 male employees (9209 daytime workers, 964 three-shift workers; mean follow-up period: 12.7 years). Hypertension was defined as systolic blood pressure 140 mm Hg or more or diastolic blood pressure 90 mm Hg or more. The risk of developing hypertension among shift workers was estimated using a Cox proportional hazards model with adjustment for several factors. RESULTS: Analysis revealed that "shift work" (hazard ratio [HR]: 1.85; 95% confidence interval [CI]: 1.68, 2.03), "baseline body mass index" (HR: 1.13; 95% CI: 1.12, 1.15), and "increase in body mass index during follow-up" (HR: 1.15; 95% CI: 1.13, 1.17) were significant independent risk factors for hypertension. CONCLUSIONS: Shift work is a significant risk factor for hypertension that is independent of both starting weight and weight gained over years of work.

Retrospective cohort study of the risk of impaired glucose tolerance among shift workers.

OBJECTIVES: The aim of this study was to investigate the effect of shift working on the risk of developing impaired glucose tolerance (IGT). METHODS: This study comprised 6413 male employees (5608 daytime workers, 512 3-shift workers and 293 2-shift workers) whose work schedules remained constant during the follow-up period (mean follow-up period 9.9 years). IGT was defined as Hemoglobin A1c ≥ 5.9%. The Cox proportional hazards model was used to estimate the risk of developing IGT, after making adjustments for age, smoking, alcohol consumption, leisure-time physical activity, body mass index (BMI) and Hemoglobin A1c (HbA1c) at baseline. Analysis was additionally performed for a sub-cohort of 1625 workers with BMI of 20.0-25.0 kg/m² that did not change by >2.0 kg/m² during the follow up period. RESULTS: The risk of developing IGT was significantly elevated among both 3-shift workers [hazard ratio (HR) 1.78, 95% confidence interval (95% CI) 1.49- 2.14] and 2-shift workers (HR 2.62, 95% CI 2.17-3.17). Significant elevations of the risk were still observed at the additional analysis on the sub-cohort (3-shift work: HR 3.55, 95% CI 2.02-6.25; 2-shift work: HR 4.86, 95% CI 2.62-9.01). CONCLUSIONS: Both 2- and 3-shift workers were associated with a high risk factor of developing IGT compared to day workers. Moreover, 2-shift workers had a higher risk than 3-shift workers. The risk was observed even among workers whose body mass remained within the normal range.