Retrospective assessment of occupational exposure to whole-body vibration for a case-control study

Prevalence of Parkinson's disease in China: a multicenter population-based survey

OBJECTIVE

Few data are available on the current prevalence of Parkinson's disease in China. The aim of this study was to determine the prevalence of Parkinson's disease in Chinese individuals aged 65 years and older and to analyze associated risk factors.

METHODS

We performed a population-based cross-sectional survey with a multistage cluster sampling design. Residents aged 65 and over were drawn from 11 urban districts and 10 rural counties across China. Data were entered into spreadsheets, and imported and analyzed using Statistical Package SPSS 24.

RESULTS

We identified 151 patients with Parkinson's disease among 8124 residents aged 65 and over, including 75 men (49.67%) and 76 women (50.33%). The overall prevalence of PD in the study population was 1.86% (95% confidence interval [CI]: 1.6%-2.2%), and the standardized prevalence of PD was 1.60%. The crude prevalence in men (2.12%) was higher than in women (1.66%), and standardized prevalence in urban areas (1.98%) was higher than in rural areas (1.48%). Logistic regression analysis showed that independent risk factors for PD were older age, heavy metal or pesticide exposure (odds ratio [OR]=3.83; 95% CI: 2.021-7.256), urban residence (OR=1.307; 95% CI: 1.041-1.642), rapid eye movement sleep behavior disorder (OR=1.450; 95% CI: 1.021-2.059), and heart disease (OR=2.431; 95% CI: 1.481-4.990). Conclusion：The prevalence of Parkinson's disease in individuals aged 65 and older in China has not increased significantly in recent years. The prevalence of Parkinson's disease is higher in men than in women and higher in urban areas than in rural areas.

Association between Parkinson's Disease and Cigarette Smoking, Rural Living, Well-Water Consumption, Farming and Pesticide Use: Systematic Review and Meta-Analysis

Objective

Bradford Hill’s viewpoints were used to conduct a weight-of-the-evidence assessment of the association between Parkinson’s disease (PD) and rural living, farming and pesticide use. The results were compared with an assessment based upon meta-analysis. For comparison, we also evaluated the association between PD and cigarette smoking as a “positive control” because a strong inverse association has been described consistently in the literature.

Methods

PubMed was searched systematically to identify all published epidemiological studies that evaluated associations between Parkinson’s disease (PD) and cigarette smoking, rural living, well-water consumption, farming and the use of pesticides, herbicides, insecticides, fungicides or paraquat. Studies were categorized into two study quality groups (Tier 1 or Tier 2); data were abstracted and a forest plot of relative risks (RRs) was developed for each risk factor. In addition, when available, RRs were tabulated for more highly exposed individuals compared with the unexposed. Summary RRs for each risk factor were calculated by meta-analysis of Tier 1, Tier 2 and all studies combined, with sensitivity analyses stratified by other study characteristics. Indices of between-study heterogeneity and evidence of reporting bias were assessed. Bradford Hill’s viewpoints were used to determine if a causal relationship between PD and each risk factor was supported by the weight of the evidence.

Findings

There was a consistent inverse (negative) association between current cigarette smoking and PD risk. In contrast, associations between PD and rural living, well-water consumption, farming and the use of pesticides, herbicides, insecticides, fungicides or paraquat were less consistent when assessed quantitatively or qualitatively.

Conclusion

The weight of the evidence and meta-analysis support the conclusion that there is a causal relationship between PD risk and cigarette smoking, or some unknown factor correlated with cigarette smoking. There may be risk factors associated with rural living, farming, pesticide use or well-water consumption that are causally related to PD, but the studies to date have not identified such factors. To overcome the limitations of research in this area, future studies will have to better characterize the onset of PD and its relationship to rural living, farming and exposure to pesticides.

Prostate cancer and occupational exposure to whole-body vibration in a national population-based cohort study

BACKGROUND

Following preliminary evidence from observational studies, we test the potential relationship between whole-body vibration (WBV) and prostate cancer in a cohort study.

METHODS

WBV exposure was assigned based on occupation in 1991 and 1,107,700 participants were followed for incident prostate cancer until the end of 2003. Adjusted hazard rate ratios (HRs) were calculated using Cox proportional hazards modeling.

RESULTS

17,922 incident prostate cancer cases were observed. WBV-exposed men in Natural and Applied Sciences Occupations had a 37% elevated risk of prostate cancer (95% CI 1.09-1.72) and WBV-exposed men in Trades, Transport, and Equipment Operators Occupations had a 9% reduced risk (95% CI 0.86-0.97). Independent of WBV exposure, small but significant differences in risk were seen for several occupational categories.

CONCLUSIONS

We found no consistent relationship between WBV and prostate cancer. Further research could focus on other exposures or specific occupations in the studied categories to determine what may be contributing to the observed differences in prostate cancer risk.

Occupation and educational inequalities in laryngeal cancer: the use of a job index

BACKGROUND

Previous studies tried to assess the association between socioeconomic status and laryngeal cancer. Alcohol and tobacco consumption explain already a large part of the social inequalities. Occupational exposures might explain a part of the remaining but the components and pathways of the socioeconomic contribution have yet to be fully disentangled. The aim of this study was to evaluate the role of occupation using different occupational indices, differentiating between physical, psycho-social and toxic exposures and trying to summarize the occupational burden into one variable.

METHODS

A population-based case-control study conducted in Germany in 1998-2000 included 208 male cases and 702 controls. Information on occupational history, smoking, alcohol consumption and education was collected with face-to-face interviews. A recently developed job-classification index was used to account for the occupational burden. A sub-index focussed on jobs involving potentially carcinogenic agents (CAI) for the upper aero digestive tract.

RESULTS

When adjusted for smoking and alcohol consumption, higher odds ratios (ORs) were found for lower education. This OR decreased after further adjustment using the physical and psycho-social job indices (OR = 3.2, 95%-CI: 1.5-6.8), similar to the OR using the sub-index CAI (OR = 3.0, 95%-CI: 1.4-6.5).

CONCLUSIONS

The use of an easily applicable control variable, simply constructed on standard occupational job classifications, provides the possibility to differentiate between educational and occupational contributions. Such an index might indirectly reflect the effect of carcinogenic agents, which are not collected in many studies.

Occupational exposure to whole-body vibration and Parkinson's disease: results from a population-based case-control study

Mechanical stress producing head injury is associated with Parkinson's disease, suggesting that relations with other physical hazards such as whole-body vibration (WBV) should be tested. In this study, the authors evaluated the relation between occupational exposure to WBV and Parkinson's disease. A population-based case-control study with 403 cases and 405 controls was conducted in British Columbia, Canada, between 2001 and 2008. From detailed occupational histories and published measurements, metrics of occupational WBV exposure were constructed and tested for associations with Parkinson's disease using logistic regression and adjusting for age and sex first, and then also for smoking and history of head injury. While ever being occupationally exposed to WBV was inversely associated with Parkinson's disease (odds ratio = 0.67, 95% confidence interval: 0.48, 0.94), higher intensities had consistently elevated odds ratios, with a statistically significant effect being noted for intermediate intensities when exposures were restricted to the 10 years or more prior to diagnosis. Possible mechanisms of an inverse relation between low levels of WBV exposure and Parkinson's disease could include direct protective effects or correlation with other protective effects such as exercise. Higher intensities of WBV could result in micro-injury, leading to vascular or inflammatory pathology in susceptible neurons.