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Epidemiologic research that uses administrative records (rather than registries or clinical surveys) to identify cases for study has been increasingly restricted because of concerns about privacy, making unbiased population-based research less practicable. In their article, Nattinger et al. (Am J Epidemiol. 2010;172(6):637–644) present a method for using administrative data to contact participants that has been well received. However, the methods employed for calculating and reporting response rates require further consideration, particularly the classification of untraceable cases as ineligible. Depending on whether response rates are used to evaluate the potential for bias to influence study results or to evaluate the acceptability of the method of contact, different fractions may be considered. To improve the future study of epidemiologic research methods, a consensus on the calculation and reporting of study response rates should be sought.

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. Language: en