Data pooling in occupational studies
Article Abstract:
The identification and characterization of environmental and occupational risks frequently require studies of large populations and long time intervals. This is especially true in cases of cancers, where long induction times are the rule rather than the exception. In order to amass a sufficient number of cases, it may be necessary to assemble the results of multiple tests and analyze the data collectively. Meta-analysis is a method that weights the data obtained from similar studies, to increase the number of cases and permit more valid qualitative or quantitative risk assessments to be made. Meta-analysis is relied upon by the Environmental Protective Agency and other national and international agencies. Another method involves pooling the data collected from many, simultaneously conducted studies. This approach can be built into the design of the concurrent studies, but is most commonly initiated at the end of the studies. As an alternative, previously published data can be aggregated and analyzed. In order for these pooling efforts to be usable, the demographics of the subject groups, their employment intervals, and exposure and outcome intervals must be known. The repeat analysis of segments of the pooled data set can be valuable, in that errors of omission and commission can be detected the second time around. One of the more significant difficulties with pooled data, however, is the potential loss or attenuation of the results from local sites. Pooling data has yet to meet with wide acceptance for these and other reasons. (Consumer Summary produced by Reliance Medical Information, Inc.)
Publication Name: Journal of Occupational Medicine
Subject: Health care industry
ISSN: 0096-1736
Year: 1991
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Importance of the study protocol in epidemiologic research
Article Abstract:
Adequacy of the protocol of any scientific inquiry is the foundation of successful research. In preparing the protocol, the underlying assumptions should be thoroughly clarified, the design should be prepared so that valid conclusions can be drawn, and the study should be conducted in such a manner as to produce credible data and analysis. In the area of occupational and environmental health, these matters are not easily reconciled, because most studies are observational and not experimental. The experimental approach employs techniques that are not immediately available in the observational approach. The proper selection of controls that closely resemble the exposed group, in terms of confounding variables and other nonmeasured factors, may approximate the randomization of participants that is employed in experimental studies. Restriction, in experimental studies, is used to selectively exclude participation. In observational studies, restriction may also be employed to limit participation, and can be used to narrow the limits of exposure and the assessment of the health outcomes. The use of double blind studies, in which neither the observer nor the participant is aware of exposure or treatment, is not readily applicable to observational studies. In general, a peer-reviewed protocol more readily assures the development of an investigation with integrity and credible results. (Consumer Summary produced by Reliance Medical Information, Inc.)
Publication Name: Journal of Occupational Medicine
Subject: Health care industry
ISSN: 0096-1736
Year: 1991
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An update of mortality due to brain neoplasms and other causes among employees of a petrochemical facility
Article Abstract:
A previous study of mortality among workers in a petrochemical plant between 1941 and 1983 was updated to include the next six years. Previous data showed an excessive number of brain tumors (BT) among hourly workers, but revealed no identifiable work-related factors. The update focused on male employees who worked one day or more, and was modified by the inclusion of nonwhites in the study. Production job assignments were categorized on the basis of the chemical product made, and agreed with the original areas defined by the National Institute of Occupational Safety and Health (NIOSH). Maintenance positions were divided into one of eight craft groups. The additional years of observation and the addition of the nonwhite data increased the total number of deaths in the study population to 1,350 persons. Brain tumor rates were still somewhat higher than expected among hourly workers, but this finding continued to be unexplained by production area work assignments. Mortality for all cancers was below the expected rate, and below the rate in the United States' general population. Vinyl chloride workers experienced greater than expected liver cancer rates. Other observed and expected death (O-E) data updates and comparative results are presented. (Consumer Summary produced by Reliance Medical Information, Inc.)
Publication Name: Journal of Occupational Medicine
Subject: Health care industry
ISSN: 0096-1736
Year: 1991
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