Organization and classification of work history data in industry‐wide studies: An application to the electric power industry

Abstract

Industry-based cohort studies require systems for organizing work history data. Although the ultimate goal may be to assess the hazards of specific exposures, classification of the job titles that comprise work histories serves an important descriptive purpose in itself and is often necessary before exposure data can be obtained. A system we have created for organizing jobs in a study of 135,000 workers at five electric power companies highlights conceptual and practical issues in managing work history data for epidemiological studies. Job characteristics including function, location, and authority were used to develop a system of 28 occupational categories. Comprehensibility, flexibility, and efficiency were important criteria in designing the system. Assessment of exposures was an implicit goal; the same categories will define job-exposure matrices for numerous agents. A combination of computer algorithms and expert judgment was used to assign individual job titles to the categories. This system facilitates examining the effects of various agents and controlling for confounding. The 28 categories can be collapsed and regrouped to analyze disease risks in relation to exposures to magnetic fields and other agents; even exposures not previously considered could be brought into the study with this generic system for organizing the electric power industry.

Assessment and grouping of occupational magnetic field exposure in five electric utility companies

“…Details of the sampling design and field methods of the magnetic field exposure survey have been described elsewhere (1 8), as have the classification and organization of the work history data from the cohort (19). A brief description of the survey is provided.…”

“…We conducted a large survey of occupational exposure to 60-Hz magnetic fields among randomly selected worlcers in 28 job categories in five electric utility companies (18)(19)(20). In relation to earlier assessments of occupational magnetic field exposure, this study has several design advantages that facilitate the examination of exposure variability.…”

Exposure to electromagnetic fields and suicide among electric utility workers: a nested case-control study

“…24,25 Exposure to EMFs was estimated by an assessment of exposure to magnetic fields, focusing on the time-weighted average, as described in detail elsewhere and briefly summarized here. 19,[26][27][28] Complete work histories were abstracted and computerized. To consolidate thousands of job titles at the 5 participating companies, 28 occupational categories were constructed based on work activities, responsibilities, and exposure potential 26 to define the rows of a job exposure matrix.…”

“…19,[26][27][28] Complete work histories were abstracted and computerized. To consolidate thousands of job titles at the 5 participating companies, 28 occupational categories were constructed based on work activities, responsibilities, and exposure potential 26 to define the rows of a job exposure matrix. Within the occupational categories, 1,060 distinct job titles were monitored.…”

Quantification of historical exposures in occupational cohort studies

“…An exception to this lack of information was a study of electrical workers (37), in which a detailed description was provided as to how the investigators developed their exposure groups. We recommend that the exposure estimation class used in studies be identified and documented in a similar manner.…”