ORGANIZATION AND CLASSIFICATION OF WORK HISTORY DATA IN INDUSTRY-WIDESTUDIES - AN APPLICATION TO THE ELECTRIC-POWER INDUSTRY

Industry-based cohort studies require systems for organizing work hist ory data. Although the ultimate goal may be to assess the hazards of s pecific exposures, classification of the job titles that comprise work histories serves an important descriptive purpose in itself and is of ten necessary before exposure data can be obtained. A system we have c reated for organizing jobs in a study of 135,000 workers at five elect ric power companies highlights conceptual and practical issues in mana ging work history data for epidemiological studies. Job characteristic s including function, location, and authority were used to develop a s ystem of 28 occupational categories. Comprehensibility, flexibility, a nd efficiency were important criteria in designing the system. Assessm ent 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 title s 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 exp osures to magnetic fields and other agents; even exposures not previou sly considered could be brought into the study with this generic syste m for organizing the electric power industry. (C) 1994 Wiley-Liss, Inc .