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Fatiguing illness among employees in three large state office buildings, California 1993: was there an outbreak?

Shefer A, Dobbins JG, Fukuda K, Steele L, Koo D, Nisenbaum R, Rutherford GW.
Fatiguing illness among employees in three large state office buildings, California 1993: was there an outbreak?
Journal of Psychiatric Research, vol. 31, pages 31-43, 1997.

Summary

In response to a request from the state of California, CDC investigated a potential cluster of fatiguing illness in northern California in the summer of 1993. Self-administered questionnaires designed to provide evidence for CFS-like illness were provided 2000 employees in two office buildings in which a possible cluster of fatiguing illness had been identified. An additional 2000 questionnaires were provided to employees in a third (control) office building that appeared to be uninvolved in the cluster. 82% of the questionnaires (representing 3312 workers) were completed and returned. The number of employees with fatiguing illness in the two test buildings was not significantly higher than that for the control building. Nonetheless, a substantial number of employees experienced fatiguing illness in this study population as a whole.

Abstract

The objective was to determine if a cluster of chronic fatigue syndrome (CFS)-like illness had occurred among employees in two large state office buildings in northern California, and to identify risk factors for and features of fatiguing illness in this population.

Design: Case-control study. Population and Setting: Over 3300 current employees in two state office buildings and employees in a comparable "control" building. Information was collected on demographic and occupational variables, the occurrence of fatiguing illness for at least 1 month in the previous year, and the presence of 36 symptoms.

Main Results: A total of 3,312 (82%) of 4,035 employees returned questionnaires. Overall, 618 (18.7%) persons reported fatigue lasting at least 1 month; including 382 (11.5%) with fatigue of at least 6 months' duration and 75 (2.3%) with symptoms compatible with a CFS-like illness. Independent risk factors for fatigue lasting 1 month or longer were found to be Native American ethnicity (OR 2.4, CI 1.1,5.3), Hispanic ethnicity (OR 1.7, CI 1.3,2.3), female sex (OR 1.5, CI 1.2,1.9), gross household incomes of less than $50,000 (OR 1.3, CI 1.1,1.6), and less than a college education (OR 1.3, CI 1.1,1.6). Similar risks were observed for persons who reported fatigue lasting 6 months or longer. Female sex (OR 3.2, CI 1.7, 6.4) was the only independent risk factor found for those persons classified as having a CFS-like illness. Case prevalence rates for all three categories of fatigue, as determined by multivariate analysis, were not significantly different among buildings.

Despite finding a substantial number of employees with fatiguing illness in the two state office buildings, the prevalence was not significantly different than that for a comparable control building. Previously unidentified risk factors for fatigue of at least 1 month and at least 6 months identified in this population included Hispanic ethnicity, not having completed college, and income below $50,000.

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