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Tuberculosis in the Workplace
sions among hospital workers exposed on the HIV ward in late 1990 were recorded in early 1991 (Wenger et al. 1995). Also, tuberculosis control measures (e.g., stricter isolation protocols) were still being implemented on the HIV ward in 1991. The committee questions the appropriateness of using outbreak-affected data as a basis for the high-end estimates of the effects of the proposed regulations on occupationally acquired infections.
Based on its estimating procedures and assumptions, OSHA concluded that implementation of the proposed rule would prevent each year between 1,477 and 1,744 cases of active tuberculosis among workers covered by the rule (p. 54219, Table VII-3). CDC data raise some questions about the plausibility of these estimates. In its surveillance report for 1999, CDC lists a total of 551 cases of tuberculosis among health care workers and 16 cases among correctional facility workers (CDC, 2000b).6 This figure is less than two-thirds the number of cases that OSHA predicted would be prevented yearly by the implementation of its proposed rule. Moreover, of the reported cases of active disease reported, some proportion will have been the result of community rather than workplace exposure.
Although the figure is widely cited and used (including by the CDC), the committee also questions OSHA’s estimate that 10 percent of workers infected with M. tuberculosis would progress to active disease over their lifetimes. Two reviewers of the initial OSHA risk assessment (George Comstock and Bahjat Qaqish) questioned whether this estimate was too high, although a third reviewer (Neil Graham) noted that it was widely accepted (see 62 FR 201 at 54198). In this report’s background paper on the occupational risk of tuberculosis (Appendix C), the author (Thomas M.Daniel) likewise questions the 10 percent figure based on data analyses indicating that the rate of progression is probably half that figure or less, especially in populations more likely than average to be treated for latent infection. Most health care workers constitute such a population, although home health workers, workers in homeless shelters, and certain other groups covered by the proposed rule may have less access to health insurance and health care. The committee recognizes that the rate of compliance with treatment for both latent infection and active disease is often
Health care and correctional workers account for about 95 percent of those covered by the proposed rule. The CDC data are based on reported occupation within the past 24 months (CDC, 2000b). Most of the progression from infection to active tuberculosis occurs within the first two years following infection. CDC first began collecting occupational data in 1993, but the initial reports are considered less reliable than subsequent ones. In recent years, approximately 500 to 600 cases of tuberculosis among health care workers have been reported yearly.