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Equipment Watch: Respirators and TB protection

Outbreaks of multidrug resistant tuberculosis led the Centre for Disease Control and Prevention in the US to propose using high-efficiency particulate air filters (HEPA respirators) in isolation procedures against tuberculosis. Each HEPA respirator costs 10 times more than respirators currently used.

The University of Virginia Health Sciences have conducted a cost-effectiveness study. They used data from the University of Virginia Hospital on exposure to patients with TB and rates at which the purified-protein-derivative (PPD) skin tests became positive in hospital workers.

In 1992 eleven patients with documented TB were admitted. Eight of 3852 workers (0.2%) had PPD tests that became positive. Five conversions were due to the booster phenomenon, one to unprotected exposure to a patient not yet in isolation, and two more in workers who had never entered a tuberculosis isolation room.

HEPA respirators used for one year would not prevent a single conversion of the PPD test. If one conversion were prevented a year, it would take 41 years to prevent one case of occupationally acquired TB at a cost of $1.3 - $18.5 million. Given the effectiveness of currently recommended procedures to prevent transmission of tuberculosis, HEPA respirators would offer negligible extra protection at great cost.

  1. KA Adal, AA Anglim, CL Palumbo et al. The use of high-efficiency particulate air-filter respirators to protect hospital workers from tuberculosis. New England Journal of Medicine 1994 331: 169-73.

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