A university hospital's 10-year experience with tuberculin testing: value of the 2-step tuberculin skin test.

Background: The usefulness of the 2-step tuberculin skin test as a tool for monitoring tuberculosis exposure among health care workers is controversial.
Objectives: We aimed to determine the cost-effectiveness and influence of initiation of a preemployment, 2-step tuberculin skin-testing program on the annual tuberculin skin conversion rate among a university hospital's health care workers.
Methods: The tuberculin skin test conversion rates among the recipients of 31,729 tuberculin skin tests over 10 years were retrospectively analyzed. Data from the first 6 years of this study were generated when a single preemployment tuberculin skin test was utilized. Data from the last 4 years were gathered after the advent of a preemployment 2-step program. A cost analysis of the 2-step tuberculin skin test process was performed to determine the annual cost of this program.
Results: Relative risk of a conversion was 8.43 times less during the 2-step period when compared with the years when a single tuberculin skin test was given at the start of employment (P < .001). A cost analysis showed that the annual added cost of the 2-step program was approximately 9,565 US dollars.
Conclusion: A greater than 8-fold reduction in the number of annual tuberculin skin test conversion coincided with, but could not be attributed solely to, the initiation of a 2-step program in our hospital. The Infection Control Committee concluded that the 2-step testing program is essential to achieve the hospital's goal of a 0% annual tuberculin skin test conversion rate and that the annual cost is justified.