Preemployment screening for tuberculosis in a large health care setting: comparison of the tuberculin skin test and a whole-blood interferon-γ release assay.

Objective: Determine the performance of an interferon-γ release assay in a health care occupational surveillance program.

Methods: From January 11, 2005, through January 31, 2006, all new employees (n = 652) undergoing standard, preemployment evaluation at Mayo Clinic, Rochester, Minnesota were evaluated for tuberculosis using a standard process of symptom screening combined with tuberculin skin test (TST) and QuantiFERON-TB Gold test (QFT-G).

Results: Comparing the results of QFT-G directly to TST, QFT-G showed an overall agreement of 92.5%.

Conclusions: False-positive TST were the most significant issue affecting agreement, and in a low-tuberculosis prevalence population, the need for an effective strategy offering low false-positive results may be best met by combining the TST with QFT-G.