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-gamma 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.