1685Screening for TB in Health Care Workers – QFT may not be the answer!

Background. Tuberculosis (TB) screening of healthcare workers (HCWs) is an important component of hospital infection control programs. Many institutions have replaced tuberculin skin tests (TSTs) with interferon-release gamma assays (IGRAs). Challenges of IGRA tests include daily fluctuations of IGRA values, serial testing variability, higher conversion rates of IGRAs than TSTs, and indeterminate IGRA results. In addition, reversions of positive QuantiFERON1 TB test (QFT) with low cut-off values (0.35 IU/mL to 1 IU/mL) to negative have also raised concerns. Additional data is needed for IGRA use in HCWs. An Employee Health algorithm was created prior to implementation of QFT testing at our institution. Methods. Retrospective review of all HCWs undergoing screening from January 2011 through December 2013 with QFTs was conducted. Employee health records including pre-employment TB screening questionnaire, and specific TB risk factors such as country of birth, history of BCG vaccination, prior TST and QFT results, chest radiograph, and occupational and social TB exposures were collected. Results. A total of 1267 employees were tested with QFT during the study period: 1154 (91%) were negative, 109 (8.6%) were positives and 4 (0.3%) were indeterminates. None of the HCWs with positive QFTs had chest radiograph findings consistent with active TB disease. The positive QFT values ranged from 0.35 to 15.29 IU/mL. Out of 109 positive QFT test results, 36 (33%) were within the low-positive QFT range and of those who had a repeat QFT within three months, all were negative. TB risk factors associated with a true-positive QFT were foreign born, travel to TB endemic country, direct patient care and known TB exposure. Conclusion. The risk of TB infection or conversion of QFT is low in persons without direct patient care. Low positive QFT cut-off values may indicate false positivity and the test should be repeated in 1 to 3 months especially in HCWs with no TB risk factors. Current healthcare employee TB testing program should be reviewed. Consideration for possible revision of policy for serial testing of only high risk HCWs with direct patient care will reduce health care expenses and unnecessary testing and treatment for low-risk HCWs. Disclosures. All authors: No reported disclosures.