Implementation of an interferon-gamma release assay to screen for tuberculosis in refugees and immigrants

Despite increased use and accuracy of interferon-gamma release assays to detect latent tuberculosis infection (LTBI) in foreign-born arrivals in the United States, risk characteristics associated with positive results are not well characterized. We conducted a retrospective record review of 541 refugees and immigrants screened for LTBI with QuantiFERON(®)-TB Gold In-Tube (QFT-IT) at the Spokane Public Health Clinic from January 2, 2008, through June 5, 2009. Overall, 24 % of the arrivals had a positive QFT-IT, with the greatest frequency of positive results occurring in arrivals from Liberia (100 %) and Bhutan (39 %). More than the expected number of Burmese had indeterminate QFT-IT results. A positive QFT-IT was associated with age, race, ethnicity, and extent of TB burden in the country of origin. QFT-IT is useful to screen for LTBI in foreign-born arrivals, particularly middle-aged adults from high-burden countries. However, the QFT-IT may not yield meaningful results in groups with significant immunocompromise.