{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,8,28]],"date-time":"2026-08-28T18:32:46Z","timestamp":1787941966278,"version":"build-2784847793"},"reference-count":31,"publisher":"Oxford University Press (OUP)","issue":"8","license":[{"start":{"date-parts":[[2013,10,1]],"date-time":"2013-10-01T00:00:00Z","timestamp":1380585600000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/academic.oup.com\/pages\/standard-publication-reuse-rights"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":[],"published-print":{"date-parts":[[2013,10,15]]},"abstract":"<jats:title>Abstract<\/jats:title>\n                  <jats:sec>\n                    <jats:title>Rationale<\/jats:title>\n                    <jats:p>North American occupational health programs that switched from the tuberculin skin test (TST) to IFN-\u03b3 release assays for latent tuberculosis screening are reporting challenges with interpretation of serial testing results in healthcare workers (HCWs). However, limited data exist on the reproducibility of serial IFN-\u03b3 release assay results in low-risk HCWs.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Objectives<\/jats:title>\n                    <jats:p>To evaluate the short-term reproducibility of QuantiFERON-TB Gold In-Tube (QFT) in a large cohort of HCWs and to define a QFT cutoff yielding a conversion rate equivalent to historical TST rates.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Methods<\/jats:title>\n                    <jats:p>We retrospectively evaluated the QFT results from HCWs with two or more QFT tests performed between June 2008 and July 2010 at an academic institution. Outcome measures were proportions of reproducibility, quantitative results, and conversion rates with alternate QFT cutoffs.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Measurements and Main Results<\/jats:title>\n                    <jats:p>A total of 9,153 HCWs with two or more QFT tests were included in the analysis. Of 8,227 individuals with a negative result, 4.4% (n = 361) converted their QFT result over 2 years. A total of 261 (72.3%) of the HCWs with conversions underwent repeat short-term testing after the first positive result with 64.8% reverting (n = 169). An IFN-\u03b3 cutoff of 5.3 IU\/ml or higher (manufacturer\u2019s cutoff is \u22650.35 IU\/ml) yielded a conversion rate of 0.4%, equal to our institution\u2019s historical TST conversion rate.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Conclusions<\/jats:title>\n                    <jats:p>The manufacturer\u2019s definition of QFT conversion results in an inflated conversion rate that is incompatible with our low-risk setting. A significantly higher QFT cutoff value is needed to match the historical TST conversion rate. Nonreproducible conversions in most converters suggested false-positive results.<\/jats:p>\n                  <\/jats:sec>","DOI":"10.1164\/rccm.201305-0831oc","type":"journal-article","created":{"date-parts":[[2013,8,26]],"date-time":"2013-08-26T16:35:05Z","timestamp":1377534905000},"page":"1005-1010","source":"Crossref","is-referenced-by-count":91,"title":["Challenges with QuantiFERON-TB Gold Assay for Large-Scale, Routine Screening of U.S. Healthcare Workers"],"prefix":"10.1093","volume":"188","author":[{"given":"Madeline L.","family":"Slater","sequence":"first","affiliation":[{"name":"Department of Medicine and"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Gary","family":"Welland","sequence":"additional","affiliation":[{"name":"Infection Control and Epidemiology, Stanford University Medical Center, Stanford, 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