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- Title
Late boosting phenomenon in TST conversion among health care workers.
- Authors
Farah, W. H.; Breeher, L. E.; Newcomb, R. D.; Murad, M. H.; Vaughn, A. I. S.; Hagen, P. T.; Molella, R. G.
- Abstract
Background Available information is insufficient to guide determination of whether tuberculin skin test (TST) conversions of health care workers (HCWs) within 2 years of two-step testing are related to occupational exposures or to other causes, including late boosting. Aims To describe the epidemiologic factors of TST conversion in HCWs, comparing early TST conversion (≤2 years after two-step testing) with late conversion to possibly distinguish late boosting phenomenon from occupational TST conversion. Methods Retrospective analysis of a database of TSTs of HCWs from 1 January 1998, through 31 May 2014, in the United States Midwest. Results In total, 40 142 HCWs had 197 932 tests over the 16 years, with 123 conversions (conversion rate: 0.3%; 95% CI 0.3-0.4%). Among 61 HCWs with a negative two-step TST, 30 (49%) were found to have early TST conversion within 2 years; 31 (51%) had late conversion, with likely occupational exposure but no identifiable community risks. Persons with early conversion were more likely to be born outside the USA (89% versus 57%; P < 0.05), had a higher rate of prior bacille Calmette-Guérin (BCG) vaccination (89% versus 52%; P < 0.05) and had no identifiable risk factors for conversion (63% versus 58%; P < 0.05). Conclusions Early conversions among HCWs after negative two-step TST are associated with various nonoccupational factors, including international birth and BCG vaccination history. Therefore, conversion is not a reliable indicator of recent tuberculosis contact in this population, and two-step TST is insufficient to discount a delayed boosting response for HCWs.
- Subjects
MEDICAL personnel; MEDICAL care; TUBERCULIN test; INDUSTRIAL hygiene; OCCUPATIONAL diseases
- Publication
Occupational Medicine, 2017, Vol 67, Issue 6, p484
- ISSN
0962-7480
- Publication type
Article
- DOI
10.1093/occmed/kqx102