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Correspondence |

Relevance of Serial Interferon-γ Release Assays in Health-care WorkersSerial Interferon-γ Release Assays FREE TO VIEW

Deepak Aggarwal, MD; Phiza Aggarwal, MD; Prasanta Raghab Mohapatra, MD, FCCP
Author and Funding Information

From the Department of Pulmonary Medicine (Drs D. Aggarwal and Mohapatra), Government Medical College & Hospital; and Maharishi Markandeshwar Institute of Medical Sciences and Research (Dr P. Aggarwal).

Correspondence to: Deepak Aggarwal, MD, Department of Pulmonary Medicine, Block-D, Level-5, Government Medical College & Hospital, Sec-32, Chandigarh Pin-160030, India; e-mail: drdeepak@hotmail.com


Financial/nonfinancial disclosures: The authors have reported to CHEST that no potential conflicts of interest exist with any companies/organizations whose products or services may be dis­cussed in this article.

Reproduction of this article is prohibited without written permission from the American College of Chest Physicians. See online for more details.


Chest. 2012;142(6):1688. doi:10.1378/chest.12-1254
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To the Editor:

We read with interest the study by Park et al1 (see page 1461) in which they nicely evaluated serial interferon-γ (IFN-γ)-release assays (IGRAs) in the diagnosis of Mycobacterium tuberculosis (MTB) infection in health-care workers. Health-care workers, although at high risk for MTB infection, are generally less likely to develop active or severe TB. Considering unexplained fluctuations in IFN-γ levels, along with the high risk of conversions due to false positives in serial assays,2 conducting monthly IGRAs in health-care workers may give varied values that may not be of clinical use. Rather, it would be useful for the readers if the authors could provide follow-up data on the proportion of patients who received a diagnosis of MTB (IGRA-positive) who actually progressed to active TB. Retrospective evaluation of serial IFN-γ levels of such patients could provide a strong basis for formulating guidelines, incorporating their role in the management of latent and active TB.

It has been shown that circulating IFN-γ levels decrease with isoniazid and rifampicin chemoprophylaxis.3 However, the reasons for reversion of IGRAs in a subset of patients in the study was not discussed. It would be helpful if the authors could discuss the causes of such individual variations in IFN-γ response, as well as differentiate nonspecific variations from those associated with new or resolving infection.

References

Park JS, Lee JS, Kim MY, et al. Monthly follow-ups of interferon-γ release assays among health-care workers in contact with patients with TB. Chest. 2012;142(6):1461-1468.
 
Mazurek GH, Jereb J, Vernon A, LoBue P, Goldberg S, Castro K; IGRA Expert Committee; Centers for Disease Control and Prevention (CDC). Updated guidelines for using Interferon Gamma Release Assays to detectMycobacterium tuberculosisinfection-United States, 2010. MMWR Recomm Rep. 2010;59(RR-5):1-25. [PubMed]
 
Lee SW, Lee SH, Yim JJ. Serial interferon-gamma release assays after chemoprophylaxis in a tuberculosis outbreak cohort. Infection. 2012;40(4):431-435. [CrossRef] [PubMed]
 

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References

Park JS, Lee JS, Kim MY, et al. Monthly follow-ups of interferon-γ release assays among health-care workers in contact with patients with TB. Chest. 2012;142(6):1461-1468.
 
Mazurek GH, Jereb J, Vernon A, LoBue P, Goldberg S, Castro K; IGRA Expert Committee; Centers for Disease Control and Prevention (CDC). Updated guidelines for using Interferon Gamma Release Assays to detectMycobacterium tuberculosisinfection-United States, 2010. MMWR Recomm Rep. 2010;59(RR-5):1-25. [PubMed]
 
Lee SW, Lee SH, Yim JJ. Serial interferon-gamma release assays after chemoprophylaxis in a tuberculosis outbreak cohort. Infection. 2012;40(4):431-435. [CrossRef] [PubMed]
 
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