Open Access Highly Accessed Research article

Performance of whole-blood interferon-gamma release assay in patients admitted to the emergency department with pulmonary infiltrates

Yoon Jee Lee1, Jaehee Lee1, Yi Young Kim1, Dong Il Won2, Seung Ick Cha1, Jae Yong Park1, Tae Hoon Jung1 and Chang Ho Kim1*

  • * Corresponding author: Chang H Kim kimch@knu.ac.kr

  • † Equal contributors

Author Affiliations

1 Department of Internal Medicine, Kyungpook National University, School of Medicine, Daegu, Republic of Korea

2 Clinical Pathology, Kyungpook National University, School of Medicine, Daegu, Republic of Korea

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BMC Infectious Diseases 2011, 11:107  doi:10.1186/1471-2334-11-107

Published: 24 April 2011

Abstract

Background

This study was conducted to evaluate the performance of a whole-blood interferon-gamma release assay in inpatients who were admitted to the emergency department (ED) with pulmonary infiltrates who required a differential diagnosis with pulmonary tuberculosis (TB).

Methods

The patients with pulmonary infiltrates who received a QuantiFERON (QFT) test in the ED were included as an inpatient group and were divided into TB and non-TB group based on the final diagnosis. Patients with pulmonary TB who were tested in the outpatient department served as a control group.

Results

In total, 377 QFT tests were analyzed. Of the 284 inpatient QFT tests, 29.6% had an indeterminate result (35.2% in the 196 patients with non-TB and 17.0% in the 88 patients with TB). In contrast, only 1.1% of the 93 outpatients with TB returned an indeterminate result (p < 0.001). The indeterminate QFT results in the inpatient group were independently associated with lymphocytopenia, hypoalbuminemia, and high C-reactive protein levels. Non-positive QFT results in inpatients with TB were associated with lymphocytopenia and hypoalbuminemia, while non-positive QFT results in outpatients with TB were associated with high erythrocyte sedimentation rates and radiographically more severe diseases.

Conclusions

QFT tests in ED-based inpatients with pulmonary infiltrate return indeterminate results relatively frequently. In addition, inpatients and outpatients with pulmonary TB may differ in terms of the risk factors on non-positive QFT results.