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 J Lee1†, Jaehee Lee1†, Yi Y Kim1, Dong I Won2, Seung I Cha1, Jae Y Park1, Tae H Jung1 and Chang H 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.