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

Abstract

BackgroundThis 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).MethodsThe 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.ResultsIn 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.ConclusionsQFT 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.

Diagnostic accuracy of C-reactive protein for active pulmonary tuberculosis: a meta-analysis

“…Two studies were conducted in countries with high TB/HIV burden 17,29 and the remaining three studies were conducted in countries with low to intermediate TB burden (Table 1). 21,30,31 Overall, 185 patients (28%) had pulmonary TB, and prevalence ranged from 11 to 93%. Four studies included patients infected with HIV (N=287), 17,21,29,31 including two studies that restricted enrollment to HIV-infected individuals.…”

“…Four studies included patients infected with HIV (N=287), 17,21,29,31 including two studies that restricted enrollment to HIV-infected individuals. 17,21 All studies enrolled hospitalized patients who self-reported symptoms suggestive of TB: 17,21,29–31 two studies enrolled patients with pulmonary infiltrates on chest imaging, 30,31 one study enrolled HIV-infected patients with respiratory symptoms, 21 one study enrolled HIV-infected patients with suspected smear-negative pulmonary TB, 17 and one study enrolled patients with fever of unknown origin (FUO). 29 …”

Risk factors for false-negative T-SPOT.TB assay results in patients with pulmonary and extra-pulmonary TB

“…54e56 Furthermore, it has been reported that pulmonary TB patients with non-positive QFT-TB results have more severe disease than those with positive QFT-TB results, and that the sensitivity of the QFT-TB test may be significantly different depending on disease severity. 57 Therefore, we speculated that the IFN-g production of patients with longer periods of illness before hospitalization may be depressed when stimulated with the M.TB-specific antigens in the T-SPOT.TB test, as is stimulated with sonicated M.TB strains in previous study, 55 and then results in false-negative T-SPOT.TB results in some advanced TB patients. This result is also consistent with some active TB patients showing lower numbers of spot forming cells than individuals with latent tuberculosis infection (LTBI) in the T-SPOT.TB test in clinical situations.…”

In vitro responses of multiple cytokines to purified protein derivative in healthy and naturally Mycobacterium tuberculosis‐infected rhesus monkeys (Macaca mulatta)

“…Among the cytokines secreted, IFN-γ is one of the most studied and has been used as a robust marker for functional immune responses to antigens. [2][3][4][5] Mycobacterial diseases are a primary health concern in humans and animals. Although great progress has been made in the prevention and control of tuberculosis, tuberculosis remains a global health care problem.…”

“…Accordingly, the ability to accurately measure antigen‐specific cytokine responses becomes critical to the study of infectious diseases. Among the cytokines secreted, IFN‐γ is one of the most studied and has been used as a robust marker for functional immune responses to antigens …”