title: Performance of whole-blood interferon-gamma release assay in patients admitted to the emergency department with pulmonary infiltrates.
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.
authors.affiliation: Department of Internal Medicine, Kyungpook National University, School of Medicine, Daegu, Republic of Korea.
authors.forename: Yoon Jee
authors.initials: YJ
authors.lastname: Lee
authors.forename: Jaehee
authors.initials: J
authors.lastname: Lee
authors.forename: Yi Young
authors.initials: YY
authors.lastname: Kim
authors.forename: Dong Il
authors.initials: DI
authors.lastname: Won
authors.forename: Seung Ick
authors.initials: SI
authors.lastname: Cha
authors.forename: Jae Yong
authors.initials: JY
authors.lastname: Park
authors.forename: Tae Hoon
authors.initials: TH
authors.lastname: Jung
authors.forename: Chang Ho
authors.initials: CH
authors.lastname: Kim
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D019937:Diagnostic Techniques and Procedures / Q000295:instrumentation; D004636:Emergency Service, Hospital; D005260:Female; D006801:Humans; D007371:Interferon-gamma / Q000097:blood*; D059425:Interferon-gamma Release Tests; D008297:Male; D008875:Middle Aged; D009169:Mycobacterium tuberculosis / Q000276:immunology; D010045:Outpatients; D011446:Prospective Studies; D011933:Reagent Kits, Diagnostic; D014397:Tuberculosis, Pulmonary / Q000097:blood / Q000175:diagnosis* / Q000276:immunology*
chemical_list: D011933:Reagent Kits, Diagnostic; D007371:Interferon-gamma