Tuberculosis Research and Treatment

Research Article

Tuberculin Skin Tests versus Interferon-Gamma Release Assays in Tuberculosis Screening among Immigrant Visa Applicants

Table 1

Subject characteristics and test results of US-bound immigrant visa applicants in Vietnam.
Characteristics 
Subjects evaluated:
Age in years: 
 Mean/median38.5/37.5
 Minimum/maximum18.0/86.0
Sex: number (%) 
 Female842 (67.6)
 Male404 (32.4)
Country of birth: (%) 
 Vietnam1235 (99.1)
 Other (China or Cambodia)11 (0.9)
Prior history of TB7 (0.6)
Reported prior contact with a TB patient: (%) 
 Any contact96 (7.7)
 Household contact93 (7.5)
TB symptoms*: (%) 3 (0.2)
Other major medical conditions**: (%) 17 (1.4)
BCG vaccination status***: (%) 
 Not vaccinated735 (59.0)
 Vaccinated511 (41.0)
HIV test results: (%) 
 Negative1239 (99.4)
 Positive7 (0.6)
Chest examination: (%) 
 Normal1239 (99.4)
 Abnormal7 (0.6)
Chest radiograph: (%) 
 Normal or not consistent with TB****974 (78.2)
 Findings consistent with TB272 (21.8)
TST results: (%) 
 <5 mm278 (22.3)
 5 to 9 mm247 (19.8)
 10 to 14 mm403 (32.3)
 ≥15 mm318 (25.5)
QFT results: (%) 
 Negative for MTB infection without M. avium reactivity234 (18.8)
 Negative for MTB infection with M. avium reactivity362 (29.1)
 Positive for MTB infection564 (45.3)
 Indeterminate86 (6.9)
QFT-G results: (%) 
 Negative811 (65.1)
 Positive352 (28.3)
 Indeterminate83 (6.7)
: number in subset of ; TB: tuberculosis; BCG: bacille Calmitte-Guérin; HIV: human immunodeficiency virus; MTB: Mycobacteria tuberculosis; TST: tuberculin skin test; QFT: QuantiFERON-TB test; QFT-G: QuantiFERON-TB Gold test.
*TB Symptoms included cough, dyspnea, fever, unintended weight loss, and hemoptysis.
**Other major medical conditions included diabetes, renal failure, silicosis, gastrectomy, and malignancies.
***Reported BCG status based on interview. All subjects reporting BCG vaccination also had scars compatible with vaccination history.
****Chest radiographs were normal for 967 subjects while 7 subjects had abnormal chest radiographs with lesions not consistent with TB (e.g., fractured rib or cardiac enlargement).