Evaluation of an interferon-gamma release assay, T-SPOT.TB, in a population with a low prevalence of tuberculosis.
METHODS
Great Lakes, Illinois, USA.


OBJECTIVE
To compare the performance of an interferon-gamma release assay (T-SPOT.TB) and tuberculin skin test (TST) in a population with a low prevalence of tuberculosis (TB) that was predominantly US-born and not bacille Calmette-Guérin-vaccinated.


METHODS
A total of 414 subjects with absence of a previous positive TST were enrolled, of whom 326 yielded analyzable results for both TST and T-SPOT.TB.


RESULTS
Overall agreement between T-SPOT.TB and TST was 98.2% (95%CI 96.0-99.3). The specificity of T-SPOT.TB in individuals judged to be at low risk for TB infection was 98.9% (95%CI 96.9-99.8). Of 326 subjects, 8 (2.5%) had a positive T-SPOT.TB result, six of which occurred in the absence of a positive TST. Of these, at least three appeared to have risk factors, suggesting the possibility of a false-negative TST result.


CONCLUSIONS
Because of the excellent agreement between the TSPOT.TB and the TST, either test can serve as an effective diagnostic tool in populations at low risk for TB. As the tests have specific advantages and disadvantages, health care providers have leeway in choosing the most appropriate test for the population they are treating.
Bienek
D R
DR
Naval Institute for Dental and Biomedical Research, Great Lakes, Illinois, USA. diane.bienek@med.navy.mil
Chang
C K
CK
D000293:Adolescent; D000328:Adult; D015415:Biomarkers / Q000097:blood; D005188:False Negative Reactions; D005260:Female; D006801:Humans; D007087:Illinois / Q000453:epidemiology; D007371:Interferon-gamma / Q000097:blood*; D008297:Male; D009169:Mycobacterium tuberculosis / Q000276:immunology*; D011237:Predictive Value of Tests; D015995:Prevalence; D011933:Reagent Kits, Diagnostic; D018570:Risk Assessment; D012307:Risk Factors; D012680:Sensitivity and Specificity; D014374:Tuberculin Test; D014376:Tuberculosis / Q000175:diagnosis* / Q000453:epidemiology / Q000382:microbiology; D055815:Young Adult
D015415:Biomarkers; D011933:Reagent Kits, Diagnostic; D007371:Interferon-gamma