Performance of two commercial blood IFN-gamma release assays for the detection of Mycobacterium tuberculosis infection in patient candidates for anti-TNF-alpha treatment.
The reactivation of latent tuberculosis (TB) is a major complication of tumor necrosis factor (TNF)-alpha inhibitors. Screening for TB infection is recommended before anti-TNF therapy is initiated; however, the use of tuberculin skin testing (TST) is controversial, due to the high rate of false-negative results in patients receiving immunosuppressive treatment. To compare the performance of two commercial interferon (IFN)-gamma release assays (IGRA), T-SPOT.TB (TS-TB) and QuantiFERON-TB Gold "In-tube" (QFT-GIT), with TST for the detection of TB infection in patients due to start anti-TNF therapy, 69 human immunodeficiency virus (HIV)-negative Italian patients (mean age: 45.2 +/- 12.6 years; male=39) were enrolled between September 2005 to August 2006. Patients affected by rheumatoid arthritis (n = 18), psoriatic arthritis (n = 26), ulcerous rectocolitis (n = 6), and Crohn's disease (n = 19) were tested simultaneously with TST, TS-TB, and QFT-GIT. Overall, 26% of patients were positive by TST, 30.4% by TS-TB, and 31.8% by QFT-GIT. Agreement with TST was similar (kappa = 0.21, p = 0.0002 and kappa = 0.26, p < 0.001, respectively). In 11 TST-negative cases, IFN-gamma release assays were positive. In addition, in seven Mantoux-positive cases with no TB risk factors, TST result agreement was achieved with at least one blood test. Indeterminate results were detected in 5.8% and 2.8% of cases, respectively, with TS-TB and with QFT-GIT (p = not significant [ns]). In conclusion, our results suggest that IGRAs may be helpful for screening purposes in patient candidates for anti-TNF therapy to confirm positive TST results and in selected cases when false-negative results are suspected. The utility of blood tests in patients with low or no TB risk remains to be assessed.
Bocchino
M
M
TB Infection Screening Unit, Department of Clinical and Experimental Medicine, University of Naples FEDERICO II, Monaldi Hospital, Via L. Bianchi, 5, 80131, Naples, Italy. mlbocchino@tiscali.it
Matarese
A
A
Bellofiore
B
B
Giacomelli
P
P
Santoro
G
G
Balato
N
N
Castiglione
F
F
Scarpa
R
R
Perna
F
F
Signoriello
G
G
Galati
D
D
Ponticiello
A
A
Sanduzzi
A
A
D000328:Adult; D005260:Female; D006801:Humans; D007118:Immunoassay / Q000379:methods; D007371:Interferon-gamma / Q000378:metabolism*; D007558:Italy; D008297:Male; D008875:Middle Aged; D009169:Mycobacterium tuberculosis / Q000276:immunology / Q000302:isolation & purification*; D012680:Sensitivity and Specificity; D014376:Tuberculosis / Q000175:diagnosis*
D007371:Interferon-gamma