P137. The usefulness of in vitro interferon-γ assay for differential diagnosis between intestinal tuberculosis and Crohn's disease
D.H. Baek1, G.A. Song1, D.Y. Ryu1, D.U. Kim1, 1Pusan national university hospital, Internal medicine, Busan, South Korea
It is difficult to clinically and endoscopically differentiate intestinal tuberculosis (ITB) and Crohn's disease (CD). The aim of this study was to evaluate the usefulness of in vitro interferon-gamma (IFN-γ) assay for differential diagnosis between ITB and CD.
Ninety-five patients for whom differential diagnosis between ITB and CD was difficult were enrolled between January 2007 and January 2011. The IFN-γ-producing T-cell response to early secreted antigenic target 6 and culture filtrate protein 10 were measured by T-SPOT.TB blood test in vitro. We evaluated the usefulness of T-SPOT.TB blood test by comparing its results with the final diagnosis.
Forty-five and fifty patients were revealed to be positive and negative in T-SPOT.TB blood test, respectively. Of the 45 patients found to be positive, 31 patients (68.9%) were finally diagnosed as ITB, 11 patients as CD, and 3 patients as Behcet's enterocolitis. Of the 50 patients with negative results, 48 patients (96%) were diagnosed as CD; one as Behcet's enterocolitis; one as nonspecific colitis; none as ITB. The sensitivity and specificity of T-SPOT.TB blood test for ITB were 100% and 78.1%, respectively. Positive and negative predictive values of T-SPOT.TB blood test for ITB were 68.9% and 100%, respectively.
|TB. Colitis||Non-TB. Colitis||Total|
|Sensitivity (%)||31/31 (100)|
|Specificity (%)||50/64 (78.1)|
|P(+) value (%)||31/45 (68.9)|
|P(−) value (%)||50/50 (100)|
|Intestinal tuberculosis (n = 31)||Crohn's disease (n = 59)|
|Age, years (range)||48.1 (26–78)||24.1 (17–65)|
|Male / Female||15/16||41/18|
|Symptoms or signs|
|Fever/above 38°||10/3 (32%/10%)||2/0 (3%/0%)|
|Fistula||0 (0%)||7 (11%)|
|Colonoscopic findings||0 (0%)||14 (23%)|
|Ulceration||31 (100%)||57 (96%)|
|Trans./Long./Combine.||20/5/6 (64%/16%/20%)||11/36/12 (19%/61%/20%)|
|Stricture||5 (16%)||12 (20%)|
When differential diagnosis between ITB and CD is difficult, T-SPOT.TB blood test may be a helpful and rapid diagnostic tool to exclude ITB. Prospective large-scaled studies are required for further evaluation of the usefulness of T-SPOT.TB blood test for differential diagnosis between ITB and CD.