Prospective evaluation of the clinical utility of interferon-γ assay in the differential diagnosis of intestinal tuberculosis and Crohn's disease.
BACKGROUND
Distinguishing intestinal tuberculosis (ITB) from Crohn's disease (CD) is challenging. This study prospectively evaluated the clinical utility of the QuantiFERON-TB gold test (QFT) in the differential diagnosis of ITB and CD, and compared it with the clinical utility of the tuberculin skin test (TST).


METHODS
Patients with suspected ITB or CD on colonoscopic findings were enrolled from 13 hospitals in Korea between June 2007 and November 2008. A QFT and TST were performed. When the initial diagnosis was not confirmed, 2-3 months of empiric antituberculous therapy was administered.


RESULTS
In all, 128 patients were analyzed; 64 patients had ITB and 64 patients had CD. The median age of patients with ITB was greater than the patients with CD (47 years versus 31 years, P < 0.001). The positive rate for the QFT and TST (≥10 mm) in patients with ITB was significantly higher than patients with CD (67% versus 9% and 69% versus 16%, respectively; P < 0.001). The QFT and TST had good agreement (κ = 0.724, P < 0.001). The diagnostic validity of QFT in ITB had a 67% sensitivity, 90% specificity, 87% positive predictive value, and 73% negative predictive value. There was no difference in these parameters between the QFT and TST. The likelihood ratio for a positive QFT was higher than a positive TST in the diagnosis of ITB (7.1 and 4.4, respectively).


CONCLUSIONS
The QFT is a limited but useful diagnostic aid in combination with the TST in the diagnosis of ITB.
Department of Internal Medicine, Chung-Ang University College of Medicine, Seoul, Korea.
Beom Jin
BJ
Kim
Yong Sung
YS
Choi
Byung Ik
BI
Jang
Young Sook
YS
Park
Won Ho
WH
Kim
You Sun
YS
Kim
Sung-Ae
SA
Jung
Dong Soo
DS
Han
Joo Sung
JS
Kim
Jai Hyun
JH
Choi
Chang Hwan
CH
Choi
Yoon Tae
YT
Jeen
Jae Hee
JH
Cheon
Byong Duk
BD
Ye
Suk-Kyun
SK
Yang
Young-Ho
YH
Kim
D000293:Adolescent; D000328:Adult; D000368:Aged; D003424:Crohn Disease / Q000097:blood / Q000175:diagnosis*; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D007371:Interferon-gamma / Q000378:metabolism*; D007410:Intestinal Diseases / Q000097:blood / Q000175:diagnosis*; D008214:Lymphocytes / Q000276:immunology / Q000378:metabolism; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014385:Tuberculosis, Gastrointestinal / Q000097:blood / Q000175:diagnosis*; D055815:Young Adult
D007371:Interferon-gamma