Diagnosis of tuberculous uveitis: clinical application of an interferon-gamma release assay.
OBJECTIVE
To determine the role of the QuantiFERON-TB Gold In-Tube (QFT) (Cellestis Inc., Carnegie, Australia) assay in the diagnosis of tuberculosis (TB) uveitis.


METHODS
Retrospective cohort study.


METHODS
The study included 157 patients with suspected TB uveitis seen over an 18-month period (August 1, 2006, to February 31, 2007) at the Singapore National Eye Center (SNEC) uveitis clinic.


METHODS
We identified all cases of suspected TB uveitis in the above-mentioned time period and reviewed all medical records of the cases. Clinical findings, type of treatment instituted, response to treatment, and results of investigations such as QFT, tuberculin skin test (TST), and chest x-rays were recorded. A novel method of using treatment response to determine the presumed diagnosis of TB was used to estimate the accuracy of QFT and TST.


METHODS
The positive likelihood ratio (LR+), negative likelihood ratio (LR-), and area under the receiver operator characteristic curve (ROC) of the investigations were estimated.


RESULTS
QFT is not superior to the TST in sensitivity as a screening test or first-line study in TB-related uveitis; however, QFT is more specific than the TST in identifying infections by Mycobacterium tuberculosis. Negative QFT tests should be interpreted with caution, because they do not exclude the diagnosis.


CONCLUSIONS
The new QFT is only slightly superior to the TST in the diagnosis of TB uveitis. Thus, there is an important role for interpreting the QFT together with the TST. This is the first and largest study of its kind to evaluate the use of QFT in the clinical diagnosis of TB uveitis.
Ang
Marcus
M
Singapore National Eye Centre, Singapore.
Htoon
Hla Myint
HM
Chee
Soon-Phaik
SP
D000328:Adult; D000995:Antitubercular Agents / Q000627:therapeutic use; D019540:Area Under Curve; D004359:Drug Therapy, Combination; D004797:Enzyme-Linked Immunosorbent Assay; D005189:False Positive Reactions; D005260:Female; D006801:Humans; D007371:Interferon-gamma / Q000097:blood*; D007538:Isoniazid / Q000627:therapeutic use; D008168:Lung / Q000000981:diagnostic imaging; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D011718:Pyrazinamide / Q000627:therapeutic use; D012372:ROC Curve; D011859:Radiography; D011933:Reagent Kits, Diagnostic; D012189:Retrospective Studies; D012293:Rifampin / Q000627:therapeutic use; D012680:Sensitivity and Specificity; D014374:Tuberculin Test; D014392:Tuberculosis, Ocular / Q000097:blood / Q000175:diagnosis* / Q000188:drug therapy; D014605:Uveitis / Q000097:blood / Q000175:diagnosis* / Q000188:drug therapy
D000995:Antitubercular Agents; D011933:Reagent Kits, Diagnostic; D011718:Pyrazinamide; D007371:Interferon-gamma; D007538:Isoniazid; D012293:Rifampin