QuantiFERON-TB Gold in the identification of latent tuberculosis infection in rheumatoid arthritis: a pilot study.
OBJECTIVE
To compare the performance of QuantiFERON-TB Gold (QFT-G) with that of the tuberculin skin test (TST) in detecting latent tuberculosis (LTBI) among patients with rheumatoid arthritis (RA).


METHODS
A total of 35 RA patients and 15 healthy controls underwent TST, QFT-G assays and chest X-ray and filled out a questionnaire on predisposing conditions for TB disease. Serum interferon gamma (IFN-gamma) levels were tested by an enzyme-linked immunosorbent assay.


RESULTS
Forty-five per cent of RA patients had a TST > 5 mm vs. 26% in healthy controls. In the RA patients, QFT-G was positive in 11.4%, negative in 60% and indeterminate in 28.6%. The overall agreement between TST and QFT-G was significantly lower in the RA population than in controls (56% vs. 84%). No correlation was found between the use of prednisone, methotrexate and QFT-G results or agreement between TST and QFT-G. A low IFN-gamma level (<4 pg/ml) was found in 51.5% of the RA patients. No correlation was found between serum IFN-gamma levels and QFT-G results.


CONCLUSIONS
The clinical significance of negative QFT-G in TST-positive patients with low TB risk remains to be assessed. The high rate of indeterminate results questions the clinical utility of QFT-G in the diagnosis of LTBI in RA patients.
Department of Rheumatology, Tel Aviv Medical Center, Tel Aviv, Israel.
O
O
Shovman
M
M
Anouk
N
N
Vinnitsky
U
U
Arad
D
D
Paran
I
I
Litinsky
D
D
Caspi
O
O
Elkayam
D018501:Antirheumatic Agents / Q000627:therapeutic use; D001172:Arthritis, Rheumatoid / Q000150:complications* / Q000188:drug therapy; D015415:Biomarkers / Q000097:blood; D016022:Case-Control Studies; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D006801:Humans; D007371:Interferon-gamma / Q000097:blood*; D055985:Latent Tuberculosis / Q000175:diagnosis* / Q000000981:diagnostic imaging / Q000382:microbiology; D008297:Male; D008727:Methotrexate / Q000627:therapeutic use; D008875:Middle Aged; D009161:Mycobacterium / Q000276:immunology*; D010865:Pilot Projects; D011237:Predictive Value of Tests; D011241:Prednisone / Q000627:therapeutic use; D011859:Radiography; D011933:Reagent Kits, Diagnostic; D011795:Surveys and Questionnaires; D014374:Tuberculin Test
D018501:Antirheumatic Agents; D015415:Biomarkers; D011933:Reagent Kits, Diagnostic; D007371:Interferon-gamma; D011241:Prednisone; D008727:Methotrexate