Comparison of QuantiFERON-TB Gold test and tuberculin skin test for the identification of latent Mycobacterium tuberculosis infection in lupus patients

N Yilmaz, S Zehra Aydin, N Inanc, S Karakurt, H Direskeneli, S Yavuz
Lupus 2012, 21 (5): 491-5

UNLABELLED: The tuberculin skin test (TST) has low sensitivity for the diagnosis of tuberculosis (TB). QuantiFERON-TB Gold (QFT-G) is an IFN-gamma-release assay that measures the release of interferon-gamma after stimulation in vitro by Mycobacterium tuberculosis antigens using ELISA. The main advantage of this assay compared with TST is the lack of cross-reaction with Bacillus Calmette-Guérin (BCG) as well as most of non-tuberculous mycobacteria. The aim of our study is to compare QFT-G with TST for the detection of latent tuberculosis infection (LTBI) among patients with systemic lupus erythematosus (SLE).

METHODS: Seventy-eight patients with SLE and 49 healthy subjects (HCs) participated in the study. All patients and controls were interviewed for a history of TB then BCG vaccinations were recorded and chest X-rays were examined for a sign of TB infection. QTF-G and TST were performed on both patients and controls. QTF-G results were recorded as positive, negative or indeterminate. A positive TST for SLE was defined as ≥5 mm.

RESULTS: Seventy-six SLE patients (97.4%) had been BCG vaccinated. Similar to the HC (28.5%), 19 of 78 (24.3%) SLE patients had positive QTF-G. Two patients had an indeterminate result. The agreement between QTF-G and TST was 49/76 (64.4%) (κ = 0.33). There were fewer positive QFT-G test results than positive TST results (24.3% vs. 50%; p < 0.01). Twenty-two (28.9%) patients were TST(+)/QTF-G(-) while only 3(3.9%) patients were TST(-)/QTF-G(+). When the positive TST was defined as ≥10 mm indurations, which is the cut-off in screening for LTBI in Turkey, the agreement between two tests increased up to 58/76 (76.3%) with a κ value of 0.47. The mean TST measurements was higher in QTF-G positive patients (13.4 ± 8.8 mm) than the QTF-G negative patients (4 ± 5.3 mm) (p < 0.001).

DISCUSSION: In a TB-endemic and BCG vaccinated population, the QuantiFERON-TB Gold assay seemed to be a more accurate test for the detection of LTBI in SLE patients. Although 5 mm is usually accepted to be the standard cut-off for TST in immunocompromised patients such as SLE, the level of agreement between QTF-G and TST was better with a 10 mm cut-off in our population.

Full Text Links

Find Full Text Links for this Article


You are not logged in. Sign Up or Log In to join the discussion.

Related Papers

Remove bar
Read by QxMD icon Read

Save your favorite articles in one place with a free QxMD account.


Search Tips

Use Boolean operators: AND/OR

diabetic AND foot
diabetes OR diabetic

Exclude a word using the 'minus' sign

Virchow -triad

Use Parentheses

water AND (cup OR glass)

Add an asterisk (*) at end of a word to include word stems

Neuro* will search for Neurology, Neuroscientist, Neurological, and so on

Use quotes to search for an exact phrase

"primary prevention of cancer"
(heart or cardiac or cardio*) AND arrest -"American Heart Association"