Ovid: Welcome to Ovid

Tuberculosis screening in patients with psoriasis before antitumour necrosis factor therapy: comparison of an interferon-[gamma] release assay vs. tuberculin skin test.
Laffitte, E.; Janssens, J. P. *; Roux-Lombard, P. +; Thielen, A. M.; Barde, C.; Marazza, G.; Panizzon, R. G. ++; Saurat, J.-H.
[Article] British Journal of Dermatology. 161(4):797-800, October 2009.

(Format: HTML, PDF)

Background: Antitumour necrosis factor (anti-TNF) treatments may reactivate latent tuberculosis infection (LTBI). For detecting LTBI, the tuberculin skin test (TST) has low sensitivity and specificity. Interferon-[gamma] release assays (IGRA) have been shown to be more sensitive and specific than TST.

Objective: To compare the TST and the T-SPOT.TB IGRA for identifying LTBI in patients with psoriasis before anti-TNF treatment.

Methods: A retrospective study was carried out over a 4-year period on patients with psoriasis requiring anti-TNF treatment. All were subjected to the TST, T-SPOT.TB and chest X-ray. Risk factors for LTBI and history of bacillus Calmette-Guerin (BCG) vaccination were recorded. The association of T-SPOT.TB and TST results with risk factors for LTBI was tested through univariate logistic regression models. Agreement between tests was quantified using kappa statistics. Treatment for LTBI was started 1 month before anti-TNF therapy when indicated.

Results: Fifty patients were included; 90% had prior BCG vaccination. A positive T-SPOT.TB was strongly associated with a presumptive diagnosis of LTBI (odds ratio 7[middle dot]43; 95% confidence interval 1[middle dot]38-39[middle dot]9), which was not the case for the TST. Agreement between the T-SPOT.TB and TST was poor, [kappa] = 0[middle dot]33 (SD 0[middle dot]13). LTBI was detected and treated in 20% of the patients. In 20% of the cases, LTBI was not retained in spite of a positive TST but a negative T-SPOT.TB. All patients received an anti-TNF agent for a median of 56 weeks (range 20-188); among patients with a positive TST/negative T-SPOT.TB, no tuberculosis was detected with a median follow-up of 64 weeks (44-188). One case of disseminated tuberculosis occurred after 28 weeks of adalimumab treatment in a patient with LTBI in spite of treatment with rifampicin.

Conclusion: This study is the first to underline the frequency of LTBI in patients with psoriasis (20%), and to support the use of IGRA instead of the TST for its detection. Nevertheless, there is still a risk of tuberculosis under anti-TNF therapy, even if LTBI is correctly diagnosed and treated.