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Tuberculosis screening in patients with psoriasis before antitumour necrosis factor therapy: comparison of an interferon‐γ release assay vs. tuberculin skin test
Author(s) -
Laffitte E.,
Janssens J.P.,
RouxLombard P.,
Thielen A.M.,
Barde C.,
Marazza G.,
Panizzon R.G.,
Saurat J.H.
Publication year - 2009
Publication title -
british journal of dermatology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.304
H-Index - 179
eISSN - 1365-2133
pISSN - 0007-0963
DOI - 10.1111/j.1365-2133.2009.09331.x
Subject(s) - tuberculin , medicine , psoriasis , tuberculosis , skin test , immunology , tuberculin test , interferon , tumor necrosis factor alpha , interferon γ , necrosis , interferon gamma , dermatology , pathology , cytokine
Summary 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‐γ 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–Guérin (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 7·43; 95% confidence interval 1·38–39·9), which was not the case for the TST. Agreement between the T‐SPOT. TB and TST was poor, κ = 0·33 (SD 0·13). 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.