Tuberculosis screening in patients with psoriasis before antitumour necrosis factor therapy: comparison of an interferon-gamma release assay vs. tuberculin skin test

Br J Dermatol. 2009 Oct;161(4):797-800. doi: 10.1111/j.1365-2133.2009.09331.x. Epub 2009 Jun 5.


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-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, kappa = 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.

Publication types

  • Comparative Study
  • Multicenter Study

MeSH terms

  • Adolescent
  • Adult
  • Aged
  • Antitubercular Agents / therapeutic use*
  • Female
  • Humans
  • Interferon-gamma / analysis*
  • Interferon-gamma / metabolism
  • Latent Tuberculosis / diagnosis*
  • Latent Tuberculosis / immunology
  • Male
  • Middle Aged
  • Predictive Value of Tests
  • Psoriasis / complications
  • Psoriasis / immunology*
  • Retrospective Studies
  • Sensitivity and Specificity
  • Tuberculin Test / methods*
  • Tumor Necrosis Factor-alpha / antagonists & inhibitors*
  • Young Adult


  • Antitubercular Agents
  • Tumor Necrosis Factor-alpha
  • Interferon-gamma