title: Tuberculosis screening in patients with psoriasis before antitumour necrosis factor therapy: comparison of an interferon-gamma release assay vs. tuberculin skin test.
abstract: 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.
  
  
  CONCLUSIONS
  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.
authors: Clinic of Dermatology, University Medical Hospital, CH-1211 Geneva, Switzerland. emmanuel.laffitte@hcuge.ch
authors: E
authors: E
authors: Laffitte
authors: J P
authors: JP
authors: Janssens
authors: P
authors: P
authors: Roux-Lombard
authors: A M
authors: AM
authors: Thielen
authors: C
authors: C
authors: Barde
authors: G
authors: G
authors: Marazza
authors: R G
authors: RG
authors: Panizzon
authors: J-H
authors: JH
authors: Saurat
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000995:Antitubercular Agents / Q000627:therapeutic use*; D005260:Female; D006801:Humans; D007371:Interferon-gamma / Q000032:analysis* / Q000378:metabolism; D055985:Latent Tuberculosis / Q000175:diagnosis* / Q000276:immunology; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D011565:Psoriasis / Q000150:complications / Q000276:immunology*; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D014374:Tuberculin Test / Q000379:methods*; D014409:Tumor Necrosis Factor-alpha / Q000037:antagonists & inhibitors*; D055815:Young Adult
chemical_list: D000995:Antitubercular Agents; D014409:Tumor Necrosis Factor-alpha; D007371:Interferon-gamma