title: Diagnosis of latent tuberculosis infection with T-SPOT(®).TB in a predominantly immigrant population with rheumatologic disorders.
abstract: OBJECTIVE
  The objective of this study is to compare how likely positive tuberculin skin test (TST) and T-SPOT(®).TB (TSPOT) results predict risk factors for tuberculosis in a predominantly immigrant patient population at risk of latent TB infection (LTBI) and with rheumatologic conditions requiring immunomodulatory therapy (IMT).
  
  
  METHODS
  Prospective study conducted at a referral rheumatology clinic. Inclusion criteria included patients on various IMT, including immunosuppressive drugs that could predispose to TB progression. We studied risk factors associated with LTBI, test results, and tests' agreement.
  
  
  RESULTS
  We studied 101 patients. Eighty (79.2 %) were from countries where TB is prevalent and Bacille Calmette-Guérin vaccination is placed routinely. Seventy-four (73.3 %) had rheumatoid arthritis and 92 (90.7 %) were on IMT. Among patients with both TST and TSPOT results, 25 (30.9 %) were TST(+) and 20 (24.7 %) had TSPOT(+) results. Fifteen patients (18.5 %) had TST(+)/TSPOT(+) results, and 51 (63.0 %) had TST(-)/TSPOT(-) results (agreement = 81.5 %; kappa = .54 [95 % CI, .34-.74; P < .001]). Each TSPOT(+) and TST(+) results were independently associated with immigrant status and prior residence in a TB prevalent country after adjustment for immunosuppressive therapy: Adjusted OR(TSPOT+)=6.6 (95 % CI, 1.2-123.3; P = .027); and adjusted OR(TST+)=11.2 (95 % CI, 2.0-209.5; P = .003). Seven out of 10 TST(+)/TSPOT(-) cases had a TST ≥15 mm induration, including three cases with history of TST conversion.
  
  
  CONCLUSIONS
  TST(+) and TSPOT(+) results predict risk factors associated with LTBI independent of immunosuppressive IMT. Some TST(+)/TSPOT(-) results were unlikely to be false-negatives. The combined use of TST and TSPOT appears to be a reasonable diagnostic strategy to evaluate for LTBI in this population.
authors.affiliation: Division of Pulmonary and Critical Care Medicine and Mayo Clinic Center for Tuberculosis, Mayo Clinic, 200 First Street SW, Rochester, MN, 55905, USA, escalante.patricio@mayo.edu.
authors.forename: Patricio
authors.initials: P
authors.lastname: Escalante
authors.forename: Kirstin J
authors.initials: KJ
authors.lastname: Kooda
authors.forename: Rizwana
authors.initials: R
authors.lastname: Khan
authors.forename: San San
authors.initials: SS
authors.lastname: Aye
authors.forename: Stratos
authors.initials: S
authors.lastname: Christianakis
authors.forename: Daniel G
authors.initials: DG
authors.lastname: Arkfeld
authors.forename: Glenn R
authors.initials: GR
authors.lastname: Ehresmann
authors.forename: Jens J
authors.initials: JJ
authors.lastname: Kort
authors.forename: Brenda E
authors.initials: BE
authors.lastname: Jones
mesh_terms: D054242:Emigrants and Immigrants; D058501:Enzyme-Linked Immunospot Assay; D005188:False Negative Reactions; D006801:Humans; D016867:Immunocompromised Host; D007166:Immunosuppressive Agents / Q000009:adverse effects / Q000627:therapeutic use*; D055985:Latent Tuberculosis / Q000175:diagnosis* / Q000453:epidemiology / Q000276:immunology; D008910:Minnesota / Q000453:epidemiology; D011237:Predictive Value of Tests; D015995:Prevalence; D011446:Prospective Studies; D012216:Rheumatic Diseases / Q000175:diagnosis / Q000188:drug therapy* / Q000453:epidemiology / Q000276:immunology; D018570:Risk Assessment; D012307:Risk Factors; D014374:Tuberculin Test
chemical_list: D007166:Immunosuppressive Agents