title: Correlation between tuberculin skin test and IGRAs with risk factors for the spread of infection in close contacts with sputum smear positive in pulmonary tuberculosis.
abstract: BACKGROUND
  The aim of the study was to assess the correlation between the tuberculin skin test (TST) and in vitro interferon-gamma released assays (IGRAs) with risk factors for the spread of infection in smear positive pulmonary tuberculosis (TB) contacts.
  
  
  METHODS
  We recruited prospective contacts with smear positive pulmonary TB cases. We looked at human immunodeficiency virus (HIV) infection and other conditions of immunosuppression, presence of BCG vaccination and the degree of exposure to the index case. Patients underwent the TST, chest radiography, sputum analysis when necessary, and IGRA assays (QFN-G-IT and T-SPOT.TB). Presence of cough, diagnostic delay (days between first symptoms and TB diagnostic), contact conditions: room size (square meters) and index of overcrowding (square meters per person) were investigated in the index case.
  
  
  RESULTS
  156 contacts (119 adults, 37 children) of 66 TB patients were enrolled, 2.4 (1-14) contacts per TB case. The positivity of the TST did not correlate with the risk factors studied: presence of cough (p = 0.929); delayed diagnosis (p = 0.244); room size (p = 0.462); overcrowding (p = 0.800). Both QFN-G-IT and T-SPOT.TB, showed significant association with cough (p = 0.001, and p = 0.007) and room size (p = 0.020, and p = 0.023), respectively.
  
  
  CONCLUSIONS
  Both IGRA associated better than TST with certain host-related risk factors involved in the transmission of disease, such as the presence of cough.
authors.affiliation: Unitat de Tuberculosi de Drassanes, Hospital Universitari Vall d'Hebron, Barcelona, Spain. msouza@vhebron.net.
authors.forename: Maria Luiza
authors.initials: ML
authors.lastname: de Souza-Galvão
authors.forename: Irene
authors.initials: I
authors.lastname: Latorre
authors.forename: Neus
authors.initials: N
authors.lastname: Altet-Gómez
authors.forename: María Ángeles
authors.initials: MÁ
authors.lastname: Jiménez-Fuentes
authors.forename: Celia
authors.initials: C
authors.lastname: Milà
authors.forename: Jordi
authors.initials: J
authors.lastname: Solsona
authors.forename: Maria Asunción
authors.initials: MA
authors.lastname: Seminario
authors.forename: Adela
authors.initials: A
authors.lastname: Cantos
authors.forename: Juan
authors.initials: J
authors.lastname: Ruiz-Manzano
authors.forename: José
authors.initials: J
authors.lastname: Domínguez
mesh_terms: D000328:Adult; D001500:BCG Vaccine; D002648:Child; D002675:Child, Preschool; D003141:Communicable Diseases / Q000175:diagnosis; D003371:Cough / Q000209:etiology; D057210:Delayed Diagnosis; D005260:Female; D015658:HIV Infections / Q000150:complications; D006801:Humans; D007371:Interferon-gamma; D059425:Interferon-gamma Release Tests; D008297:Male; D011446:Prospective Studies; D012307:Risk Factors; D013183:Sputum; D014374:Tuberculin Test; D014397:Tuberculosis, Pulmonary / Q000150:complications / Q000175:diagnosis*; D055815:Young Adult
chemical_list: D001500:BCG Vaccine; D007371:Interferon-gamma