title: Comparison study of QuantiFERON test with tuberculin skin testing to diagnose latent tuberculosis infection among nurses working in teaching hospitals of Ahvaz, Iran.
abstract: BACKGROUND
  Prompt diagnosis and treatment of latent tuberculosis (TB) infection (LTBI) are needed to control TB. The aim of the study was to compare the performance of Quanti FERON-TB test (QFT) with conventional TST for the diagnosis of LTBI.
  
  
  METHODS
  In this analytical - comparison study, we enrolled 87 nurses working in teaching hospitals in Ahvaz. All study subjects were tested by TST. TST results were interpreted as positive if induration was more than 10 mm. If the level of QFT after stimulation was equal or greater than 0.35 IU/ml, test was considered as positive. Data were analyzed with SPSS program. QFT results compared with induration in TST and its relation to all variables were investigated.
  
  
  RESULTS
  The rate of LTB diagnosis by TST and QFT was 31% and 35.6%, respectively. There was no significant difference between TST and QFT in LTB diagnosis (P=0.62). Among the 56 subjects who were TST- negative, 14 cases (approximately 25%) were QFT- positive and 42 (75%) were QFT- negative. Among the 31 cases (35.6%) that had TST- positive, 13 (42%) were QFT-positive and 18 (58%) were QFT- negative. The overall percent agreement was 63.2% (k=0.139, P=0.69), discordance %=15.9-20.7, sensitivity= 41.5% and specificity=75.5%.
  
  
  CONCLUSIONS
  Diagnostic value of QFT is similar to TST, when there is strong clinical and epidemiological evidence of LTB in a nurse with negative TST, adding QFT to diagnostic evaluation is associated with increased rate of LTB diagnosis.
authors.affiliation: Health Research Institute, Infectious and Tropical Disease Research Center, Joundishapur University of Medical Sciences, Ahvaz, Iran.
authors.forename: Shokrollah
authors.initials: S
authors.lastname: Salmanzadeh
authors.affiliation: Joundishapur University of Medical Sciences, Ahvaz, Iran.
authors.forename: Hajar
authors.initials: H
authors.lastname: Abbasissifar
authors.affiliation: Health Research Institute, Infectious and Tropical Disease Research Center, Joundishapur University of Medical Sciences, Ahvaz, Iran.
authors.forename: Seyed Mohmmad
authors.initials: SM
authors.lastname: Alavi
keywords: Health care workers; Latent tuberculosisinfection; Quanti FERON-TB test; Tuberculin skin test