title: Sensitivity and specificity of real time polymerase chain reaction (RT-PCR) in bronchial washing for diagnostic pulmonary tuberculosis at Maharat Nakhorn Ratchasima Hospital.
abstract: OBJECTIVE
  To study sensitivity and specificity of real time polymerase chain reaction (RT-PCR) in bronchial washing for diagnostic pulmonary tuberculosis at Maharat Nakhorn Ratchasima Hospital.
  
  
  METHODS
  A retrospective study of performed bronchial washing (BW) specimens for RT-PCR TB, AFB stain, and culture TB by conventional technique from 430 patients who had undergone bronchoscopic examination due to symptomatic abnormal CXR or Chest-CT with sputum samples negative or no sputum for AFB by the authors between December 1, 2008 and September 31, 2011. TB culture was gold standard in category A. Final diagnoses was confirmed with microbiological, clinicopathological finding and response to anti-TB treatment in category B. They were analyzed to study sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), positive and negative likelihood ratios of BWRT-PCR TB on diagnostic tool for detecting pulmonary TB. Statistical analysis of the data was described as percentage.
  
  
  RESULTS
  Four hundred thirty patients were included in the presented study. Age range, sex, hemoptysis, smoking, CXR, and bronchoscope finding were not significant different between pulmonary TB and not pulmonary TB. The sensitivity, specificity, PPV NPV positive and likelihood ratios of bronchial washing for PCR-TB when applied to category A for diagnosing smear-negative pulmonary TB were 65.7%, 90.4%, 37.7%, 96.7%, 6.8, and 0.37 respectively. Category B were 43.2%, 93.3%, 62.3%, 86.4%, 6.4, and 0.6 respectively. After combination with BW AFB stain (bAFB), sensitivity was higher but specificity was less in both categories.
  
  
  CONCLUSIONS
  The low sensitivity of RT-PCR method might be low prevalence of active pulmonary TB in cases of the presented, the type of transfer and duration time (all of them were sent to a laboratory outside the hospital), the DNA extraction procedure, primer the concentration of bronchial washing for DNA amplified, DNA extraction, and reproducible technique. However, BW RT-PCR should be done in a highly suspicious case due to rapid detection. False positive should be concerned in case of treated or old lesion from pulmonary TB.
authors.affiliation: Division of Pulmonary and Critical, Department of Medicine, Maharat Nakhon Ratchasima Hospital, Nakhon Ratchasima, Thailand. Napat_kheawon@yahoo.com
authors.forename: Nabhathara
authors.initials: N
authors.lastname: Kheawon
authors.forename: Suthanya
authors.initials: S
authors.lastname: Chuang-Ngam
authors.forename: Suparat
authors.initials: S
authors.lastname: Mitsoongneun
authors.forename: Janisaya
authors.initials: J
authors.lastname: Peam-Am
authors.forename: Jarukorn
authors.initials: J
authors.lastname: Visalsawadi
mesh_terms: D001999:Bronchoscopy; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D060888:Real-Time Polymerase Chain Reaction; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D013785:Thailand; D014397:Tuberculosis, Pulmonary / Q000175:diagnosis*