title: Effect of previous treatment and sputum quality on diagnostic accuracy of Xpert®MTB/RIF.
abstract: In early studies, Xpert® MTB/RIF accurately detected culture-proven pulmonary tuberculosis (TB). Recent reports have, however, found a lower than expected specificity in previously treated TB patients.
  
  
  
  To investigate the diagnostic accuracy of Xpert in presumptive pulmonary TB patients in Southwestern Uganda.
  
  
  
  We obtained demographic and clinical information and collected three sputum samples from each patient for smear microscopy, Xpert and culture. We estimated Xpert sensitivity and specificity against culture, and stratified the analysis by previous treatment and sputum quality status.
  
  
  
  We analyzed results from 860 presumptive TB patients, including 109 (13%) with a previous history of anti-tuberculosis treatment; 205 (24%) were culture-positive. Xpert specificity was lower (91.8%, 95%CI 84.9-96.2) in previously treated than in new TB patients (97.5%, 95%CI 96.1-98.5; P = 0.01). In an adjusted analysis, patients with culture-, Xpert+ results were more likely to have been previously treated for TB (OR 8.3, 95%CI 2.1-32.0; P = 0.002), and to have mucosalivary sputum (OR 4.1, 95%CI 1.1-14.6; P = 0.03), but were less likely to self-report fever (OR 0.23, 95%CI 0.1-0.7; P = 0.008) than patients with concordant positive results.
  
  
  
  Xpert specificity was lower in previously treated patients with suspected TB. The clinical and programmatic impact of culture-, Xpert+ results requires evaluation in future studies.
authors.affiliation: Section of Infectious Diseases, Department of Medicine, Boston Medical Center and Boston University School of Medicine, Boston, Massachusetts, USA.
authors.forename: C
authors.initials: C
authors.lastname: Acuña-Villaorduña
authors.affiliation: Epicentre, Médecins Sans Frontières, Mbarara, Faculty of Medicine, Mbarara University of Science and Technology, Mbarara, Uganda.
authors.forename: P
authors.initials: P
authors.lastname: Orikiriza
authors.affiliation: Epicentre, Médecins Sans Frontières, Mbarara.
authors.forename: D
authors.initials: D
authors.lastname: Nyehangane
authors.affiliation: Department of Biostatistics, Boston University School of Public Health, Boston, Massachusetts.
authors.forename: L F
authors.initials: LF
authors.lastname: White
authors.affiliation: Epicentre, Médecins Sans Frontières, Mbarara, Faculty of Medicine, Mbarara University of Science and Technology, Mbarara, Uganda.
authors.forename: J
authors.initials: J
authors.lastname: Mwanga-Amumpaire
authors.affiliation: Department of Biostatistics, Rutgers School of Public Health, Rutgers, The State University of New Jersey, Newark, New Jersey, USA.
authors.forename: S
authors.initials: S
authors.lastname: Kim
authors.affiliation: Unité Mixte Internationale 233, Recherches Translationnelles sur le VIH et les Maladies Infectieuses, Unité 1175, Institut pour la Recherche et le Development, Institut National de la Santé et de la Recherche Médicale, Montpellier, France.
authors.forename: M
authors.initials: M
authors.lastname: Bonnet
authors.affiliation: Pulmonary Clinical Medicine Section, Cardiovascular and Pulmonary Branch, Division of Intramural Research, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland, University of Florida, Gainesville, Florida, USA.
authors.forename: K P
authors.initials: KP
authors.lastname: Fennelly
authors.affiliation: Epicentre, Médecins Sans Frontières, Mbarara, Faculty of Medicine, Mbarara University of Science and Technology, Mbarara, Uganda.
authors.forename: Y
authors.initials: Y
authors.lastname: Boum
authors.affiliation: Section of Infectious Diseases, Department of Medicine, Boston Medical Center and Boston University School of Medicine, Boston, Massachusetts, USA.
authors.forename: E C
authors.initials: EC
authors.lastname: Jones-López
mesh_terms: D000328:Adult; D000995:Antitubercular Agents / Q000008:administration & dosage*; D005260:Female; D006801:Humans; D008297:Male; D008853:Microscopy / Q000379:methods*; D008875:Middle Aged; D016133:Polymerase Chain Reaction / Q000379:methods*; D012680:Sensitivity and Specificity; D013183:Sputum / Q000382:microbiology; D014397:Tuberculosis, Pulmonary / Q000175:diagnosis* / Q000188:drug therapy; D014454:Uganda
chemical_list: D000995:Antitubercular Agents