title: Comparative performance of urinary lipoarabinomannan assays and Xpert MTB/RIF in HIV-infected individuals.
abstract: BACKGROUND
  Xpert MTB/RIF ('Xpert') and urinary lipoarabinomannan (LAM) assays offer rapid tuberculosis (TB) diagnosis, but have suboptimal sensitivity when used individually in HIV-positive patients. The yield of these tests used in combination for the diagnosis of active TB among HIV-infected TB suspects is unknown.
  
  
  METHODS
  Study of comparative diagnostic accuracy nested into a prospective study of HIV-infected individuals with signs and/or symptoms of TB in Uganda.
  
  
  METHODS
  Xpert testing of archived sputum was conducted for culture-confirmed TB cases and TB suspects in whom a diagnosis of TB was excluded. Additional testing included sputum smear microscopy, sputum culture (solid and liquid media), mycobacterial blood culture, and urinary testing for LAM using a lateral flow test ('LF-LAM') and an enzyme-linked immunosorbance assay ('ELISA-LAM').
  
  
  RESULTS
  Among 103 participants with culture-confirmed TB, sensitivity of Xpert was 76% (95% confidence interval, CI 0.66-0.84), and was superior to that of LF-LAM (49%, 95% CI 0.39-0.59, P < 0.001). Specificity was greater than 97% for both tests among 105 individuals without TB. The combination of smear microscopy and LF-LAM identified 67% (95% CI 0.57-0.76) of culture-confirmed TB cases and approached sensitivity of Xpert testing alone (P = 0.15). The sensitivity of the combination of Xpert and LF-LAM was 85% (88/103 95% CI 0.77-0.92), which was superior to either test alone (P < 0.05) and approached sensitivity of sputum liquid culture testing (94%, 95% CI 0.88-0.98, P = 0.17).
  
  
  CONCLUSIONS
  Sputum Xpert and urinary LAM assays were complementary for the diagnosis of active TB in HIV-infected patients, and sensitivity of the combination of these tests was superior to that of either test alone.
authors.affiliation: aJohns Hopkins University School of Medicine, Baltimore, Maryland, USA bDepartment of Microbiology cInfectious Diseases Institute, Makerere University College of Health Sciences, Kampala, Uganda dBoston Medical Center, Boston University School of Medicine, Boston, Massachusetts, USA.
authors.forename: Maunank
authors.initials: M
authors.lastname: Shah
authors.forename: Willy
authors.initials: W
authors.lastname: Ssengooba
authors.forename: Derek
authors.initials: D
authors.lastname: Armstrong
authors.forename: Lydia
authors.initials: L
authors.lastname: Nakiyingi
authors.forename: Molly
authors.initials: M
authors.lastname: Holshouser
authors.forename: Jerrold J
authors.initials: JJ
authors.lastname: Ellner
authors.forename: Moses
authors.initials: M
authors.lastname: Joloba
authors.forename: Yukari C
authors.initials: YC
authors.lastname: Manabe
authors.forename: Susan E
authors.initials: SE
authors.lastname: Dorman
mesh_terms: D000328:Adult; D002846:Chromatography, Affinity / Q000379:methods*; D005260:Female; D015658:HIV Infections / Q000150:complications*; D006801:Humans; D008070:Lipopolysaccharides / Q000652:urine*; D008297:Male; D025202:Molecular Diagnostic Techniques / Q000379:methods*; D011446:Prospective Studies; D012463:Saliva / Q000382:microbiology*; D012680:Sensitivity and Specificity; D014376:Tuberculosis / Q000175:diagnosis*; D014454:Uganda
chemical_list: D008070:Lipopolysaccharides; C050016:lipoarabinomannan