title: Diagnostic accuracy of the Xpert® MTB/RIF assay for extra-pulmonary tuberculosis: a meta-analysis.
abstract: BACKGROUND
  Xpert(®) MTB/RIF is a commercially available nucleic acid amplification test developed for the diagnosis of pulmonary tuberculosis (PTB).
  
  
  OBJECTIVE
  To determine the diagnostic accuracy of Xpert for the detection of extra-pulmonary tuberculosis (EPTB).
  
  
  METHODS
  We searched MEDLINE, EMBASE and Global Health databases from January 2010 to 15 August 2014 for studies of diagnostic performance in which Xpert was examined against culture for patients with clinically suspected EPTB. Bivariate random effects models were used to provide pooled estimates of diagnostic accuracy.
  
  
  RESULTS
  Thirty-six studies were identified, with a pooled sensitivity and specificity of respectively 77% (95%CI 66-85) and 97% (95%CI 94-98). Substantial variations existed between study estimates of sensitivity (I(2) = 99%) and specificity (I(2) = 96%). Among site-specific estimates for lymph, pleural fluid, cerebrospinal fluid, gastro-intestinal and urinary samples, the pooled sensitivity was lower in pleural fluid (37%, 95%CI 26-50, meta-regression P < 0.001) and higher in lymph node samples (87%, 95%CI 75-95, meta-regression P = 0.03).
  
  
  CONCLUSIONS
  Xpert has high specificity but limited sensitivity for the detection of EPTB. Although positive Xpert test results may be useful in rapidly identifying EPTB cases, negative test results provide less certainty for ruling out disease.
authors: <sup>*</sup>Department of Medicine, University of Saskatchewan, Saskatoon, Saskatchewan.
authors: E
authors: E
authors: Penz
authors: <sup>†</sup>Department of Community Health Sciences, University of Calgary, Calgary.
authors: J
authors: J
authors: Boffa
authors: <sup>‡</sup>Departments of Surgery and Community Health Sciences, Intensive Care Unit Administration, Foothills Medical Centre, Calgary.
authors: D J
authors: DJ
authors: Roberts
authors: <sup>§</sup>Peter Lougheed Hospital, University of Calgary, Calgary.
authors: D
authors: D
authors: Fisher
authors: <sup>¶</sup>Royal Alexandra Hospital, Edmonton, Alberta.
authors: R
authors: R
authors: Cooper
authors: <sup>#</sup>Department of Clinical Epidemiology, Ottawa Hospital Research Institute, The Ottawa Hospital, Ottawa, Ontario.
authors: P E
authors: PE
authors: Ronksley
authors: <sup>**</sup>Departments of Medicine and Community Health Sciences, University of Calgary and the Foothills Medical Centre, Calgary, Alberta, Canada.
authors: M T
authors: MT
authors: James
mesh_terms: D000904:Antibiotics, Antitubercular / Q000627:therapeutic use; D006801:Humans; D025202:Molecular Diagnostic Techniques / Q000379:methods*; D009169:Mycobacterium tuberculosis / Q000302:isolation & purification; D021141:Nucleic Acid Amplification Techniques / Q000379:methods*; D012680:Sensitivity and Specificity; D014397:Tuberculosis, Pulmonary / Q000175:diagnosis* / Q000188:drug therapy
chemical_list: D000904:Antibiotics, Antitubercular