title: Interferon gamma release assays for monitoring the response to treatment for tuberculosis: A systematic review.
abstract: BACKGROUND
  The ability to monitor the response to therapy for tuberculosis (TB) and confirm adequate treatment would be a major advance. The utility of interferon gamma assays (IGRA) for this purpose remains uncertain.
  
  
  METHODS
  A systematic search of all studies investigating commercial IGRA to monitor anti-tuberculous treatment was done. Studies were included if they included an IGRA before the start of, and at least once during, treatment for active or latent TB.
  
  
  RESULTS
  We identified 30 studies, of which 24 used QuantiFERON-TB (QFT), three used T-SPOT.TB and three used both QFT and T-SPOT.TB. Most studies were done in low TB incidence countries. No uniform pattern was seen in IGRA conversion and reversion rates at the end of treatment for active or latent TB. In most studies, the majority of IGRA results remained positive at the end of treatment. In many studies, the quantitative levels of IFN-γ decreased during treatment, particularly in active TB. There was significant heterogeneity in the included studies.
  
  
  CONCLUSIONS
  While quantitative IGRA responses generally fall during treatment for TB, the large degree of variation in results between participants in each study means that IGRAs are unlikely to be useful for monitoring anti-tuberculous treatment in clinical practice for any individual patient.
authors.affiliation: Department of Paediatrics, The University of Melbourne, Murdoch Children's Research Institute, Royal Children's Hospital Melbourne, Parkville, VIC, Australia.
authors.forename: Vanessa
authors.initials: V
authors.lastname: Clifford
authors.affiliation: Department of Paediatrics, The University of Melbourne, Murdoch Children's Research Institute, Royal Children's Hospital Melbourne, Parkville, VIC, Australia.
authors.forename: Yu
authors.initials: Y
authors.lastname: He
authors.affiliation: Department of Paediatrics, The University of Melbourne, Murdoch Children's Research Institute, Royal Children's Hospital Melbourne, Parkville, VIC, Australia.
authors.forename: Christel
authors.initials: C
authors.lastname: Zufferey
authors.affiliation: Department of Paediatrics, The University of Melbourne, Murdoch Children's Research Institute, Royal Children's Hospital Melbourne, Parkville, VIC, Australia.
authors.forename: Tom
authors.initials: T
authors.lastname: Connell
authors.affiliation: Department of Paediatrics, The University of Melbourne, Murdoch Children's Research Institute, Royal Children's Hospital Melbourne, Parkville, VIC, Australia. Electronic address: nigel.curtis@rch.org.au.
authors.forename: Nigel
authors.initials: N
authors.lastname: Curtis
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000995:Antitubercular Agents / Q000627:therapeutic use*; D015415:Biomarkers / Q000378:metabolism; D002648:Child; D002675:Child, Preschool; D016903:Drug Monitoring / Q000379:methods*; D005260:Female; D054884:Host-Pathogen Interactions; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D007371:Interferon-gamma / Q000276:immunology* / Q000378:metabolism; D059425:Interferon-gamma Release Tests; D055985:Latent Tuberculosis / Q000175:diagnosis / Q000188:drug therapy* / Q000276:immunology / Q000378:metabolism / Q000382:microbiology; D008297:Male; D008875:Middle Aged; D009169:Mycobacterium tuberculosis / Q000187:drug effects* / Q000276:immunology; D011237:Predictive Value of Tests; D015203:Reproducibility of Results; D013997:Time Factors; D016896:Treatment Outcome; D055815:Young Adult
chemical_list: D000995:Antitubercular Agents; D015415:Biomarkers; C573415:IFNG protein, human; D007371:Interferon-gamma
keywords: Antibiotics; Diagnosis; Interferon gamma release assay; Monitoring; Mycobacterium tuberculosis; QuantiFERON; Systematic review; T-SPOT.TB