title: The benefits to communities and individuals of screening for active tuberculosis disease: a systematic review.
abstract: BACKGROUND
  Screening for tuberculosis (TB) disease aims to improve early TB case detection. The ultimate goal is to improve outcomes for people with TB and to reduce Mycobacterium tuberculosis transmission in the community through improved case detection, reduction in diagnostic delays and early treatment. Before screening programmes are recommended, evidence is needed of individual and/or community-level benefits.
  
  
  METHODS
  We conducted a systematic review of the literature to assess the evidence that screening for TB disease 1) initially increases the number of TB cases initiated on anti-tuberculosis treatment, 2) identifies cases earlier in the course of disease, 3) reduces mortality and morbidity, and 4) impacts on TB epidemiology.
  
  
  RESULTS
  A total of 28 798 publications were identified by the search strategy: 27 087 were excluded on initial screening and 1749 on full text review, leaving 62 publications that addressed at least one of the study questions. Screening increases the number of cases found in the short term. In many settings, more than half of the prevalent TB cases in the community remain undiagnosed. Screening tends to find cases earlier and with less severe disease, but this may be attributed to case-finding studies using more sensitive diagnostic methods than routine programmes. Treatment outcomes among people identified through screening are similar to outcomes among those identified through passive case finding. Current studies provide insufficient evidence to show that active screening for TB disease impacts on TB epidemiology.
  
  
  CONCLUSIONS
  Individual and community-level benefits from active screening for TB disease remain uncertain. So far, the benefits of earlier diagnosis on patient outcomes and transmission have not been established.
authors.affiliation: Department of Infectious Disease Epidemiology, London School of Hygiene & Tropical Medicine, London WC1E 7HT, UK. katharina.kranzer@lshtm.ac.uk
authors.forename: K
authors.initials: K
authors.lastname: Kranzer
authors.forename: H
authors.initials: H
authors.lastname: Afnan-Holmes
authors.forename: K
authors.initials: K
authors.lastname: Tomlin
authors.forename: J E
authors.initials: JE
authors.lastname: Golub
authors.forename: A E
authors.initials: AE
authors.lastname: Shapiro
authors.forename: A
authors.initials: A
authors.lastname: Schaap
authors.forename: E L
authors.initials: EL
authors.lastname: Corbett
authors.forename: K
authors.initials: K
authors.lastname: Lönnroth
authors.forename: J R
authors.initials: JR
authors.lastname: Glynn
mesh_terms: D000995:Antitubercular Agents / Q000627:therapeutic use; D003153:Community Health Services; D018563:Disease Notification; D042241:Early Diagnosis; D019317:Evidence-Based Medicine; D006801:Humans; D008403:Mass Screening / Q000379:methods; D011237:Predictive Value of Tests; D016896:Treatment Outcome; D014376:Tuberculosis / Q000175:diagnosis* / Q000188:drug therapy / Q000401:mortality / Q000635:transmission
chemical_list: D000995:Antitubercular Agents