title: On the spread and control of MDR-TB epidemics: an examination of trends in anti-tuberculosis drug resistance surveillance data.
abstract: BACKGROUND
  Multidrug resistant tuberculosis (MDR-TB) poses serious challenges for tuberculosis control in many settings, but trends of MDR-TB have been difficult to measure.
  
  
  METHODS
  We analyzed surveillance and population-representative survey data collected worldwide by the World Health Organization between 1993 and 2012. We examined setting-specific patterns associated with linear trends in the estimated per capita rate of MDR-TB among new notified TB cases to generate hypotheses about factors associated with trends in the transmission of highly drug resistant tuberculosis.
  
  
  RESULTS
  59 countries and 39 sub-national settings had at least three years of data, but less than 10% of the population in the WHO-designated 27-high MDR-TB burden settings were in areas with sufficient data to track trends. Among settings in which the majority of MDR-TB was autochthonous, we found 10 settings with statistically significant linear trends in per capita rates of MDR-TB among new notified TB cases. Five of these settings had declining trends (Estonia, Latvia, Macao, Hong Kong, and Portugal) ranging from decreases of 3% to 14% annually, while five had increasing trends (four individual oblasts of the Russian Federation and Botswana) ranging from 14% to 20% annually. In unadjusted analysis, better surveillance indicators and higher GDP per capita were associated with declining MDR-TB, while a higher existing absolute burden of MDR-TB was associated with an increasing trend.
  
  
  CONCLUSIONS
  Only a small fraction of countries in which the burden of MDR-TB is concentrated currently have sufficient surveillance data to estimate trends in drug-resistant TB. Where trend analysis was possible, smaller absolute burdens of MDR-TB and more robust surveillance systems were associated with declining per capita rates of MDR-TB among new notified cases.
authors.affiliation: Brigham and Women's Hospital, Division of Global Health Equity, Boston, MA 02115, USA; Harvard School of Public Health, Department of Epidemiology, Boston, MA 02115, USA. Electronic address: theodore.cohen@yale.edu.
authors.forename: Ted
authors.initials: T
authors.lastname: Cohen
authors.affiliation: Brigham and Women's Hospital, Division of Global Health Equity, Boston, MA 02115, USA; Harvard Medical School, Boston, MA 02115, USA.
authors.forename: Helen E
authors.initials: HE
authors.lastname: Jenkins
authors.affiliation: Brigham and Women's Hospital, Division of Global Health Equity, Boston, MA 02115, USA; Harvard Medical School, Department of Global Health and Social Medicine, Boston, MA 02115, USA.
authors.forename: Chunling
authors.initials: C
authors.lastname: Lu
authors.affiliation: Harvard Medical School, Boston, MA 02115, USA.
authors.forename: Megan
authors.initials: M
authors.lastname: McLaughlin
authors.affiliation: Global TB Programme, TB Monitoring and Evaluation, World Health Organization, Geneva, Switzerland.
authors.forename: Katherine
authors.initials: K
authors.lastname: Floyd
authors.affiliation: Global TB Programme, TB Monitoring and Evaluation, World Health Organization, Geneva, Switzerland.
authors.forename: Matteo
authors.initials: M
authors.lastname: Zignol
mesh_terms: D000995:Antitubercular Agents / Q000627:therapeutic use*; D006801:Humans; D011159:Population Surveillance / Q000379:methods; D018088:Tuberculosis, Multidrug-Resistant / Q000188:drug therapy* / Q000453:epidemiology*; D014944:World Health Organization
chemical_list: D000995:Antitubercular Agents
keywords: Antibiotic resistance; MDR; Multidrug resistance; Surveillance; Trend; Tuberculosis