title: Global burden of transmitted HIV drug resistance and HIV-exposure categories: a systematic review and meta-analysis.
abstract: OBJECTIVE
  Our aim was to review the global disparities of transmitted HIV drug resistance (TDR) in antiretroviral-naive MSM, people who inject drugs (PWID) and heterosexual populations in both high-income and low/middle-income countries.
  
  
  METHODS
  We undertook a systematic review of the peer-reviewed English literature on TDR (1999-2013). Random-effects meta-analyses were performed to pool TDR prevalence and compare the odds of TDR across at-risk groups.
  
  
  RESULTS
  A total of 212 studies were included in this review. Areas with greatest TDR prevalence were North America (MSM: 13.7%, PWID: 9.1%, heterosexuals: 10.5%); followed by western Europe (MSM: 11.0%, PWID: 5.7%, heterosexuals: 6.9%) and South America (MSM: 8.3%, PWID: 13.5%, heterosexuals: 7.5%). Our data indicated disproportionately high TDR burdens in MSM in Oceania (Australia 15.5%), eastern Europe/central Asia (10.2%) and east Asia (7.8%). TDR epidemics have stabilized in high-income countries, with a higher prevalence (range 10.9-12.6%) in MSM than in PWID (5.2-8.3%) and heterosexuals (6.4-9.0%) over 1999-2013. In low/middle-income countries, TDR prevalence in all at-risk groups in 2009-2013 almost doubled than that in 2004-2008 (MSM: 7.8 vs. 4.2%, P = 0.011; heterosexuals: 4.1 vs. 2.6%, P < 0.001; PWID: 4.8 vs. 2.4%, P = 0.265, respectively). The risk of TDR infection was significantly greater in MSM than that in heterosexuals and PWID. We observed increasing trends of resistance to non-nucleoside reverse transcriptase and protease inhibitors among MSM.
  
  
  CONCLUSIONS
  TDR prevalence is stabilizing in high-income countries, but increasing in low/middle-income countries. This is likely due to the low, but increasing, coverage of antiretroviral therapy in these settings. Transmission of TDR is most prevalent among MSM worldwide.
authors.affiliation: aThe Kirby Institute, University of New South Wales, Sydney, New South Wales, Australia bDepartment for Disease Control and Prevention, The Pasteur Institute, Ho Chi Minh City, Vietnam.
authors.forename: Quang D
authors.initials: QD
authors.lastname: Pham
authors.forename: David P
authors.initials: DP
authors.lastname: Wilson
authors.forename: Matthew G
authors.initials: MG
authors.lastname: Law
authors.forename: Anthony D
authors.initials: AD
authors.lastname: Kelleher
authors.forename: Lei
authors.initials: L
authors.lastname: Zhang
mesh_terms: D019049:Developed Countries; D003906:Developing Countries; D024882:Drug Resistance, Viral; D004363:Drug Utilization; D014943:Global Health; D006678:HIV / Q000187:drug effects* / Q000302:isolation & purification; D015658:HIV Infections / Q000453:epidemiology* / Q000635:transmission* / Q000821:virology; D006801:Humans; D015995:Prevalence