title: Trends in use of genotypic resistance testing and frequency of major drug resistance among antiretroviral-naive persons in the HIV Outpatient Study, 1999-2011.
abstract: BACKGROUND
  Monitoring antiretroviral drug resistance can inform treatment recommendations; however, there are few such data from US patients before they initiate ART.
  
  
  METHODS
  We analysed data from HIV Outpatient Study (HOPS) participants from nine US HIV clinics who were diagnosed with HIV infection during 1999-2011. Using the IAS-USA December 2010 guidelines, we assessed the frequency of major drug resistance mutations (mDRMs) related to antiretroviral agents in viral isolates from patients who underwent commercial genotypic testing (GT) for resistance before initiating ART. We employed general linear regression models to assess factors associated with having undergone GT, and then factors associated with having mDRM.
  
  
  RESULTS
  Among 1531 eligible patients, 758 (49.5%) underwent GT before first ART, increasing from 15.5% in 1999-2002 to 75.9% in 2009-11 (P < 0.001). GT was carried out a median of 1.2 months after the diagnosis of HIV. In adjusted regression analyses, patients with pre-ART CD4+ T lymphocyte counts ≥200 cells/mm(3) or with HIV RNA levels >5.0 log10 copies/mL and those with a first HOPS visit in 2006 or later were significantly (P < 0.05) more likely to have undergone GT. Of the 758 patients, 114 (15.0%) had mDRMs; mutations relating to NRTIs, NNRTIs and PIs were present in 8.0%, 7.1% and 2.6%, respectively. There was no temporal change in the frequency of mDRM, and mDRMs were associated with an HIV RNA level <4.0 log10 copies/mL.
  
  
  CONCLUSIONS
  During 1999-2011, GT use among antiretroviral-naive patients became more common, but a quarter of patients in recent years remained untested. The frequency of mDRMs remained stable over time at about 15%.
authors.affiliation: Division of HIV/AIDS Prevention, Centers for Disease Control and Prevention, Atlanta, GA, USA acu7@cdc.gov.
authors.forename: Kate
authors.initials: K
authors.lastname: Buchacz
authors.affiliation: APEX Family Medicine, Denver, CO, USA International Association of Providers of AIDS Care, Washington, DC, USA.
authors.forename: Benjamin
authors.initials: B
authors.lastname: Young
authors.affiliation: Northwestern University, Chicago, IL, USA.
authors.forename: Frank J
authors.initials: FJ
authors.lastname: Palella
authors.affiliation: Cerner Corporation, Vienna, VA, USA.
authors.forename: Carl
authors.initials: C
authors.lastname: Armon
authors.affiliation: Division of HIV/AIDS Prevention, Centers for Disease Control and Prevention, Atlanta, GA, USA.
authors.forename: John T
authors.initials: JT
authors.lastname: Brooks
mesh_terms: D000328:Adult; D000368:Aged; D024882:Drug Resistance, Viral; D005260:Female; D060005:Genotyping Techniques / Q000379:methods* / Q000706:statistics & numerical data; D006678:HIV / Q000235:genetics* / Q000302:isolation & purification; D015658:HIV Infections / Q000821:virology*; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D008826:Microbial Sensitivity Tests / Q000379:methods / Q000706:statistics & numerical data; D008875:Middle Aged; D010045:Outpatients; D011446:Prospective Studies; D014481:United States
keywords: HIV infection; epidemiology; genotype; mutation; primary; transmitted