title: Increase in transmitted HIV drug resistance among persons undergoing genotypic resistance testing in Ontario, Canada, 2002-09.
abstract: OBJECTIVE
  To characterize persons undergoing HIV genotypic resistance testing (GRT) while treatment naive and to estimate the prevalence of transmitted HIV drug resistance (TDR) among HIV-positive outpatients in Ontario, Canada.
  
  
  METHODS
  We analysed data from a multi-site cohort of persons receiving HIV care. Data were obtained from medical chart abstractions, interviews and record linkage with the Public Health Laboratories, Public Health Ontario. The analysis was restricted to 626 treatment-naive persons diagnosed in 2002-09. TDR mutations were identified using the calibrated population resistance tool. We used descriptive statistics and regression methods to characterize treatment-naive GRT test uptake and patterns of TDR.
  
  
  RESULTS
  Overall, 53.2% (333/626) of participants had baseline GRT. The proportion increased with year of HIV diagnosis from 30.0% in 2002 to 82.6% in 2009 (P < 0.0001). Among those tested, 13.6% (CI 9.9-17.3%) had one or more drug resistance mutations, and 8.8% (CI 5.7-11.8%), 4.8% (CI 2.5-7.2%) and 2.7% (CI 1.0-4.5%) had mutations conferring resistance to nucleoside/tide reverse transcriptase inhibitors (NRTIs), non-nucleoside reverse transcriptase inhibitors (NNRTIs) and protease inhibitors (PIs), respectively. TDR prevalence increased from 2002-07 to 2008-09 (adjusted OR 3.7, 95% CI 1.7-8.2), driven by a higher proportion with NRTI (18.2% versus 5.9%, P = 0.0009) and NNRTI mutations (11.7% versus 2.8%, P = 0.004) in the later time period. PI TDR remained unchanged.
  
  
  CONCLUSIONS
  Baseline GRT increased dramatically since 2002, but remains below 100%. The prevalence of overall TDR tripled due to increases in NRTI and NNRTI mutations. These findings highlight the value of routine baseline GRT for TDR surveillance and patient care.
authors: Ontario HIV Treatment Network, Toronto, Canada. aburchell@ohtn.on.ca
authors: Ann N
authors: AN
authors: Burchell
authors: Ahmed M
authors: AM
authors: Bayoumi
authors: Sean B
authors: SB
authors: Rourke
authors: Carol
authors: C
authors: Major
authors: Sandra
authors: S
authors: Gardner
authors: Paul
authors: P
authors: Sandstrom
authors: Anita
authors: A
authors: Rachlis
authors: Darien
authors: D
authors: Taylor
authors: Tony
authors: T
authors: Mazzulli
authors: Mark
authors: M
authors: Fisher
authors: James
authors: J
authors: Brooks
mesh_terms: D000328:Adult; D019380:Anti-HIV Agents / Q000494:pharmacology*; D015331:Cohort Studies; D024882:Drug Resistance, Viral; D005260:Female; D006678:HIV / Q000187:drug effects* / Q000235:genetics* / Q000302:isolation & purification; D015658:HIV Infections / Q000453:epidemiology / Q000635:transmission* / Q000821:virology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009864:Ontario / Q000453:epidemiology; D015995:Prevalence
chemical_list: D019380:Anti-HIV Agents