title: Prevalence and risk factors for etravirine resistance among patients failing on non-nucleoside reverse transcriptase inhibitors.
abstract: BACKGROUND
  Prevalence and factors associated with etravirine (EW) resistance mutations among patients failing on first-generation non-nucleoside reverse transcriptase inhibitors (NNRTI) merit investigation.
  
  
  METHODS
  The study comprised an analysis of all sequential patients attending the Institute of Infectious Diseases (Brescia, northern Italy) who performed a genotypic resistance testing (GRT) after > or =3 months of a stable NNRTI-based regimen between 2001 and 2006. Multivariable ordinal logistic regression analysis was performed to assess predictors of ETV resistance mutations.
  
  
  RESULTS
  Out of 248 strains, 153 (61.7%) harboured > or =1 ETV resistance mutations. In particular, 88 (35.5%), 53 (21.4%) and 12 (4.8%) harboured one, two and three mutations, respectively. The most frequent mutations were G190A (230%), Y181C (23%) and K101E (14.1%). Use of nevirapine (odds ratio [OR] 2.73; 95% confidence level [CI] 1.62-4.62; P<0.001) and a longer time frame between first HIV RNA >500 copies/ml and GRT (per month, OR 1.05; 95% CI 1.01-1.09; P=0.012) were associated with a greater number of ETV resistance mutations. Conversely, higher CD4+ T-cell counts at nadir (per 100 cells/mm3, OR 0.81; 95% CI 0.67-0.98; P=0.029) and use of lamivudine/emtricitabine (OR 0.57; 95% CI 0.37-0.87; P=0.009) were protective. Accumulation of ETV resistance-associated mutations was demonstrated by sequential GRT in 4/35 patients (all treated with nevirapine).
  
  
  CONCLUSIONS
  Mutations associated with ETW resistance were common among patients failing on NNRTI, but prevalence of viral strains harbouring three mutations was low. Use of efavirenz and co-administration of lamivudine reduced the risk of ETW resistance. The continued use of the current NNRTI in a failing regimen may select for additional resistant variants.
authors.affiliation: Clinic for Infectious Diseases and Tropical Medicine, University of Brescia, Brescia, Italy. g.lapadula@infettivibrescia.it
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Lapadula
authors.forename: Alessandra
authors.initials: A
authors.lastname: Calabresi
authors.forename: Filippo
authors.initials: F
authors.lastname: Castelnuovo
authors.forename: Silvia
authors.initials: S
authors.lastname: Costarelli
authors.forename: Eugenia
authors.initials: E
authors.lastname: Quiros-Roldan
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Paraninfo
authors.forename: Francesca
authors.initials: F
authors.lastname: Ceresoli
authors.forename: Franco
authors.initials: F
authors.lastname: Gargiulo
authors.forename: Nino
authors.initials: N
authors.lastname: Manca
authors.forename: Giampiero
authors.initials: G
authors.lastname: Carosi
authors.forename: Carlo
authors.initials: C
authors.lastname: Torti
mesh_terms: D000328:Adult; D019380:Anti-HIV Agents / Q000494:pharmacology / Q000627:therapeutic use; D018791:CD4 Lymphocyte Count; D024882:Drug Resistance, Viral / Q000235:genetics*; D005260:Female; D015658:HIV Infections / Q000188:drug therapy* / Q000453:epidemiology / Q000821:virology; D015497:HIV-1 / Q000145:classification / Q000187:drug effects* / Q000235:genetics; D006801:Humans; D007558:Italy / Q000453:epidemiology; D016015:Logistic Models; D008297:Male; D008826:Microbial Sensitivity Tests / Q000379:methods; D009154:Mutation; D019829:Nevirapine / Q000494:pharmacology / Q000627:therapeutic use*; D009570:Nitriles; D015995:Prevalence; D011724:Pyridazines / Q000494:pharmacology*; D011743:Pyrimidines; D012367:RNA, Viral / Q000097:blood; D018894:Reverse Transcriptase Inhibitors / Q000494:pharmacology / Q000627:therapeutic use; D012307:Risk Factors; D017211:Treatment Failure
chemical_list: D019380:Anti-HIV Agents; D009570:Nitriles; D011724:Pyridazines; D011743:Pyrimidines; D012367:RNA, Viral; D018894:Reverse Transcriptase Inhibitors; C451734:etravirine; D019829:Nevirapine