title: Prevalence of HIV-1 drug resistance in treated patients: a French nationwide study.
abstract: BACKGROUND
  Surveillance of HIV-1 drug resistance in antiretroviral-treated patients is important from the public health perspective of the spread of resistance and to evaluate the proportion of patients for whom new drugs are needed.
  
  
  METHODS
  Patients were consecutively included in 28 centers in France and 1 center in Switzerland if they had a viral load measurement performed in June 2004, with a result >or=1,000 copies/mL. Reverse transcriptase, protease, and gp41 genes were sequenced, and resistance mutations were reported as listed on the Web site ( www.iasusa.org). The genotypic resistance results were interpreted by the Agence Nationale de Recherches sur le SIDA et les Hepatites Virales (ANRS) and Stanford algorithms.
  
  
  RESULTS
  The 498 patients included had been exposed to 9 (interquartile ratio [IQR]: 6 to 12) antiretroviral drugs. Patients' viruses harbored 4 nucleoside reverse transcriptase inhibitor (IQR: 1 to 6) and 4 protease inhibitor (PI; IQR: 2 to 8) resistance mutations, whereas 44% had at least 1 nonnucleoside reverse transcriptase inhibitor resistance mutation. The frequency of resistance to at least 1 drug was 88% with the ANRS algorithm and 83% with the Stanford algorithm. The frequencies of complete resistance to 1, 2, and 3 classes of drugs were 37%, 15%, and 4%, respectively, with the ANRS algorithm and 27%, 23%, and 24%, respectively, with the Stanford algorithm. The most important differences between algorithms were for PIs. Using the ANRS algorithm and extrapolation on the whole French database, 19% of all treated patients could contribute to the spread of resistance and 4% had complete resistance to 2 classes of antiretroviral drugs.
  
  
  CONCLUSIONS
  The observed patterns of resistance are linked to a long-lasting history of antiretroviral therapy. The frequency of multiresistance can vary according to the interpretation systems.
authors.affiliation: INSERM, Unité Mixte de Recherche (UMR) S 720, Université Pierre et Marie Curie-Paris 6, Paris, France.
authors.forename: Dominique
authors.initials: D
authors.lastname: Costagliola
authors.forename: Diane
authors.initials: D
authors.lastname: Descamps
authors.forename: Lambert
authors.initials: L
authors.lastname: Assoumou
authors.forename: Laurence
authors.initials: L
authors.lastname: Morand-Joubert
authors.forename: Anne-Geneviève
authors.initials: AG
authors.lastname: Marcelin
authors.forename: Véronique
authors.initials: V
authors.lastname: Brodard
authors.forename: Constance
authors.initials: C
authors.lastname: Delaugerre
authors.forename: Vincent
authors.initials: V
authors.lastname: Mackiewicz
authors.forename: Annick
authors.initials: A
authors.lastname: Ruffault
authors.forename: Jacques
authors.initials: J
authors.lastname: Izopet
authors.forename: Jean-Christophe
authors.initials: JC
authors.lastname: Plantier
authors.forename: Catherine
authors.initials: C
authors.lastname: Tamalet
authors.forename: Sabine
authors.initials: S
authors.lastname: Yerly
authors.forename: Souhaha
authors.initials: S
authors.lastname: Saidi
authors.forename: Françoise
authors.initials: F
authors.lastname: Brun-Vezinet
authors.forename: Bernard
authors.initials: B
authors.lastname: Masquelier
mesh_terms: D000328:Adult; D019380:Anti-HIV Agents / Q000494:pharmacology*; D024921:Drug Resistance, Multiple, Viral; D005260:Female; D005602:France / Q000453:epidemiology; D015658:HIV Infections / Q000188:drug therapy* / Q000453:epidemiology / Q000821:virology*; D015497:HIV-1 / Q000187:drug effects*; D006801:Humans; D008297:Male; D008875:Middle Aged; D015995:Prevalence
chemical_list: D019380:Anti-HIV Agents