title: Triple-class antiretroviral drug resistance: risk and predictors among HIV-1-infected patients.
abstract: BACKGROUND
  HIV-1 triple-class antiretroviral drug resistance (TC-DR) may substantially limit therapeutic options and compromise clinical outcomes.
  
  
  OBJECTIVE
  To estimate TC-DR prevalence and incidence, and identify risk factors for TC-DR acquisition.
  
  
  METHODS
  We identified patients in the University of North Carolina HIV Cohort Study with TC-DR HIV-1 variants. Nucleos(t)ide reverse transcriptase inhibitor (NRTI), non-nucleoside reverse transcriptase inhibitor (NNRTI), and major protease inhibitor (PI) mutations, were based on the International AIDS Society - USA guidelines. Prevalence was estimated with the exact binomial distribution, incidence with the exact Poisson distribution, and multivariable analyses were performed using logistic regression.
  
  
  RESULTS
  Of 1587 patients, half initiated therapy with HAART (N = 789), 20% (N = 320) with non-HAART combination therapy, and 30% (N = 478) with one NRTI. The median time on therapy was 5.7 years [interquartile range (IQR) 2.9, 8.6], the median number of previous antiretroviral agents was six (IQR 4, 8), and 47% (N = 752) were exposed to at least one NRTI, NNRTI and PI. Assuming patients without genotypes did not harbor TC-DR virus, the prevalence of TC-DR among all antiretroviral-experienced patients was 8% [95% confidence interval (CI) 6%, 9%]. The prevalence was 3% (95% CI 2%, 4%) and 12% (95% CI 10%, 15%) among patients treated initially with HAART and non-HAART, respectively. The number of antiretroviral agents received and initiating therapy with non-HAART or an unboosted PI, increased TC-DR risk in multivariable analyses.
  
  
  CONCLUSIONS
  The majority of patients with TC-DR have extensive antiretroviral exposure, particularly to non-HAART regimens, whereas HAART initiators are at low risk of acquiring TC-DR during a median of 4 years of follow-up.
authors.affiliation: Division of Infectious Diseases, School of Medicine, the University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA. napravs@med.unc.edu
authors.forename: Sonia
authors.initials: S
authors.lastname: Napravnik
authors.forename: Jessica R
authors.initials: JR
authors.lastname: Keys
authors.forename: E Byrd
authors.initials: EB
authors.lastname: Quinlivan
authors.forename: David A
authors.initials: DA
authors.lastname: Wohl
authors.forename: Oksana V
authors.initials: OV
authors.lastname: Mikeal
authors.forename: Joseph J
authors.initials: JJ
authors.lastname: Eron
mesh_terms: D000328:Adult; D019380:Anti-HIV Agents / Q000008:administration & dosage; D023241:Antiretroviral Therapy, Highly Active; D018791:CD4 Lymphocyte Count; D004334:Drug Administration Schedule; D024921:Drug Resistance, Multiple, Viral / Q000235:genetics; D005260:Female; D005500:Follow-Up Studies; D005838:Genotype; D015658:HIV Infections / Q000188:drug therapy* / Q000276:immunology / Q000821:virology; D015497:HIV-1 / Q000187:drug effects* / Q000235:genetics; D006801:Humans; D008297:Male; D008875:Middle Aged; D009154:Mutation; D012307:Risk Factors; D019562:Viral Load
chemical_list: D019380:Anti-HIV Agents