title: Change over time in incidence of ganciclovir resistance in patients with cytomegalovirus retinitis.
abstract: BACKGROUND
  In the mid-1990s, the incidence of cytomegalovirus (CMV) resistance to ganciclovir was estimated to be approximately 25% by 1 year after diagnosis of retinitis in patients with acquired immunodeficiency syndrome.
  
  
  METHODS
  Two hundred fifty-seven patients with CMV retinitis were enrolled in a prospective observational study during 1993-2003 and were treated with ganciclovir. Demographic characteristics and data on CMV disease, antiretroviral therapy, and ganciclovir resistance were recorded for all patients. Human immunodeficiency virus (HIV) load and CMV load were measured for patients enrolled in 1996 or later. Kaplan-Meier and Cox proportional hazards regression methods were used to examine incidence of resistance.
  
  
  RESULTS
  The 2-year incidence of resistance was 28% among patients enrolled before 1996 and 9% among those enrolled in or after 1996 (P=.001). All cases of resistance occurred among patients with CD4+ T cell counts <50 cells/microL, and positive CMV culture results at baseline were associated with a approximately 4-fold increase in resistance. Among patients whose CMV and HIV loads were measured, a detectable CMV load at baseline and during follow-up was associated with increased risk of resistance, but a detectable HIV load was not.
  
  
  CONCLUSIONS
  Rates of resistance have decreased from the high levels seen in the pre-HAART era. Better control of CMV replication may have contributed to this decrease.
authors.affiliation: Department of Epidemiology, The Johns Hopkins University Bloomberg School of Public Health, Baltimore, MD, USA. bmartin@jhsph.edu
authors.forename: Barbara K
authors.initials: BK
authors.lastname: Martin
authors.forename: Michelle O
authors.initials: MO
authors.lastname: Ricks
authors.forename: Michael S
authors.initials: MS
authors.lastname: Forman
authors.forename: Douglas A
authors.initials: DA
authors.lastname: Jabs
mesh_terms: D017088:AIDS-Related Opportunistic Infections / Q000175:diagnosis / Q000188:drug therapy / Q000453:epidemiology*; D000328:Adult; D017677:Age Distribution; D023241:Antiretroviral Therapy, Highly Active / Q000379:methods; D003587:Cytomegalovirus / Q000187:drug effects* / Q000302:isolation & purification; D017726:Cytomegalovirus Retinitis / Q000175:diagnosis / Q000188:drug therapy / Q000453:epidemiology*; D024882:Drug Resistance, Viral; D005260:Female; D005500:Follow-Up Studies; D015774:Ganciclovir / Q000494:pharmacology* / Q000627:therapeutic use; D006801:Humans; D015994:Incidence; D008297:Male; D008826:Microbial Sensitivity Tests; D016012:Poisson Distribution; D011336:Probability; D016016:Proportional Hazards Models; D011446:Prospective Studies; D018570:Risk Assessment; D017678:Sex Distribution; D016019:Survival Analysis
chemical_list: D015774:Ganciclovir