title: Triple class experience after initiation of combination antiretroviral treatment in Australia: survival and projections.
abstract: BACKGROUND
  Patients who have become triple class experienced (TCE) are at a high risk of exhausting available treatment options. This study aims to investigate factors associated with becoming TCE and to explore the effect of becoming TCE on survival. We also project the prevalence of TCE in Australia to 2012.
  
  
  METHODS
  Patients were defined as TCE when they stopped a combination antiretroviral treatment (cART) that introduced the third of the three major antiretroviral classes. Cox proportional hazards models were used to investigate factors associated with TCE and the effect of TCE on survival. To project TCE prevalence, we used predicted rates of TCE by fitting a Poisson regression model, together with the estimated number of patients who started cART in each year in Australia, assuming a mortality rate of 1.5 per 100 person-years.
  
  
  RESULTS
  Of the 1498 eligible patients, 526 became TCE. Independent predictors of a higher risk of TCE included current CD4 counts below 200cellsμL(-1) and earlier calendar periods. No significant difference in survival was observed between those who were TCE and those who were not yet TCE. An increasing number of patients are using cART in Australia and if current trends continue, the number of patients who are TCE is estimated to increase from 2800 in 2003 to 5000 in 2012.
  
  
  CONCLUSIONS
  Our results suggest that the prevalence of TCE in Australia is estimated to plateau after 2003. However, as an increasing number of patients are becoming TCE, it is necessary to develop new drugs that come from new classes or do not have overlapping resistance.
authors.affiliation: National Centre in HIV Epidemiology and Clinical Research, University of New South Wales, Sydney, NSW 2052, Australia. sadaf.marashipour@doh.health.nsw.gov.au
authors.forename: Sadaf Marashi
authors.initials: SM
authors.lastname: Pour
authors.forename: Ian
authors.initials: I
authors.lastname: Woolley
authors.forename: Peter
authors.initials: P
authors.lastname: Canavan
authors.forename: John
authors.initials: J
authors.lastname: Chuah
authors.forename: Darren B
authors.initials: DB
authors.lastname: Russell
authors.forename: Matthew
authors.initials: M
authors.lastname: Law
authors.forename: Kathy
authors.initials: K
authors.lastname: Petoumenos
mesh_terms: D000328:Adult; D023241:Antiretroviral Therapy, Highly Active / Q000706:statistics & numerical data / Q000639:trends*; D001315:Australia; D015331:Cohort Studies; D005260:Female; D005544:Forecasting; D015658:HIV Infections / Q000188:drug therapy* / Q000401:mortality*; D006801:Humans; D008297:Male; D008875:Middle Aged; D016016:Proportional Hazards Models; D016019:Survival Analysis; D014600:Utilization Review / Q000706:statistics & numerical data