title: Treatment outcomes of first-line antiretroviral therapy in HIV-1-positive patients in Serbia.
abstract: BACKGROUND
  Access to combination antiretroviral treatment (cART) and toxicity profiles of antiretroviral medications have significantly improved during the last three decades. In order to optimise treatment outcomes, achieve favourable virological suppression and immunological status, balanced with potential adverse effects of cART, it is considered beneficial to maintain first-line antiretroviral treatment for as long as possible. However, the Republic of Serbia, as a resource-limited setting, often experiences interruptions to drug supplies. Data are very limited in Serbia concerning the initial antiretroviral regimens prescribed and the reasons for treatment changes.
  
  
  OBJECTIVE
  The aim of this study was to determine the most frequently prescribed antiretroviral drugs within first-line cART regimens in drug-naïve patients in Serbia and the reasons for switching drugs.
  
  
  METHODS
  All HIV-infected individuals who started cART at the HIV/AIDS Center of Infectious and Tropical Diseases, Clinical Centre of Serbia, from 1 January 2004 until 1 July 2014 were included. A cohort of 339 patients were retrospectively analysed to review their initial treatment regimens. All analyses were performed using the SPSS statistical package version 11.0. Descriptive measurements and Kaplan-Meier survival curves were used.
  
  
  RESULTS
  The most frequently prescribed nucleoside reverse transcriptase inhibitor (NRTI) backbones in the cART regiment were fixed combinations of abacavir and lamivudine (n=181, 53.3%) and of zidovudine and lamivudine (n=103, 30.5%). Efavirenz was the most commonly prescribed 'third' drug (n=254, 75%). Where given, reasons for switching initial cART were shortage of antiretroviral drugs (e.g. out of stock, n=53, 37.6%), toxicity (n=49, 34.3%), physician choice (n=21, 14.6%), resistance (n=15, 10.6%), and patient choice (n=4, 2.9%). Mean duration of first-line cART was 20±17 months.
  
  
  CONCLUSIONS
  The most frequently prescribed initial cART regimen in Serbia is not the preferred first choice, but an alternative option according to the international antiretroviral treatment guidelines. Duration of first-line cART is short and a switch to second-line cART is often made due to a shortage of antiretroviral medications and the more severe side effects resulting from the use of older drugs.
authors.affiliation: Department of Pharmacology, Clinical Pharmacology and Toxicology, School of Medicine , University of Belgrade , Belgrade , Serbia.
authors.forename: Jovana
authors.initials: J
authors.lastname: Kušić
authors.affiliation: School of Medicine , University of Belgrade , Belgrade , Serbia.
authors.forename: Milana
authors.initials: M
authors.lastname: Mladenović
authors.affiliation: Department of Pharmacology, Clinical Pharmacology and Toxicology, School of Medicine , University of Belgrade , Belgrade , Serbia.
authors.forename: Božana
authors.initials: B
authors.lastname: Dimitrijević
authors.affiliation: School of Medicine , University of Belgrade , Belgrade , Serbia.
authors.forename: Branka
authors.initials: B
authors.lastname: Aleksić
authors.affiliation: School of Medicine , University of Belgrade , Belgrade , Serbia.
authors.forename: Simon
authors.initials: S
authors.lastname: Zec
authors.affiliation: Infectious and Tropical Diseases Hospital, School of Medicine , University of Belgrade , Belgrade , Serbia.
authors.forename: Djordje
authors.initials: D
authors.lastname: Jevtović
authors.affiliation: Department of Pharmacology, Clinical Pharmacology and Toxicology, School of Medicine , University of Belgrade , Belgrade , Serbia.
authors.forename: Gordana
authors.initials: G
authors.lastname: Dragović Lukić
keywords: HIV/AIDS; drug shortages; first-line cART; switch