title: The frequency and reasons for antiretroviral switching with specific antiretroviral associations: the SWITCH study.
abstract: BACKGROUND
  We investigated the reasons for switching antiretroviral regimens, an issue rarely addressed in cohort studies.
  
  
  METHODS
  An observed toxicity switch rate (OTSR) was calculated by Poisson regression using the number of days individuals received each individual antiretroviral drug.
  
  
  RESULTS
  Of 3333 individuals receiving HAART, a total of 14% of regimens were switched, the majority occurring after 6 months of therapy. Toxicity was the major reason for switching (61%) and there were no major statistically significant differences in OTSR between the protease inhibitor (OTSR 26.4, 95% CI 18.3-37) and non-nucleoside reverse transcriptase inhibitor (OTSR 22.2, 95% CI 13.6-34.4) based regimes. For individual antiretrovirals, stavudine and zidovudine had significantly higher "switch" scores than all other drugs.
  
  
  CONCLUSIONS
  There were no differences between the major HAART classes in OTSR. We suggest that newer antiretrovirals will require differentiation in terms of longer-term toxicity, as this is the major reason for switching.
authors.affiliation: St. Stephen's Centre, Chelsea and Westminster Hospital Trust, United Kingdom.
authors.forename: I
authors.initials: I
authors.lastname: Davidson
authors.forename: H
authors.initials: H
authors.lastname: Beardsell
authors.forename: B
authors.initials: B
authors.lastname: Smith
authors.forename: S
authors.initials: S
authors.lastname: Mandalia
authors.forename: M
authors.initials: M
authors.lastname: Bower
authors.forename: B
authors.initials: B
authors.lastname: Gazzard
authors.forename: M
authors.initials: M
authors.lastname: Nelson
authors.forename: J
authors.initials: J
authors.lastname: Stebbing
mesh_terms: D019380:Anti-HIV Agents / Q000008:administration & dosage* / Q000009:adverse effects*; D023241:Antiretroviral Therapy, Highly Active / Q000379:methods*; D015331:Cohort Studies; D015658:HIV Infections / Q000188:drug therapy*; D006801:Humans; D016312:Treatment Refusal / Q000706:statistics & numerical data
chemical_list: D019380:Anti-HIV Agents