Virologic efficacy of boosted double versus boosted single protease inhibitor therapy

AIDS. 2007 Jul 31;21(12):1547-54. doi: 10.1097/QAD.0b013e32825a69a8.


Objective: Although regimens containing two protease inhibitor (PI) together with ritonavir boosting are used with the aim of improving virologic response to salvage therapy, there is little evidence to support or reject this approach. We compared the probability of attaining an undetectable HIV RNA level after using either boosted double or boosted single PI regimens.

Design: Retrospective clinical cohort.

Methods: PI-experienced subjects in a Northern California-based database who initiated either a boosted single or boosted double PI salvage therapy regimen were analysed. Traditional multivariable regression and marginal structural model analyses were used to compare the effects of the two regimens on virologic suppression 12-36 weeks after initiation of salvage therapy, controlling for confounding by baseline HIV RNA level, CD4 lymphocyte count, treatment history, drug resistance, and multiple characteristics of the salvage regimen.

Results: Fifty-one percent of boosted single PI regimens (n=805) and 51.6% of boosted double PI regimens (n=183) achieved a plasma HIV RNA level of <75 copies/ml at week 12-36. In models including multiple potentially confounding variables, estimates of the relative odds of suppression on boosted double versus boosted single PI regimens ranged from 1.17 (95% CI, 0.54-2.55) to 1.33 (95% CI, 0.82-2.14).

Conclusions: We were not able to reject the null hypothesis that boosted double versus boosted single PI regimens, resulted in equivalent probabilities of virologic success.

Publication types

  • Multicenter Study
  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Antiretroviral Therapy, Highly Active / methods
  • CD4 Lymphocyte Count
  • Drug Evaluation
  • Drug Resistance, Viral
  • HIV Infections / drug therapy*
  • HIV Infections / immunology
  • HIV Infections / virology
  • HIV Protease Inhibitors / therapeutic use*
  • HIV-1 / genetics
  • HIV-1 / isolation & purification*
  • Humans
  • RNA, Viral / blood
  • Retrospective Studies
  • Salvage Therapy / methods*
  • Treatment Outcome
  • Viral Load


  • HIV Protease Inhibitors
  • RNA, Viral