[Simplification to lamivudine, zidovudine, and abacavir therapy: impact on adherence, clinical outcome, and economic issues]

Abstract

Objectives: To analyze the influence on adherence and clinical outcome of the replacement of a previous antiretroviral therapy to a simplified approach using zidovudine, lamivudine, and abacavir (Trizivir) and to assess its economic impact.

Methods: A retrospective study of 75 pretreated, HIV-infected adult patients who received Trizivir from May 2001 to December 2002. Adherence was assessed by dispensation records or medication counting, CD4 lymphocyte counts, and viral load before and six months after medication change was analyzed; finally, the cost of each therapy was assessed in order to calculate the economic impact of medication change.

Results: Mean adherence significantly increased a 2.5% after medication change; 16 more patients reached optimal adherence, with an NNT (number of patients requiring therapy change in order to obtain one more adherent) of 4.7. The number of patients with undetectable viral load remained almost similar, and mean CD4 cell counts stayed above 500 cells/mm3 in both periods of time. A great variability in incremental costs was seen, due to the varying costs of the previous treatments, and the influence of five intensification therapies using Trizivir. However, when only simplification regimens were analyzed such variability was reduced, and even became favorable in selected cases.

Conclusions: Changing to a simplification therapy using Trizivir resulted in improved adherence, similar clinical outcomes, and a varying economic impact depending on previous antiretroviral therapy costs.