Factors associated with the successful modification of antiretroviral therapy

Objectives: To assess the characteristics of medication regimen modificatio n and the influence of a commercial genotypic resistance assay on the short -term (3-12 weeks) viral load response (greater than or equal to 0.5 log re duction) in HIV-1-infected patients extensively treated with antiretroviral therapy (ART). Methods: A nested cohort study was performed in two clinics from the HIV Ou tpatient Study of 96 persons with a HIV-1 viral load of 10(4) log copies/ml or greater taking at least two antiretroviral medications. Results: Successful modification was associated with adding at least two ne w medications [relative risk (RR), 1.5; 95% confidence interval (CI), 1.1-2 .2], adding a drug from a previously unused class of agents (RR, 2.0; Cl, 1 .4-2.9), the initiation of a nonnucleoside reverse transcriptase inhibitor (NNRTI) (RR, 1.7; Cl, 1.2-2.4), but not substituting a protease inhibitor o r the use of a commercial genotypic resistance assay. Conclusion: Incorporating a drug from a previously unused class or changing at least two new medications, but, within the confines of this study, not using a commercial genotypic resistance assay, was associated with the succ essful modification of ART as measured by a reduction in viral load. (C) 20 00 Lippincott Williams Wilkins.