Impact of genotypic resistance testing on physician selection of antiretroviral therapy

Objectives: To determine the impact of genotypic resistance testing on phys ician selection of antiretroviral therapy. Study Design/Methods: This was a prospective, observational study. A single genotypic resistance test was done when patients failed highly active anti retroviral therapy. The antiretroviral regimen predicted at the time the ge notypic resistance assay was done was compared with the regimen that was ul timately selected after review of resistance testing results. Results: In the vast majority of cases (83%), the regimen that the physicia n selected after resistance testing was different from the predicted regime n. In 54% of cases, these changes involved changing more than two antiretro viral agents, and in22%, one agent was changed. In 1% of cases, all medicat ions were discontinued, and in 6%, the physician ultimately decided not to change the baseline regimen, Although patients were screened for nonadheren ce to their medication regimen, 11% had no detectable resistance mutations. Conclusions: Access to genotypic resistance testing has a significant impac t on physician selection of antiretroviral therapy.