Background: Incomplete adherence is the main cause of antiretroviral therapy failure during initial combination antiretroviral therapy (cART). A switch to a protease inhibitor-sparing cART may be useful when a patient does not tolerate a first protease inhibitor-containing cART regimen.
Methods: To compare the biological and clinical outcomes of patients in whom a first protease inhibitor-containing cART regimen failed to control viral replication and whose treatment was switched to cART containing efavirenz, nevirapine, or abacavir, we studied 1440 patients from the French Hospital Database on HIV whose treatment was changed from a first protease inhibitor-containing cART to a 3-drug regimen with either efavirenz, nevirapine, or abacavir while their plasma viral load was detectable.
Results: Kaplan-Meier 12-month probabilities of virological suppression were 73.6%, 53.9%, and 66.1% among patients whose treatment was switched to efavirenz-cART, nevirapine-cART, and abacavir-cART, respectively. Factors associated with a lower likelihood of virological suppression were antiretroviral exposure before the first cART, higher plasma viral load values at the treatment switch, a stavudine-lamivudine backbone after the switch (instead of a zidovudine-lamivudine backbone), and a switch to nevirapine (adjusted hazard ratio, 0.63 [95% CI, 0.54-0.74], compared with efavirenz) or abacavir (adjusted hazard ratio, 0.84 [95% CI, 0.68-1.04] compared with efavirenz). There was no difference among the 3 groups with regard to immunological gain (>50 CD4+ T cells/mm3) or clinical outcome.
Conclusion: When virological rebound occurs from receipt of protease inhibitor-containing cART, virological suppression can be obtained after a switch to a protease inhibitor-free cART--efavirenz-cART yielding the highest rate of virological suppression.