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The Body Covers: The 2nd International AIDS Society Conference on HIV Pathogenesis and Treatment
Switch Study Shows Improved Suppression and Adherence Rates With Once-Daily Efavirenz-Based Regimens Vs. Most PI-Based Regimens

July 14, 2003

A note from The field of medicine is constantly evolving. As a result, parts of this article may be outdated. Please keep this in mind, and be sure to visit other parts of our site for more recent information!

A few years ago, a pilot study was conducted (the Montana study) which tested the efficacy of the combination of three antivirals all given once-daily: ddI (didanosine, Videx), efavirenz (EFV, Sustiva) and FTC (emtricitabine, Emtriva), an antiviral recently approved in the U.S. that is similar to 3TC (lamivudine, Epivir). The combination was shown to be very effective over time, with a high number of people maintaining viral control. Following that pilot, this study was conducted. The design offered to randomize those who were already virologically suppressed on a regimen of two NRTIs plus a protease inhibitor (PI) (less than 400 copies/mL for at least six months) to either stay on their combination or change to a regimen of ddI (now given as the newer Videx-EC capsule), FTC and efavirenz -- all given once a day (here referred to as the QD arm).

The researchers randomized 355 people to the two arms of the study for the next 48 weeks and reported the results at this conference. To be eligible, all participants had to be naive to the NNRTI class. Most were on either nelfinavir (NFV, Viracept) or indinavir (IDV, Crixivan). The primary endpoint was to assess the ability of either regimen to maintain suppression. The overall results showed that -- using the standard intent-to-treat analysis at week 48 using a 400 c/mL cutoff -- 88 percent of those on the PI and 90 percent on the QD arm were successful.

Excluding those who dropped out of the study prior to week 48 and were still on treatment at week 48, about 95 percent in both arms had a viral load less than 400 c/mL. However, using a 50-copy assay instead, they reported that 95 percent were suppressed on the QD arm, but only 87 percent were suppressed on the PI arm, a difference which achieved statistical significance (p<.01).

Supporting these findings was the fact that adherence rates were better in the QD arm; 95 percent of patients on QD versus 86 percent on the PI had high levels of adherence noted with their regimen. As of week 48, about 15 percent in both arms had discontinued participation -- mostly due to adverse events prior to this time point. The researchers also noted an improvement in HDL cholesterol in the QD arm, as about twice as many patients had an elevation in this protective lipid measurement.

These results support several other studies that randomized people to either stay on a PI or switch to a regimen containing two NRTIs plus efavirenz. In all of the prior results, there were improved suppression rates noted over time in those switching to efavirenz, even though the studies all selected people who were successful on their PI. These studies continue to show that a regimen of two NRTIs plus efavirenz remains successful, almost regardless of which two NRTIs are combined with the efavirenz, even in those with successful viral control on PI-based regimens.

As most of these studies were done a few years ago, and included regimens that did not contain either a boosted PI or atazanavir (ATV, Reyataz), these results can be seen as guiding primarily those on PIs other than these, since the potency and success of these newer approaches may alter how much of a difference we would see in a switch. Nevertheless, even if success rates are similar in those on boosted PIs, a switch to three meds all taken once-daily may offer convenience advantages, and for that reason may still be attractive to consider even for those doing well virologically.

A note from The field of medicine is constantly evolving. As a result, parts of this article may be outdated. Please keep this in mind, and be sure to visit other parts of our site for more recent information!

See Also
6 Reasons Why People Skip Their HIV Meds
Word on the Street: Advice on Adhering to HIV Treatment
More HIV Treatment Adherence Research

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