As researchers learn more about the importance of bringing viral load as low as possible for as long as possible, data about the magnitude and duration of viral load responses becomes especially important. For patients on therapy that includes indinavir, emergence of resistance is generally slower in patients who get their viral load below 500 copies/mL. This study examined results in 106 patients from several early indinavir studies, including monotherapy studies, who got to below 500 copies by Week 24 of their studies, and who stayed there for at least 12 weeks. The study then looked for patients who "failed", or rose back above the limits of detection, and whose virus had mutations associated with indinavir resistance.

Not surprisingly, after 108 weeks, patients who started on monotherapy had a greater chance of treatment failure due to resistance than those who started on triple therapy with indinavir and AZT/3TC (20% vs. 12% respectively). This is consistent with other studies presented here that emphasize how criticial is is to begin combination antiretroviral therapy all at the same time, rather than adding new drugs to existing regimens, or adding one drug after other over time.