The researchers assigned patients at random to take either regimen A (stavudine, didanosine, and efavirenz) or regimen B (zidovudine, lamivudine, and nelfinavir) until the treatment failed or to alternate between regimen A and B every 3 months. They then compared how long patients in each group avoided treatment failure. The researchers defined treatment failure as viral load rising above 400 copies/mL after successfully being decreased below 400 copies/mL. They also looked at CD4 cell counts, side effects, drug resistance, how closely people followed the drug regimens, and quality of life.