STRATEGY-PI is a @ week , international , multicentre , randomised , open-label , phase @b trial in which HIV-infected adults with a plasma HIV-@ RNA viral load of less than @ copies per mL for at least @ months who were taking a ritonavir-boosted protease inhibitor with emtricitabine plus tenofovir were randomly assigned ( @:@ ) either to switch to coformulated elvitegravir , cobicistat , emtricitabine , and tenofovir or to continue on their existing regimen .