Factors significantly associated with a switch to ATV without ritonavir rather than a switch to ATV with ritonavir were female sex, asymptomatic HIV infection (according to the CDC classification), higher CD4 cells nadir, high number of previous lines of treatment, prior treatment with 3 NRTI, longer time with undetectable plasma viral load, higher CD4 cell count and more dyslipidemia as the reason for the switch. Here, CD4 is linked to HIV infectious disease.