Study Objective. To evaluate the efficacy, safety, and lipid‐lowering effects after switching from a non‐atazanavir‐containing, protease inhibitor‐based highly active antiretroviral therapy (HAART) to atazanavir‐ritonavir‐based HAART in patients infected with human immunodeficiency virus (HIV).

Design. Multicenter, noncontrolled, retrospective study.

Setting. Three tertiary teaching hospitals.

Patients. Thirty‐six patients with HIV infection, aged 18 years or older, who were receiving non‐atazanavir‐containing, protease inhibitor‐based HAART that was switched to atazanavir 300 mg‐ritonavir 100 mg‐based HAART without changes in nucleoside reverse transcriptase inhibitors and confounders known to alter serum lipid levels.

Measurements and Main Results. Lipid profiles measured 4 weeks‐6 months before the switch, as well as follow‐up lipid profiles measured 4 weeks‐6 months after receiving the new HAART regimen, were evaluated. The switch resulted in the following changes in lipid levels: total cholesterol−9% (p=0.002), low‐density lipoprotein cholesterol−13% (p<0.001), high‐density lipoprotein cholesterol (HDL)−2% (p=0.431), triglycerides−23% (p=0.007), non‐HDL−11% (p=0.002), total cholesterol:HDL ratio−10% (p=0.004), and triglyceride:HDL ratio−24% (p=0.019). A subgroup analysis was conducted on the lipid profiles of nine patients who still met the strict inclusion and exclusion criteria up to 9 months after the switch; it showed that the reductions in their lipid profiles were sustained. In addition, 33% more patients achieved their National Cholesterol Education Panel (NCEP) Adult Treatment Panel (ATP) III cholesterol goals. No significant changes were noted in median (interquartile range) CD4⁺ counts (372 [236–551] and 361 [217–464] cells/mm³, p=0.118) or in number of patients with undetectable HIV viral loads ([defined as < 50 copies/ml] 32/36 and 31/36 patients, p>0.05) between baseline and after the switch, respectively.

Conclusion. Switching to an atazanavir‐ritonavir‐based HAART regimen was associated with significant improvement in lipid profiles, similar to those seen in clinical trials, without compromising safety or viral and immunologic control. In addition, more patients were able to achieve their NCEP ATP III goals.