In an era of ever-increasing healthcare costs, knowledge of cost effectiveness is critical for US physicians, policymakers, and payers alike. Results from a cost-effectiveness study undertaken by investigators from PHAR, LLC and Bristol-Myers Squibb was presented at the 10th International Congress on Drug Therapy in HIV Infection. The model found that patients using atazanavir with ritonavir experience AIDS diagnoses, opportunistic infections, coronary heart disease events, and diarrhea episodes less often than patients using lopinavir in combination with ritonavir.