Evaluation of Atazanavir Substitution Intervention (EASI) Study

This will be a single arm observational study to include 100 subjects. After a clinical decision is made to implement a single drug substitution to ATV +/- RTV, there will be an initial screening visit, at which time the study will be presented to the patient and informed consent for participation will be obtained. A number of evaluations (including blood tests) will be completed to definitively assess a subject's eligibility to participate in this protocol. The patients will continue on their current therapy and will return within the next 14 days for an enrollment visit to review the blood test results and definitively confirm study eligibility. In particular, we will ascertain the continued presence of the side effect/toxicity motivating consideration of a change in therapy. This being down, the quality of life questionnaires (MOS-HIV and ASDM) will be administered for the first time. Once again, the patient will continue on their current HAART and return within the next 14 days for a baseline visit at which time the quality of life questionnaires (MOS-HIV and ASDM) will be administered once again, the results being averaged with those obtained at the time of the enrollment visit, this serving as a more rigorous evaluation of the patient's current status. The patient could be withdrawn from the study if the side effect/toxicity motivating consideration of a change in therapy is no longer present. At this baseline visit, all patients will switch the PI or NNRTI component of their regimen to ATV (+/- RTV). The decision to use boosted or unboosted ATV in this protocol will be left to the discretion of the treating physician. All patients will be receiving ATV (+/- RTV) with food. The dose of the unboosted ATV will be 300 mg (2 capsules, 150mg each) plus RTV (1 capsule, 100 mg). The patients will then be seen in follow up at weeks 4, 12, 24, 32, and 48 after the baseline visit. They will continue on their new therapy (including ATV +/- RTV) for this entire period of observation. Changes in the NRTI backbone will be permitted without constituting a study endpoint, while changes in the ATV +/- RTV that may be required for reasons of efficacy or toxicity will constitute such an endpoint, leading to a patient's withdrawal from the study. At each study visit, the quality of life questionnaires (MOS-HIV and ASDM) will be administered. The results will be compared to the mean results obtained at the enrollment and baseline visits, with each individual participant serving as his/her own control. Measures of adherence to HAART, CD4 cell counts and HIV plasma viral load will also be obtained at each study visit, and will constitute secondary study endpoints.