The Government of the Republic of South Africa is implementing a national program to provide antiretroviral therapy (ART) to all eligible HIV infected South African adults. While the medical effectiveness of ART in suppressing viral replication is well established, little is known about the economic effectiveness of treatment. In particular, it is not known if treatment will offset the impact of HIV/AIDS on labor productivity, household stability, quality of life, and other aspects of social and economic development. The purpose of this study is to estimate the impact of ART on the productivity, economic welfare, and quality of life of adult HIV infected patients in South Africa. The study will investigate:

• the degree of functional impairment among patients seeking care for HIV/AIDS,
• the impact of treatment on the ability of patients to perform normal daily activities and attend work,
• the full economic costs to patients of obtaining treatment,
• the impact of treatment on sources of household income,
• social and economic correlates of adherence to therapy, and
• the cost of delivering ART to different types of patients in diverse settings.

The study will last 4 years and will comprise a one-year cross-sectional analysis and a three-year longitudinal analysis. Data will be collected from questionnaires administered during patients' routine visits to public and non-governmental organization-based HIV clinics in South Africa. In accordance with current South African national treatment guidelines, patients who have started ART will visit a clinic every 3 months during the longitudinal analysis for a total of 12 visits; patients not yet on ART will visit a clinic every 6 months for a total of 6 visits.

Questionnaire responses will be matched to indicators of disease progression and treatment history drawn from patients' medical records. The initial one-year analysis will compare outcomes for groups of patients stratified by disease stage and treatment duration. Longitudinal analysis will compare outcomes before and after the initiation of ART; each participant's responses and medical outcomes will be compared with his or her own previous results and with those of other participants at a similar stage of disease progression or treatment duration. This study will generate information needed to sustain large-scale treatment interventions, improve the focus and management of treatment delivery programs, and provide a better understanding of barriers to treatment adherence among HIV infected South African patients.