Project Impact By Country Project Impact By CountryProject Impact By Country
Learn about PSI's models Learn about PSI's modelsLearn about PSI's models

Antiretroviral Therapy

Antiretroviral therapy (ART) is a treatment regimen that uses a combination of antiretroviral drugs to suppress the HIV virus and stop HIV disease among infected patients. ART has transformed HIV infection from being an inevitably terminal disease to a chronic condition that requires ongoing clinical management. Patients require lifelong treatment with ART.

Unit of interventionper patient month

FormulationDepends on country-specific guidelines

Target populationPeople living with HIV

PSI implements a range of HIV prevention initiatives as part of its combination prevention approach. These include the marketing and provision of male and female condoms, HIV testing and counseling, voluntary medical male circumcision, and linkages to care, among others. For more information about these initiatives, visit our website at:

Model Overview

PSI’s ART impact model estimates the number of DALYs averted, deaths averted, and new HIV infections averted per patient month of ART. In PSI’s ART model, an ART intervention is assumed to have the following impacts:

Not all HIV-positive individuals are able to maintain the treatment regimen. For this reason, we incorporate a loss-to-follow-up rate post initiation of treatment throughout the model.

The first step of PSI’s ART model analyzes the increased lifespan of HIV-positive individuals who are on an ART regimen. As HIV-positive individuals live longer, HIV-related DALYs are averted. The model does this by comparing the average life expectancy of an HIV-positive individual on an ART regimen with the average life expectancy of an HIV-positive individual who is not on an ART regimen. This results in an estimate of the average number of years of life saved due to an ART intervention. The Spectrum Suite software is used to model this scenario, in which country profiles are built in Goals and projected in the AIDS Impact Model (AIM).

The model translates the number of new HIV infections averted into the respective estimates of deaths averted and DALYs averted per new HIV infection averted. Finally, the model estimates the number of patient-months required to achieve this reduction in HIV transmission.

Model Outputs (impact metrics) Examples based on distribution of ART in Myanmar in 2015

We are able to produce deaths averted coefficients for maternal deaths and child deaths individually. Within PSI’s Impact Calculator, these estimates are aggregated into a single deaths averted estimate. Estimates of maternal deaths averted are available via the export function within the calculator in most cases. Please contact for more information.

Statement of modeled results, examples:

If 10,000 patient months of ART were distributed in Myanmar in 2015, an estimated 68 new HIV infections, 68 deaths and 4,905 DALYs would be averted