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

Tuberculosis Treatment

Patients diagnosed with active TB receive an internationally recommended short course anti-TB regimen. This regimen uses a combination of four drugs over a period of 6-8 months (depending on national guidelines) to treat drug-sensitive tuberculosis. The treatment is administered using an approach called directly observed therapy (DOT) to ensure patient adherence.

Unit of interventionPer completed treatment course

FormulationTreatment formulation and dosage dependent on national treatment guidelines

Target populationAdults (15 yrs. and older)

PSI implements a variety of innovative TB and TB/HIV communication and service-delivery interventions to increase TB care seeking and appropriate treatment. This work includes extensive engagement with the private sector to improve the quality of TB care and the integration of TB interventions into PSI’s HIV testing and counseling programs worldwide. For more information, visit our website at:

Model Overview

PSI’s TB DOTS impact model estimates the number of deaths and DALYs averted per completed treatment course of TB DOTS. In the model, PSI’s TB intervention is assumed to have the following impacts:

In order to estimate this impact, a compartment model is used to predict TB incidence, prevalence, and TB-related deaths for a one-year period. There are 10 compartments used to model the progression of TB infection, and there are separate models for HIV-positive and HIV-negative populations because of differences in the transmission properties of TB.

The model runs two scenarios: a baseline scenario, which represents existing TB control parameters (based on the WHO Global Tuberculosis Report 2013), and an intervention scenario, which represents PSI’s TB DOTs intervention. Within both scenarios, the model estimates the potential number of TB cases, deaths, and DALYs (using data from the 2010 Global Burden of Disease study) after one year. In the intervention scenario, however, PSI’s TB DOTS intervention is assumed to reduce treatment delay for TB cases, increase the case detection rate, and improve the treatment success rate. The difference in the total number of deaths and DALYs for each scenario after one year represents the estimated impact of the intervention. It is assumed that the impact of PSI’s intervention is limited to incremental improvements in the delivery of DOTS rather than attributing the total impact of each treated DOTS case to PSI.

Referrals to TB treatment

When a client is referred by PSI to a non-PSI supported service provider, such as the public sector, PSI attributes 50% of the impact of that service to the referral issued by PSI. This impact is only attributed to PSI when the referral is confirmed with appropriate documentation. Referral to treatment is often needed when PSI screens and diagnosis a patient during community outreach or private sector engagement, but cannot provide treatment outside of the public sector. Where PSI is unable to track referred individuals through completion of therapy, we use the documented treatment success rate at the level of the basic management unit to approximate treatment completion among referred patients.

Model Outputs (impact metrics)

Estimates of DALYs averted, deaths averted, CYPs provided, and unintended pregnancies averted represent the projected health impact of the intervention. It is “projected” because it has not been directly measured.

Examples based distribution of DOTS in Myanmar in 2015 Statement of modeled results, examples:

In 2015, an estimated 1,230 deaths and 62,028 DALYs would be averted if 10,000 individuals completed DOTS in Myanmar.