HIV positive people in low and middle income countries who take anti-HIV drugs (antiretroviral therapy) are considerably less likely to develop tuberculosis than those who do not take antiretroviral therapy.

The finding, published in this week’s issue of PLoS Medicine is irrespective of the immunodeficiency biomarker CD4 count, which indicates when HIV-positive individuals should initiate antiretroviral therapy.

The World Health Organization currently recommends initiating antiretroviral therapy in adults with CD4 counts below 350 cells/mL although the researchers found that the protective effect also occurred in HIV positive adults with a CD4 count above 350 cells/mL.

Given that the HIV virus destroys the body’s immune system cells that are needed to fight infection, people with HIV are extremely susceptible to developing tuberculosis. In 2010, 1.1 million new cases of tuberculosis were reported in 34 million HIV-positive people. Tuberculosis claimed the lives of 350,000 HIV infected people, making the disease the leading cause of death amongst those diagnosed HIV-positive.

Research leader Amitabh Suthar from the World Health Organization and his team conducted a meta analysis from 11 relevant studies from Sub-Saharan Africa, South America, the Caribbean, and Asia, discovering that the risk of developing tuberculosis in study participants who took antiretroviral therapy was 65% less compared with those not receiving antiretroviral therapy. The findings were independent of the CD4 count at the initiation of antiretroviral therapy.

Significantly, the team discovered that antiretroviral therapy was linked to a 57% lower risk of tuberculosis in adults with CD4 counts greater than 350 cells/mL, which is above the World Health Organization’s current recommendation to start antiretroviral therapy.

The researchers state:

“This review found that antiretroviral therapy is strongly associated with a reduction in tuberculosis incidence in adults with HIV across all CD4 cell counts. Our key finding that antiretroviral therapy has a significant impact on preventing tuberculosis in adults with CD4 counts above 350 cells/ml is consistent with studies from developed countries and will need to be considered by healthcare providers, researchers, policymakers, and people living with HIV when weighing the benefits and risks of initiating antiretroviral therapy above 350 cells/ml.”

They conclude: “Earlier initiation of antiretroviral therapy may be a key component of global and national strategies to control the HIV-associated tuberculosis syndemic.”

Written by Petra Rattue