ART linked to lower TB risk regardless of initial CD4 count
This should be considered by healthcare providers, policymakers, and people living with HIV when weighing the benefits and risks of early ART initiation.
Antiretroviral therapy (ART) was strongly associated with a lower incidence of tuberculosis (TB)—regardless of CD4 count when ART began—in an 11-study meta-analysis of TB in HIV-positive adults in developing countries.
HIV infection is the strongest risk factor for TB in countries with high TB prevalence. Of the 34 million people living with HIV in 2010, TB developed in an estimated 1.1 million (3.2%). HIV and TB are coepidemic in many parts of sub-Saharan Africa.
To determine whether ART lowers the risk of TB, researchers planned this systematic review and meta-analysis. They divided CD4 counts when ART began into four groups: (1) less than 200 cells/µL, (2) 200 to 350 cells/µL, (3) more than 350 cells/µL, and (4) any CD4 count.
The investigators searched PubMed, Embase, African Index Medicus, LILACS, and clinical trial registries for randomized trials and prospective and retrospective cohort studies that compared TB incidence (the new diagnosis rate) by ART status in HIV-positive adults for a median of more than 6 months in developing countries. This strategy yielded 11 studies for analysis.
Meta-analysis revealed a strong association between ART and reduced TB incidence in each of the CD4 categories analyzed, at the following hazard ratios [HR] (and 95% confidence intervals):
• Less than 200 cells/µL: HR 0.16 (0.07 to 0.36), 84% lower risk • 200 to 350 cells/µL: HR 0.34 (0.19 to 0.60), 66% lower risk • Greater than 350 cells/µL: HR 0.43 (0.30 to 0.63), 57% lower risk • Any CD4 count: HR 0.35 (0.28 to 0.44), 65% lower risk
The CD4 count at which ART began did not significantly change the size of the preventive impact of ART on TB development.
In analyzing this study, the editors of PLoS Medicine caution that, “because most of the studies in this meta-analysis were observational, these results do not show that ART causes a reduction in tuberculosis incidence—other unknown factors shared by the study participants who received ART may be responsible for their lower tuberculosis incidence.”
The researchers propose that “earlier initiation of antiretroviral therapy may be a key component of global and national strategies to control the HIV-associated tuberculosis syndemic.”
PLoS Medicine editors suggest “the key finding that ART is associated with a significant reduction in tuberculosis cases among adults with CD4 counts greater than 350 cells//μl should be considered by healthcare providers, policymakers, and people living with HIV when weighing the benefits and risks of early ART initiation.”
Source: Amitabh B. Suthar, Stephen D. Lawn, Julia del Amo, Haileyesus Getahun, Christopher Dye, Delphine Sculier, Timothy R. Sterling, Richard E. Chaisson, Brian G. Williams, Anthony D. Harries, Reuben M. Granich. Antiretroviral therapy for prevention of tuberculosis in adults with HIV: a systematic review and meta-analysis. PLoS Medicine. 2012; 9: e1001270.
Complete article provided by PLoS Medicine, an open-access journal
By Mark Mascolini