ART linked to lower TB risk regardless of initial CD4 count
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
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