Antiretroviral therapy alone not enough to reduce TB incidence where HIV- and TB- prevalence is high

Incidence of HIV-associated tuberculosis among individuals taking combination antiretroviral therapy: a systematic review and meta-analysis.

Kufa T, Mabuto T, Muchiri E, Charalambous S, Rosillon D, Churchyard G, Harris RC. PLoS One. 2014 Nov 13;9(11):e111209. doi: 10.1371/journal.pone.0111209. eCollection 2014.

Background: Knowledge of tuberculosis incidence and associated factors is required for the development and evaluation of strategies to reduce the burden of HIV-associated tuberculosis.

Methods: Systematic literature review and meta-analysis of tuberculosis incidence rates among HIV-infected individuals taking combination antiretroviral therapy.

Results: From PubMed, EMBASE and Global Index Medicus databases, 42 papers describing 43 cohorts (32 from high/intermediate and 11 from low tuberculosis burden settings) were included in the qualitative review and 33 in the quantitative review. Cohorts from high/intermediate burden settings were smaller in size, had lower median CD4 cell counts at study entry and fewer person-years of follow up. Tuberculosis incidence rates were higher in studies from sub-Saharan Africa and from World Bank low/middle income countries. Tuberculosis incidence rates decreased with increasing CD4 count at study entry and duration on combination antiretroviral therapy. Summary estimates of tuberculosis incidence among individuals on combination antiretroviral therapy were higher for cohorts from high/intermediate burden settings compared to those from the low tuberculosis burden settings (4.17 per 100 person-years [95% Confidence Interval (CI) 3.39-5.14 per 100 person-years] vs. 0.4 per 100 person-years [95% CI 0.23-0.69 per 100 person-years]) with significant heterogeneity observed between the studies.

Conclusions: Tuberculosis incidence rates were high among individuals on combination antiretroviral therapy in high/intermediate burden settings. Interventions to prevent tuberculosis in this population should address geographical, socioeconomic and individual factors such as low CD4 counts and prior history of tuberculosis.

Abstract [1] Full-text [free] access [2]

Editor’s notes: This systematic review and meta-analysis looks at tuberculosis (TB) incidence rates among adults living with HIV on antiretroviral treatment (ART). The review reinforces and quantifies what we already know about the disparities between low-burden and high-burden settings. TB incidence rates in high and intermediate burden settings are ten times higher than those in low burden settings.

The authors draw attention to the need for implementation of programmes that address the social determinants of TB. Low socio-economic conditions are associated with higher TB incidence rates in individuals on ART. Interestingly, the meta-analysis found that TB incidence rates were higher among individuals on ART who had a previous history of TB, than individuals who did not have a history of previous TB. The epidemiological association between previous TB treatment and active TB was one of the foundations for the emphasis on case retention and cure rates with the Directly Observed Treatment, Short-Course (DOTS) strategy. Yet prevalence surveys conducted in Zimbabwe, South Africa and Zambia in the pre-ART and early ART era did not find an association between a history of previous TB and prevalent active undiagnosed TB in individuals living with HIV. The finding from this meta-analysis suggests that individuals on ART are now surviving long enough to develop recurrent TB disease.

The overall message of the study is that ART alone is not sufficient to reduce TB incidence in high HIV prevalence settings. Additional strategies are required to prevent TB focussing on individuals with low CD4 counts, a history of previous TB disease and people who have recently initiated ART.

Avoid TB deaths [4]
Africa [9], Asia [10], Europe [11], Northern America [12]
Brazil [13], Canada [14], China [15], Côte d'Ivoire [16], Denmark [17], Ethiopia [18], France [19], India [20], Senegal [21], South Africa [22], Spain [23], Taiwan [24], Uganda [25], United Kingdom of Great Britain and Northern Ireland [26], United Republic of Tanzania [27], United States of America [28]
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