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Tuberculosis preventive therapy: An underutilised strategy to reduce individual risk of TB and contribute to TB control

Gavin J Churchyard, Richard E Chaisson, Gary Maartens, Haileyesus Getahun

Abstract


Tuberculosis (TB) remains a global health problem, and South Africa (SA) has one of the world’s worst TB epidemics. The World Health Organization (WHO) estimated in 1999 that one-third of the world’s population was latently infected with TB. In SA up to 88% of HIV-uninfected young adults (31 - 35 years) are latently infected with TB. In the most recent meta-analysis, 6 - 12 months of isoniazid preventive therapy (IPT) was associated with a lower incidence of active TB than placebo (relative risk (RR) 0.68; 95% confidence interval (CI) 0.54 - 0.85), with the greatest benefit among individuals with a positive tuberculin skin test (TST) (RR 0.38; 95% CI 0.25 - 0.57). A clinical trial of IPT given with antiretroviral therapy (ART) for 12 months reduced TB incidence by 37% compared with ART alone (hazard ratio (HR) 0.63; 95% CI 0.41 - 0.94). The effect of IPT is limited in high-burden countries. IPT for 36 months v. 6 months reduced TB incidence among HIV-positive, TST-positive participants by 74% (HR 0.26; 95% CI 0.09 - 0.80). A study of more than 24 000 goldminers confirmed that IPT is safe, with only 0.5% experiencing adverse events. A meta-analysis of studies of IPT since 1951 did not show an increased risk of developing resistance. Alternative TB preventive therapy regimens, including high-dose isoniazid and rifapentine given weekly for 3 months, have been shown to have similar efficacy to IPT. Mathematical modelling suggests that scaling up continuous IPT targeted to HIV-positive persons, when used in combination with other treatment and prevention strategies, may substantially improve TB control.


Authors' affiliations

Gavin J Churchyard, Aurum Institute, Johannesburg, South Africa; School of Public Health, University of the Witwatersrand, Johannesburg, South Africa

Richard E Chaisson, Center for Tuberculosis Research, Johns Hopkins University School of Medicine, Baltimore, MD, USA

Gary Maartens, Division of Clinical Pharmacology, Department of Medicine, Faculty of Health Sciences, University of Cape Town, South Africa

Haileyesus Getahun, TB/HIV and Community Engagament, Global TB Programme, World Health Organization, Geneva, Switzerland

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Keywords

Tuberculosis; Isoniazid; Isoniazid prophylaxis

Cite this article

South African Medical Journal 2014;104(5):339-343. DOI:10.7196/SAMJ.8290

Article History

Date submitted: 2014-04-06
Date published: 2014-04-16

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