Isoniazid preventive therapy for tuberculosis in South Africa: an assessment of the local evidence base.

Worldwide, South Africa (SA) has the worst tuberculosis (TB) epidemic. In SA, there are > 6.1 million people living with HIV (PLWH) and the country now has the largest antiretroviral treatment programme with > 2 million people receiving combination therapy. While there has been a marked recent decline in HIV-associated deaths, > 50% of TB cases still continue to be diagnosed in PWLH. The current TB control strategy based on passive case finding, chemotherapy of childhood TB contacts and directly observed therapy has clearly failed to control endemic TB in SA. Two recent meta-analyses have shown a > 60% reduction in TB in HIV-infected adults after isoniazid preventive therapy (IPT). SA has implemented the World Health Organization policy and IPT is now recommended for HIV-positive people for up to 36 months. Originally, there was only one SA study included in the evidence base supporting this policy, but subsequently four randomised controlled trials have been conducted in SA populations. These studies, together with local observational studies, are the subject of this local, evidence-based review.