Union study in Zimbabwe shows reduction of TB case notifications with scale-up of antiretroviral and isoniazid preventive therapies

An operational research study, published in BMJ Open and led by the Zimbabwe Ministry of Health in collaboration with The Union’s Centre for Operational Research, showed the impact of continued scale-up of antiretroviral therapy (ART) and isoniazid preventive therapy (IPT) on reducing the total number of notified cases of tuberculosis (TB) disease by 66 percent at the national level in Zimbabwe over the study period.

Zimbabwe is one of 14 countries globally with a triple burden of TB, TB-HIV co-infection and multidrug resistant TB. The study findings therefore reaffirm the population impact of the pooled TB-protective effect of ART and IPT in the country, which has a largely HIV-driven TB epidemic. This impact may also be coupled with intensified TB case finding among people living with HIV to identify those eligible for IPT and those needing TB treatment, thus resulting in improved infection control in ART care settings where new diagnoses of people with TB are most prevalent.

Between 2004 and December 2018, TB case notifications declined to 173 people per 100,000 population, down from 510 per 100,000. During this time, ART coverage increased from less than one percent (in 2004) to 88 percent (in December 2018) of people living with HIV in Zimbabwe. IPT coverage among people living with HIV and receiving ART care increased from less than one percent (in 2012) to 33 percent (in December 2018). ART and IPT have a TB protective effect at the individual level among people living with HIV.

The study utilised routinely tracked national aggregate data as global response indicators, providing a comprehensive view of what is prevailing in Zimbabwe over time. Prior to the study, there were no other studies comparing the national scale-up of IPT and ART with national TB case notification rates.

The paper discussed further opportunities for continued impact on TB with increasing coverage of ART and IPT, with a focus on IPT coverage, which currently only reaches approximately one-third of all people on ART. IPT completion rates are still suboptimal, probably because of the difficulty of taking IPT over a period of six to nine-months. The country’s planned national roll-out of a shorter regimen of TB preventive therapy (a 12-week course of weekly rifapentine plus isoniazid (3HP), following pilot studies in early 2020, can potentially lead to increased TB preventive therapy coverage and a further decline in TB incidence among people living with HIV. 3HP has been shown to have higher completion rates and a lower risk of adverse events.

Dr Kuda Takarinda, the lead investigator on this study, said: “the study results support the continued scale-up of ART and TB preventive therapy among people living with HIV as a key strategy for mitigating the dual burden of HIV/AIDS and TB in Zimbabwe and other regions of the world with HIV-driven TB epidemics.”

Dr Takarinda is a senior operational research (OR) fellow with The Union’s Centre for Operational Research and has a leading role in the AIDS and TB Department of Zimbabwe’s Ministry of Health and Child Care. The OR fellowship programme provides training and mentorship to selected public health professionals who want to build a career in OR.

The paper, Trend analysis of tuberculosis case notifications with scale-up of antiretroviral therapy and roll-out of isoniazid preventive therapy in Zimbabwe, 2000–2018, has been published in the April 2020 issue of the BMJ Open.