People living with HIV (PLHIV) are at 20–40 times higher risk of developing TB compared to people who do not have HIV. For this reason, TB remains a pressing global health priority particularly in sub-Saharan Africa (SSA) where the HIV epidemic persists.¹ Since 2011, the World Health Organization (WHO) has recommended that TB preventive therapy (TPT) be administered to PLHIV to reduce TB-related morbidity and mortality.² TB preventive therapy has been shown to reduce the incidence of TB disease among PLHIV by 33%–62%.² Isoniazid preventive therapy (IPT) reduces mortality among PLHIV by 37%, independent of antiretroviral therapy (ART).³ The 2011 WHO guidelines conditionally recommend the use of IPT for at least 36 months for PLHIV in high TB- and HIV-prevalence settings. The WHO End TB Strategy aims to get 90% of PLHIV on TPT by 2025. However, uptake of TPT has been poor among PLHIV globally, especially in many countries with high TB and HIV burden.⁴ In 2018, the TPT coverage among PLHIV who newly enrolled in HIV care was 49% globally and 60% in SSA.¹ Various barriers to high TPT coverage have been reported in high TB burden settings, such as lack of awareness and buy-in from healthcare workers, additional burden on clinic staff, commodity stock outs, and distance from health facilities.^5,6

Zimbabwe is one of the 14 countries with high burdens of TB, multidrug resistant TB and HIV.¹ TB incidence among PLHIV in Zimbabwe is 19 estimated at (14–24)/ 1000/annum in 2018¹ and mortality among PLHIV remains 3-fold higher than among those not affected with HIV.³ Given the WHO recommendations for on IPT scale-up among PLHIV, the Ministry of Health and Child Care (MOHCC) piloted implementation of isoniazid (INH) together with pyridoxine in 10 selected sites across five provinces to determine feasibility of scale-up between 2012 and 2013. The pilot showed a high rate of 6 months completion (81%) among 9924 PLHIV who initiated IPT.⁷ In 2014, the Zimbabwe National ART Programme started nationwide scale-up of IPT, prioritizing IPT provision to PLHIV on ART.

With MOHCC-led initiatives to expand IPT coverage, the number of ART clients initiated on IPT increased from 98 in 2012 to 373,819 in 2018.⁸ However, published literature on national IPT uptake in Zimbabwe is scarce. Here, we assessed the prevalence of self-reported IPT uptake among PLHIV and explored factors associated with IPT non-uptake using data from the nationally representative Zimbabwe Population-based HIV Impact Assessment (ZIMPHIA) survey 2015–2016.

In this population-based study of adult PLHIV in Zimbabwe, the self-reported IPT uptake among PLHIV in HIV care was low 2 years post-national scale-up. This is much lower than uptake reported from other Zimbabwe studies with smaller cohorts. Isoniazid preventive therapy uptake among PLHIV was 54% at sixteen health facilities in Midlands Province in 2013 and 52% at four clinics in Bulawayo.^12,13 However, Zimbabwe has achieved rapid progress in expanding IPT coverage in the more recent years. The number of ART clinics offering IPT and new IPT initiations increased exponentially across the country, with decentralization of IPT services to clinics in rural areas. By 2018, 82% of ART clinics offer IPT.⁸ Zimbabwe needs to continue efforts in scaling IPT by addressing the current bottlenecks toward ending TB by 2035. To help design future interventions to improve the IPT uptake in the community, we explored factors associated with IPT non-uptake. Rural/urban residence was the strongest factor associated with IPT uptake, after adjustment for other covariates: IPT uptake was significantly lower in rural areas than in urban areas. Given that by end of 2016, only 611 (35%) of all public health facilities were offering IPT,¹⁴ this is likely a result of IPT being available in district hospitals which are the largest hospital in these settings and tend to offer ART services to larger PLHIV cohorts. It is therefore likely that there are bottlenecks in information dissemination to slower level uptake of services in rural areas in addition to variation in IPT stock availability.

Suboptimal TB symptom screening may be another factor related to the IPT non-uptake. Associations between TB screening at the last HIV care visit and IPT uptake were ubiquitous regardless of residence. Although the survey question was specific to the TB screening at the last clinic visit, this variable may serve as a proxy for on-site TB symptom screening practices in general. In fact, the low proportion of PLHIV screened for TB at their last HIV care visit (48.6%) suggests uneven TB symptom screening practices, although the national guideline recommends all PLHIV are to be screened for TB symptoms at every HIV care visit. Poor IPT coverage related to a failure to screen for TB symptoms has been reported in other African contexts. In a cross-sectional study among PLHIV in Ethiopia, only 68% of symptomatic PLHIV were investigated for TB, which may be attributed by provider barriers such as the absence of IPT guidelines on site, inadequate TB/HIV case management training, and clinicians’ concerns regarding IPT safety (i.e. perceived side effects and increased risk of drug-resistant TB).¹⁵ A qualitative study in Nairobi, Kenya, also emphasized the importance of provider training on IPT, clarity of IPT guidelines, and high-level commitment and support for the IPT program.¹⁶

In this study, we also found different factors have differentiated associations with IPT non-uptake by rural and urban areas. In rural areas, IPT non-uptake was associated with 15–19 year olds. Suggested by consistent reports on poor retention in HIV care among young adult PLHIV,¹⁷ young adults particularly in rural areas might have poor retention in care and be less likely to initiate IPT. On the other hand, in urban areas, IPT non-uptake was significantly associated with hazardous alcohol use. This association was expected because those with a liver disease are not to be given IPT based on adverse effects of hepatotoxicity from IPT use.^18,19 However, it is unclear why the same association was not found in rural areas. This may highlight suboptimal screening practices on IPT eligibility in rural areas. Future interventions should strengthen knowledge and capacity building on IPT scale-up among health workers in rural areas.

Once IPT initiated, reported completion rates are often high, ranging from 69% to 96.8% in high HIV-prevalence and resource-constrained settings.^20–24 In a pilot study in Zimbabwe, 89% of PLHIV who initiated IPT completed a 6-month course.²⁵ Ensuring that all eligible PLHIV receive TPT reduce TB-related morbidity and mortality among PLHIV and help reduce the global TB burden. Maximizing IPT initiation both on provider- and patient-end is critical to enhance public health benefits of IPT.

One of the strengths of this study is use of the nationally representative data from the population-based survey. To our knowledge, this is the first study attempting to assess the prevalence of IPT use across Zimbabwe outside the realm of the pilot program. On the other hand, there are limitations pertaining to self-reported surveys, such as recall bias and social desirability bias. Also, given that the survey was conducted only 2 years after the national scale-up, it is unclear whether participants had a good grasp of understanding on TB preventive treatment, and distinguished it from TB treatment, without any prefatory briefings on TB preventive treatment during the survey. For this reason, the low IPT uptake in this study may need cautious interpretation. However, our figure is similar to the WHO-reported estimate of TPT uptake among PLHIV in 2017 (11%).¹⁴

To our knowledge, this is the first population-based study assessing IPT uptake and exploring factors associated with IPT non-uptake in SSA. The self-reported IPT uptake among PLHIV in Zimbabwe was low 2 years post-national scale-up with challenges observed with IPT uptake in rural areas; among young adult PLHIV and prescribing TB/HIV care practices including TB symptom screening. Six decades since the discovery of TB treatment, the world has learned that treating people with TB alone is not enough to end the global TB epidemic. At the first-ever United Nations High-Level Meeting on TB in September 2018, 120 countries signed a declaration to accelerate the global TB response to eliminate TB by 2030, which includes substantial scale-up of TPT. Future interventions aimed at reducing patient, provider, and health system barriers to ensure delivery of TPT to all eligible PLHIV in the country would help Zimbabwe achieve its targets.