The integration of tuberculosis and HIV testing on GeneXpert can substantially improve access and same-day diagnosis and benefit tuberculosis programmes: A diagnostic network optimization analysis in Zambia

Abstract

Diagnostic network optimization (DNO), a geospatial optimization technique, can improve access to diagnostics and reduce costs through informing policy-makers’ decisions on diagnostic network changes. In Zambia, viral load (VL) testing and early infant diagnosis (EID) for HIV has been performed at centralized laboratories, whilst the TB-programme utilizes a decentralized network of GeneXpert platforms. Recently, the World Health Organization (WHO) has recommended point-of-care (POC) EID/VL to increase timely diagnosis. This analysis modelled the impact of integrating EID/VL testing for children and pregnant/breastfeeding-women (priority-HIV) with TB on GeneXpert in Zambia. Using OptiDx, we established the baseline diagnostic network using inputs for testing demand (October 2019-September 2020), referrals, testing sites, testing platforms, and costs for HIV/TB testing (transport, test, device) respectively in Zambia. Next, we integrated priority-HIV testing on GeneXpert platforms, historically only utilized by the TB-programme. 228,265 TB tests were conducted on GeneXpert devices and 167,458 (99%) of priority-HIV tests on centralized devices at baseline, of which 10% were tested onsite at the site of sample collection. With integration, the average distance travelled by priority-HIV tests decreased 10-fold (98km to 10km) and the proportion tested onsite increased (10% to 48%). 52% of EID tests are likely to be processed within the same-day from a baseline of zero. There were also benefits to the TB-programme: the average distance travelled/specimen decreased (11km to 7km), alongside potential savings in GeneXpert device-operating costs (30%) through cost-sharing with the HIV-programme. The total cost of the combined testing programmes reduced marginally by 1% through integration/optimization. DNO can be used to strategically leverage existing capacity to achieve the WHO’s recommendation regarding POC VL/EID testing. Through DNO of the Zambian network, we have shown that TB/HIV testing integration can improve the performance of the diagnostic network and increase the proportion of specimens tested closer to the patient whilst not increasing costs.

An Integrated Sample Referral System for HIV Viral Load and Early Infant Diagnosis in North-Western Province, Zambia—A Retrospective Cross-Sectional Study

“…Before the introduction of the referral system, the results showed that both tests (VL and EID) were equally prioritized in terms of reducing the overall TAT, and this also correlated with the DBS sample used for EID and the plasma sample for VL testing. In 2017, the Ministry of Health supported the deployment of point-of-care (POC) EID/VL and the use of diagnostic network optimization (DNO) to improve facility testing and demand creation [ 24 ]. This assisted in reducing the demand for sample couriers in centralized testing.…”

Transforming tuberculosis diagnosis

“…As molecular testing can detect multiple infectious diseases, implementation of molecular testing could enable a diverse range of tests to be carried out in tandem, for example, TB, HIV viral load, SARS-CoV-2, sexually transmitted infections, respiratory syncytial virus, influenza and human papilloma virus, to name a few. Indeed, reports have highlighted the value of integrating TB and HIV testing 10 , and TB and SARS-CoV-2 testing 11 . Comment difficult in young children and people living with HIV.…”

India is well placed to scale innovations in tuberculosis diagnostics

“…Second, India has already purchased nearly 5000 CB-NAAT systems (Xpert MTB/RIF as well as TrueNAT), and thus has a good network available to build on and optimize via Diagnostic Network Optimization (DNO). DNO, a geospatial analytics approach that uses optimization techniques to model a diagnostic network and ensure greatest access to services, while maximizing the overall efficiency of the system, has been successfully used in countries such as Zambia and Lesotho 15 , 16 . However, machines without cartridges are a dead investment.…”