Multicomponent strategy with decentralised molecular testing for tuberculosis in Uganda: a cost and cost-effectiveness analysis

Abstract

Background: Decentralised molecular testing for tuberculosis could reduce missed diagnoses and losses to follow-up in high-burden settings. The aim of this study was to evaluate the cost and cost-effectiveness of the Xpert Performance Evaluation for Linkage to Tuberculosis Care (XPEL-TB) study strategy, a multicomponent strategy including decentralised molecular testing for tuberculosis, in Uganda.

Methods: We conducted a costing and cost-effectiveness analysis nested in a pragmatic cluster-randomised trial of onsite (decentralised) versus hub-and-spoke (centralised) testing for tuberculosis with Xpert MTB/RIF Ultra (Xpert) in 20 community health centres in Uganda. We collected empirical data on the cost of the XPEL-TB strategy (decentralised Xpert testing, workflow redesign, and performance feedback) and routine tuberculosis testing (onsite smear microscopy with specimen transport for centralised Xpert testing) from the health system perspective. Time-and-motion studies were performed to estimate activity-based service costs. Cost-effectiveness was assessed as the incremental cost (2019 US$) per tuberculosis diagnosis and per 14-day treatment initiation.

Findings: The XPEL-TB study ran from Oct 22, 2018, to March 1, 2020. Effectiveness and cost-effectiveness outcomes were assessed from Dec 1, 2018, to Nov 30, 2019 and included 4867 women and 3139 men. On a per-test basis, the cost of decentralised ($20·46, range $17·85-25·72) and centralised ($18·20, range $16·58-24·25) Xpert testing was similar. However, decentralised testing resulted in more patients receiving appropriate Xpert testing, so the per-patient cost of decentralised testing was higher: $20·28 (range $17·68-25·48) versus $9·59 (range $7·62-14·34). The XPEL-TB strategy was estimated to cost $1332 (95% uncertainty range $763-5558) per incremental tuberculosis diagnosis and $687 ($501-1207) per incremental patient initiating tuberculosis treatment within 14 days. Cost-effectiveness was reduced in sites performing fewer than 150-250 tests annually.

Interpretation: The XPEL-TB strategy facilitated higher rates of Xpert testing for tuberculosis at a similar per-test cost and modest incremental cost per tuberculosis diagnosis and treatment initiation. Decentralised Xpert testing, with appropriate implementation supports, should be scaled up to clinics with sufficient testing volume to support a single-module device.

Funding: The National Heart, Lung, and Blood Institute.

Figure 1

Factors influencing the cost-effectiveness of a multicomponent strategy including decentralised molecular testing for tuberculosis in Uganda The figure depicts how the ICER varies from the lowest to highest deciles of each variable across the probabilistic sensitivity analysis simulations. Each dot represents the median ICER value among all simulations with the specified parameter in that decile. For example, the median ICER per 14-day treatment initiation was $614·82 among simulations with equipment costs in the lowest 10% across all simulations. The most influential parameters on cost-effectiveness are those with the largest variation in incremental cost per incremental treatment initiation between the first and tenth deciles. The number of individuals presenting for tuberculosis diagnostic testing, equipment costs, and the percent initiating treatment within 14 days at decentralised sites were the largest drivers of cost-effectiveness. Estimates are based on the per-patient cost of testing. The analysis included all parameters; only the most influential values are shown here. All costs presented in 2019 US$. ICER=incremental cost-effectiveness ratio (incremental cost per additional patient initiated on tuberculosis treatment within 14 days of presenting for care).

Figure 2

Incremental cost-effectiveness of a multicomponent strategy including decentralised testing for tuberculosis over 1 year in simulated districts in Uganda The first two graphs show the incremental cost per incremental 14-day treatment initiation (A) or per incremental tuberculosis diagnosis (B) of decentralised testing for tuberculosis over 1 year in simulated Ugandan districts. Each dot in these panels represents a simulated district with a mean of 5000 symptomatic patients presenting for tuberculosis evaluation annually across health centres of different sizes. Blue dots represent the mean value ($1077 per additional 14-day treatment initiation, $2182 per additional tuberculosis diagnosis), and the blue ellipse represents the 95% confidence region that contains 95% of simulated districts. The second two graphs show the cost-effectiveness acceptability curves for 14-day treatment initiation (C) and tuberculosis diagnosis (D) in the simulated districts. These graphs show the probability of decentralised testing being cost-effective at different willingness-to-pay thresholds, compared with centralised testing. For example, at a willingness to pay of $1000 per additional case initiating treatment within 14 days of presenting for care, the XPEL-TB decentralised testing strategy will be considered cost-effective 9·0% of the time (C). All costs presented in 2019 US$. XPEL-TB=Xpert Performance Evaluation for Linkage to Tuberculosis Care.