Free tool shows cheaper molecular tests could expand TB diagnosis

Worldwide, many people still lack quick, accurate tests for tuberculosis (TB) that meet World Health Organization (WHO) standards. WHO-recommended molecular rapid diagnostics (mWRDs) have improved detection, but rolling them out has been held back by high capital investment, maintenance needs, and the cost of consumables. New, lower-cost near point-of-care (NPOCs) molecular tests have appeared with attractive global-access pricing, promising to expand access to rapid TB diagnosis without overwhelming budgets. To help national TB programs understand the budget trade-offs between established tests and these newer options, Pushpita Samina and colleagues built a flexible cost calculator. The tool was first created in Microsoft Excel for Mac (version 16.91, build 24111020) to collect standardized inputs and organize scenarios. After validating the model, the team converted it into R (version 2025.09.1 + 401) and packaged the interactive app (app.R) with Shiny. The app is now available for free global access, giving TB program staff a practical way to compare costs and plan for adopting NPOCs as part of national testing strategies.

The calculator is organized around a clear input sheet that uses standardized labels so users can enter key parameters in a consistent way. Separate worksheets define diagnostic scenarios and carry out the step-by-step calculations, and a results overview summarizes capital, maintenance, consumable, and other costs. After the Excel model was validated, the calculations and scenario logic were moved into R (version 2025.09.1 + 401) and turned into a Shiny app (app.R) for online use. To illustrate how the tool works, the team ran two hypothetical country case studies comparing current low-complexity automated nucleic acid amplification tests (LCaNAAT)-based strategies with scenarios where near point-of-care (NPOCs) are used as the initial diagnostic. In hypothetical Country A, switching to NPOCs produced cost savings of 43% in Scenario 1 (based on current testing trends) and 38% in Scenario 2 (based on ambitious testing goals). In hypothetical Country B, the corresponding savings were 55% in Scenario 1 and 40.5% in Scenario 2. The analysis found that countries could reach ambitious TB testing targets using NPOCs at roughly the same or lower cost than current LCaNAAT testing.

These findings suggest affordable molecular diagnostics could make a big difference in practice. By lowering capital and maintenance costs, near point-of-care (NPOCs) give TB programs the ability to test and detect more people within the same or slightly larger budgets, which can accelerate progress toward universal rapid TB diagnosis. The online app developed from the validated Excel model allows program managers to test multiple scenarios, see where savings would come from, and plan procurement or rollout strategies with clearer budget estimates. Importantly, the tool preserves the structure of established WHO-recommended molecular rapid diagnostics (mWRDs) while highlighting how newer options can be deployed as initial tests to expand coverage. In short, Pushpita Samina’s calculator offers a practical, evidence-based way to explore whether adopting NPOCs could both save money and boost the number of people reached with rapid TB testing.