Leveraging existing high-throughput HIV platforms for molecular Mycobacterium tuberculosis testing in Busia, Kenya:...

High costs and supply chain disruptions pose real-world challenges to the implementation of decentralized molecular platforms for Mycobacterium tuberculosis (MTB) detection in resource-limited settings. This study evaluated the cost, feasibility, and acceptability of integrating Cobas MTB and MTB-RIF/INH assays (Roche Diagnostics GmBH, Mannheim, Germany) into high-throughput HIV workflows using the Cobas 8800 system in Busia County, Kenya.

Sample and testing volume data were collected from Port Victoria Hospital. Remnant sputum specimens (n = 1208) collected for testing on the decentralized GeneXpert (Cepheid, Sunnydale, CA, USA) platform (standard of care) were analyzed on the centralized Cobas 8800 system. Unit costs were estimated using an ingredients-based approach parameterized within the Testing Platform Cost Model, using real-world throughput data. Operational feasibility and technician acceptability of integrated testing on the Cobas 8800 system were assessed through qualitative surveys and workflow analysis.

The integrated, high-throughput Cobas 8800 system maintained consistent testing volumes (median, 94 samples/day), whereas throughput was sporadic on decentralized GeneXpert platforms (median, four samples/day) because of supply chain disruptions and stockouts. The unit cost of the integrated approach ranged from $16.04 (best-case) to $18.97 (worst-case). The GeneXpert unit cost was $23.53 under expected utilization but $78.63 in the worst-case scenario. Operational feasibility and acceptability were high.

This study was conducted in Busia county, Kenya, potentially limiting generalizability to regions with different health infrastructure or testing volumes. The analysis did not assess clinical impacts (e.g. time to treatment initiation), and assumed the availability of underutilized capacity on existing high-throughput platforms.

Integrating molecular MTB testing into established high-throughput HIV workflows provided superior economic stability versus a decentralized infrastructure, and was feasible and acceptable for laboratory personnel. Strategic scaling of integrated, high-throughput diagnostics to complement near-patient testing may mitigate cost volatility, optimize underutilized testing capacity, and help bridge the national TB diagnostics gap in high-burden, resource-constrained environments.