Sputum and tongue swab molecular testing for the in-home diagnosis of tuberculosis in unselected household contacts: a cost and cost-effectiveness analysis

Background: Delayed and missed diagnosis are a persistent barrier to tuberculosis control, partly driven by difficulties collecting sputum and an unmet need for decentralized testing. Household contact investigation with point-of-care testing of non-invasive specimens are hitherto undescribed and may offer a cost-effective solution to strengthen active case finding.

Methods: In-home molecular point-of-care testing was conducted using sputum and tongue specimens collected from household contacts of people with confirmed tuberculosis residing in South Africa. A health economic assessment was executed to estimate and compare the cost and cost-effectiveness of different in-home point-of-care testing strategies, against centralized sputum testing (standard of care) from a provider’s perspective. The primary cost-effectiveness outcome was measured as the incremental cost per additional household contact with TB detected and linked to treatment. Decision analytic modeling was used to estimate and compare incremental cost effectiveness ratios across strategies.

Results: The total implementation cost of delivering the standard of care to 300 households over a 2-year period was $85 188. Strategies integrating in-home point-of-care testing ranged between $88 672 – $97 271. The cost-per-test for in-home point-of-care sputum testing was the highest at $20.08. Two strategies, Point-of-Care Sputum Testing and Point-of-Care Combined Sputum and Individual Tongue Swab Testing were the most cost-effective with ICERs of $641 and $775 respectively, both below a $2 760 willingness-to-pay threshold.

Conclusion: In-home point-of-care molecular TB testing strategies utilizing combination testing of tongue swabs and sputum specimens can meaningfully improve the number of people tested, diagnosed, and notified during household contact investigation, while being cost-effective.