Potential health impacts and costs of active case finding guided by <i>Mycobacterium tuberculosis</i> immunoreactivity survey results in Blantyre, Malawi: A mathematical modeling study

In a study conducted in Blantyre, Malawi, researchers examined the potential health benefits and costs of focused tuberculosis (TB) case finding using data from Mycobacterium tuberculosis (Mtb) immunoreactivity surveys in children. Active case finding (ACF) can help reduce TB transmission, but efficient targeting depends on accurate local surveillance data.

The researchers used mathematical models to compare three approaches to case finding in 33 urban neighborhoods: passive case finding (PCF) alone, PCF combined with untargeted ACF, and PCF with ACF based on ARTI-guided targeted ACF.

The results showed that untargeted ACF could increase life expectancy by 3.3 years (95% credible interval: 1.7 to 5.4) for those with TB disease, but at a high cost. Targeted ACF, covering half of the population, was estimated to identify 80% of all TB cases while achieving a lower cost per disability-adjusted life year (DALY) averted (US$400, 95% credible interval: 20 to 1,000) compared to untargeted ACF (US$700, 95% credible interval: 100 to 1,500).

In the main analysis, these cost-effectiveness ratios were higher than the thresholds available in Malawi, although they improved with assumptions of higher TB prevalence or greater transmission reduction.

The study's conclusions are based on mathematical modeling and are subject to several limitations, including assumptions about the relationship between ARTI and TB prevalence, which remains uncertain. Despite these limitations, the findings suggest that targeting ACF using Mtb immunoreactivity survey data could significantly improve health outcomes and cost-effectiveness compared to untargeted approaches. However, affordable methods for collecting this data are needed to expand the use of this targeted strategy.