Is targeted testing for latent tuberculosis infection cost-effective: the experience of Tennessee
MetadataShow full item record
Preventative interventions often demand that resources be consumed in the present in exchange for future benefits. Understanding these trade-offs, in a context of resource constraints, is essential for policy makers. Cost-effectiveness analysis is one tool to inform decision-making. Targeted testing and treatment (TTT) for latent tuberculosis infection (LTBI) consists in identifying people at high risk for LTBI for preventive treatment to decrease the risk that they will develop active tuberculosis disease (ATBD). The state of Tennessee began conducting TTT statewide in 2001. This study uses a decision tree to evaluate the cost and outcomes of TTT for LTBI in Tennessee, compared to passive ATBD case finding (PACF). Key event probabilities were obtained from the Tennessee TTT program and from the literature. Outcomes are measured in terms of Quality Adjusted Life Years (QALY). The cost-effectiveness threshold was set at $100,000/QALY saved. One-way sensitivity analyses around factors related to study design (exclusion of patient costs, secondary transmission, discount rate and analytical horizon), the program’s environment (prevalence of LTBI and drug resistance, ATBD treatment costs) and program performance (program maturity, treatment initiation and completion rate, testing in low-risk group, test characteristics, screening costs) were conducted, as was probabilistic sensitivity analysis (PSA) which takes into account the uncertainty in multiple parameters simultaneously. The base case, with a 25-year time horizon and 3% discount rate, shows that TTT prevents 47 ATBD cases, and saves 31 QALYs per 100,000 patients screened for LTBI at a societal cost of $12,579 (2011 US$) per QALY saved. Sensitivity analyses identified value thresholds that would trigger a change in preferred policy. PSA shows that the likelihood that TTT would be cost-effective is low. Decision makers interested in implementing TTT should carefully assess the characteristics of the local TB epidemic and expected program performance to determine whether TTT is preferable over PACF from a cost-effectiveness viewpoint.