Overcoming challenges in the economic evaluation of interventions to optimise antibiotic use

Abstract

Bacteria are becoming increasingly resistant to antibiotics, reducing our ability to treat infections and threatening to undermine modern health care. Optimising antibiotic use is a key element in tackling the problem. Traditional economic evaluation methods do not capture many of the benefits from improved antibiotic use and the potential impact on resistance. Not capturing these benefits is a major obstacle to optimising antibiotic use, as it fails to incentivise the development and use of interventions to optimise the use of antibiotics and preserve their effectiveness (stewardship interventions). Estimates of the benefits of improving antibiotic use involve considerable uncertainty as they depend on the evolution of resistance and associated health outcomes and costs. Here we discuss how economic evaluation methods might be adapted, in the face of such uncertainties. We propose a threshold-based approach that estimates the minimum resistance-related costs that would need to be averted by an intervention to make it cost-effective. If it is probable that without the intervention costs will exceed the threshold then the intervention should be deemed cost-effective.

Fig. 1. Links between incremental antibiotic use and additional costs of treating resistant infections.

In evaluating the cost-effectiveness of interventions to improve antibiotic use, it is important to find a way to account for the various pathways via which incremental antibiotic use might affect costs due to increased resistance. This figure features a number of pathways via which incremental antibiotic use can increase the cost of treating infections. Economic evaluations of interventions to optimise antibiotic use should account for all these pathways; not only the more easily parameterised pathways in which antibiotic treatment reduces costs by reducing transmission of susceptible bacteria. The arrow to de novo resistance through mutagenesis is dashed, because while this route is likely important for tuberculosis, gonorrhoea and specific bug-drug combinations, other routes might be more important for the majority of infections with resistant bacteria.