3.4 The number of deaths and mortality due to AMR

Burden estimates aim to measure the impact of AMR. Causal interpretation helps to ensure that these burden estimates reflect the real harm caused by AMR. A causal interpretation means the number of deaths due to AMR infections would be defined as the number of deaths that would not have occurred in the counterfactual scenario of the absence of AMR infection within a target population over a specified period of time. In other words: ‘Would this outcome have still happened if AMR wasn’t present?’ Counterfactual scenarios are hypothetical situations used to understand what would have happened if a specific factor or event (like AMR infections) had not been present.

A causal interpretation is useful as it tells you how much harm from AMR infections could be prevented if these infections were avoided. This information is crucial for policy-makers to prioritise resources, for the design and evaluation of infection prevention interventions, and to monitor changes in the burden of AMR.

In the literature, you may encounter terminologies including ‘mortality attributable to AMR’, ‘excess mortality due to AMR’ and ‘population attributable mortality’, which could imply a causal interpretation, but a causal interpretation may not always be achievable. There are differences in definition between these terminologies, which you will revisit in the methodology section. While it is important to familiarise yourself with different terminologies used to describe health impact of AMR infections, the key is to understand the analysis approach used and ask yourself if the analysis meant to reach a causal interpretation. It is a good idea to avoid jumping to the conclusion that an estimate holds a causal interpretation just from the terminology used.